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DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. NONRESIDENT TRAINING COURSE October 1998 Construction Electrician Intermediate NAVEDTRA 14027
Transcript
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DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

NONRESIDENTTRAININGCOURSE

October 1998

Construction ElectricianIntermediateNAVEDTRA 14027

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DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

Although the words “he,” “him,” and“his” are used sparingly in this course toenhance communication, they are notintended to be gender driven or to affront ordiscriminate against anyone.

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COMMANDING OFFICERNETPDTC

6490 SAUFLEY FIELD RDPENSACOLA, FL 32509-5237

ERRATA 13 Jun 2001

Specific Instructions and Errata forNonresident Training Course

CONSTRUCTION ELECTRICIAN INTERMEDIATE,NAVEDTRA 14027

1. No attempt has been made to issue corrections for errors in typing,punctuation, etc., that do not affect your ability to answer the question orquestions.

2. Make the following changes:

a. Page 5-12, figure 5-10, add the following sentence to the figurecaption: “Lamp is lit when voltage is present.”

b. Page 5-12, figure 5-11, delete the existing figure caption and replacethe caption with “Second step in testing an outlet with a neon tester.Lamp is lit only when voltage is present.”

c. Page 5–13, figure 5-12. Note these changes to the figure: The terminalsin figure 5-12 should be the same as in figure 5-13 (power input on thebottom terminal and load on the top terminal). Consequently, the neontester lead should be on the top terminal and the tester lamp should beOFF to indicate the condition set in the figure caption.

d. Page 5-14, figure 5-17, add the following sentence to the figurecaption. “Lamp should glow only when test lead is in the right sideoutlet slot and voltage is present.”

e. Page 5-15, under the title Fuse, change step 1 to read as follows:“1. First determine if voltage is present at the supply side of the fuseby placing one of the neon tester leads on the top of one fuse and theother lead to ground. Test the other fuse in the same manner. Glowinglamp indicates that voltage is supplied to the fuse.”

f. Page 5-15, under the title Fuse, change step 2 to read as follows:“2. Determine if voltage is present at the load side of the fuse byplacing one lead of the neon tester on the bottom side of the fuse andthe other lead to ground. Test the other fuse in the same manner. If thetester lamp DOES NOT glow and voltage is present at the supply side ofthe fuse, the fuse is defective.”

g. Page 5-16, delete figure 5-19 (all four views).

h. Page 5-22, delete figure 5-28 and delete the first five lines of text inthe left column that apply to figure 5-28.

i. Delete topic on “Airfield Lighting” from page 6-28 through page 6-50.This section on airfield lighting is deleted because airfield lightingis no longer covered by occupational standards for ConstructionElectricians.

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j. Delete chapter 8 on “Alarm Systems.” This chapter is deleted becausefire alarms are no longer covered by occupational standards forConstruction Electricians.

3. Delete the following questions, and leave the corresponding spaces blank onthe answer sheet:

Questions

5-11 through 5-275-64 through 5-75

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i

PREFACE

By enrolling in this self-study course, you have demonstrated a desire to improve yourself and the Navy.

Remember, however, this self-study course is only one part of the total Navy training program. Practical

experience, schools, selected reading, and your desire to succeed are also necessary to successfully round

out a fully meaningful training program.

THE COURSE: This self-study course is organized into subject matter areas, each containing learning

objectives to help you determine what you should learn along with text and illustrations to help you

understand the information. The subject matter reflects day-to-day requirements and experiences of

personnel in the rating or skill area. It also reflects guidance provided by Enlisted Community Managers

(ECMs) and other senior personnel, technical references, instructions, etc., and either the occupational or

naval standards, which are listed in the Manual of Navy Enlisted Manpower Personnel Classificationsand Occupational Standards, NAVPERS 18068.

THE QUESTIONS: The questions that appear in this course are designed to help you understand the

material in the text.

VALUE: In completing this course, you will improve your military and professional knowledge.

Importantly, it can also help you study for the Navy-wide advancement in rate examination. If you are

studying and discover a reference in the text to another publication for further information, look it up.

1998 Edition Prepared byCECS Jose V. P. Ferriols

Published by

NAVAL EDUCATION AND TRAINING

PROFESSIONAL DEVELOPMENT

AND TECHNOLOGY CENTER

NAVSUP Logistics Tracking Number0504-LP-026-7050

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ii

Sailor’s Creed

“I am a United States Sailor.

I will support and defend theConstitution of the United States ofAmerica and I will obey the ordersof those appointed over me.

I represent the fighting spirit of theNavy and those who have gonebefore me to defend freedom anddemocracy around the world.

I proudly serve my country’s Navycombat team with honor, courageand commitment.

I am committed to excellence andthe fair treatment of all.”

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CONTENTS

CHAPTER

1. Construction Support. . . . . . . . . . . . . . . . . . . . . . . .

2. Drawings and Specifications.. . . . . . . . . . . . . . . . . . . .

3. Generators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4. Electrical Distribution. . . . . . . . . . . . . . . . . . . . . . .

5. Interior Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6. Fiber Optics and Lighting Systems.. . . . . . . . . . . . . . . . .

7. Electrical Equipment. . . . . . . . . . . . . . . . . . . . . . . . .

8. Alarm Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . .

APPENDIX

I. References Used to Develop the TRAMAN. . . . . . . . . . . . .

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INDEX-l

PAGE

1-1

2-1

3-1

4-1

5-1

6-1

7-1

8-1

AI-1

Nonresident Training Course Follows The Index

iii

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SUMMARY OF THECONSTRUCTION ELECTRICIAN

TRAINING SERIES

CONSTRUCTION ELECTRICIAN BASIC

Construction Electrician Basic, NAVEDTRA 11038, replaces ConstructionElectrician 3 and should be studied by those seeking advancement to ConstructionElectrician Third Class. The major topics in the Basic TRAMAN are constructionsupport activities, drawings and specifications, power generation and distribution,interior wiring, lighting and communication, and electrical appliances, testequipment, motors, and generators.

CONSTRUCTION ELECTRICIAN INTERMEDIATE

This TRAMAN, replaces Construction Electrician 3&2 and should be studiedby those seeking advancement to Construction Electrician Second Class. Topics inthis book will be a continuation of information covered in the ConstructionElectrician Basic TRAMAN. The major topics in this TRAMAN are constructionsupport, drawings and specifications, generators, electrical distribution, interiorwiring, fiber optics and lighting systems, electrical equipment, and alarm sytems.

CONSTRUCTION ELECTRICIAN ADVANCED

This TRAMAN, when published (refer to NAVEDTRA 12061 for availability),will replace Construction Electrician 1 and should be studied by those seekingadvancement to Construction Electrician First Class. Topics in this book will be acontinuation of information covered in the Construction Electrician IntermediateTRAMAN.

iv

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SAFETY PRECAUTIONS

Safety is a paramount concern for all personnel. Many of the Naval Ship’sTechnical Manuals, manufacturer’s technical manuals, and every PlannedMaintenance System (PMS) maintenance requirement card (MRC) include safetyprecautions. Additionally, OPNAVINST 5100.19 (series), Naval OccupationalSafety and Health (NAVOSH) Program Manual for Forces Afloat, andOPNAVINST 5100.23 (series), NAVOSH Program Manual, provide safety andoccupational health information. The safety precautions are for your protection andto protect equipment.

During equipment operation and preventive or corrective maintenance, theprocedures may call for personal protective equipment (PPE), such as goggles,gloves, safety shoes, hard hats, hearing protection, and respirators. When specified,your use of PPE is mandatory. You must select PPE appropriate for the job since theequipment is manufactured and approved for different levels of protection. If theprocedure does not specify the PPE, and you aren’t sure, ask your safety officer.

Most machinery, spaces, and tools requiring you to wear hearing protection areposted with hazardous noise signs or labels. Eye hazardous areas requiring you towear goggles or safety glasses are also posted. In areas where corrosive chemicalsare mixed or used, an emergency eyewash station must be installed.

All lubricating agents, oil, cleaning material, and chemicals used inmaintenance and repair are hazardous materials. Examples of hazardous materialsare gasoline, coal distillates, and asphalt. Gasoline contains a small amount of leadand other toxic compounds. Ingestion of gasoline can cause lead poisoning. Coaldistillates, such as benzene or naphthalene in benzol, are suspected carcinogens.Avoid all skin contact and do not inhale the vapors and gases from these distillates.Asphalt contains components suspected of causing cancer. Anyone handlingasphalt must be trained to handle it in a safe manner.

Hazardous materials require careful handling, storage, and disposal. PMSdocumentation provides hazard warnings or refers the maintenance man to theHazardous Materials User’s Guide. Material Safety Data Sheets (MSDS) alsoprovide safety precautions for hazardous materials. All commands are required tohave an MSDS for each hazardous material they have in their inventory. You mustbe familiar with the dangers associated with the hazardous materials you use in yourwork. Additional information is available from you command’s HazardousMaterial Coordinator. OPNAVINST 4110.2 (series), Hazardous Material Controland Management, contains detailed information on the hazardous materialprogram.

Recent legislation and updated Navy directives implemented tighter constraintson environmental pollution and hazardous waste disposal. OPNAVINST 5090.1(series), Environmental and Natural Resources Program Manual, provides detailedinformation. Your command must comply with federal, state, and localenvironmental regulations during any type of construction and demolition. Yoursupervisor will provide training on environmental compliance.

Cautions and warnings of potentially hazardous situations or conditions arehighlighted, where needed, in each chapter of this TRAMAN. Remember to besafety conscious at all times.

v

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vi

INSTRUCTIONS FOR TAKING THE COURSE

ASSIGNMENTS

The text pages that you are to study are listed at

the beginning of each assignment. Study these

pages carefully before attempting to answer the

questions. Pay close attention to tables and

illustrations and read the learning objectives.

The learning objectives state what you should be

able to do after studying the material. Answering

the questions correctly helps you accomplish the

objectives.

SELECTING YOUR ANSWERS

Read each question carefully, then select the

BEST answer. You may refer freely to the text.

The answers must be the result of your own

work and decisions. You are prohibited from

referring to or copying the answers of others and

from giving answers to anyone else taking the

course.

SUBMITTING YOUR ASSIGNMENTS

To have your assignments graded, you must be

enrolled in the course with the Nonresident

Training Course Administration Branch at the

Naval Education and Training Professional

Development and Technology Center

(NETPDTC). Following enrollment, there are

two ways of having your assignments graded:

(1) use the Internet to submit your assignments

as you complete them, or (2) send all the

assignments at one time by mail to NETPDTC.

Grading on the Internet: Advantages to

Internet grading are:

• you may submit your answers as soon as

you complete an assignment, and

• you get your results faster; usually by the

next working day (approximately 24 hours).

In addition to receiving grade results for each

assignment, you will receive course completion

confirmation once you have completed all the

assignments. To submit your assignment

answers via the Internet, go to:

http://courses.cnet.navy.mil

Grading by Mail: When you submit answer

sheets by mail, send all of your assignments at

one time. Do NOT submit individual answer

sheets for grading. Mail all of your assignments

in an envelope, which you either provide

yourself or obtain from your nearest Educational

Services Officer (ESO). Submit answer sheets

to:

COMMANDING OFFICER

NETPDTC N331

6490 SAUFLEY FIELD ROAD

PENSACOLA FL 32559-5000

Answer Sheets: All courses include one

“scannable” answer sheet for each assignment.

These answer sheets are preprinted with your

SSN, name, assignment number, and course

number. Explanations for completing the answer

sheets are on the answer sheet.

Do not use answer sheet reproductions: Use

only the original answer sheets that we

provide—reproductions will not work with our

scanning equipment and cannot be processed.

Follow the instructions for marking your

answers on the answer sheet. Be sure that blocks

1, 2, and 3 are filled in correctly. This

information is necessary for your course to be

properly processed and for you to receive credit

for your work.

COMPLETION TIME

Courses must be completed within 12 months

from the date of enrollment. This includes time

required to resubmit failed assignments.

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vii

PASS/FAIL ASSIGNMENT PROCEDURES

If your overall course score is 3.2 or higher, you

will pass the course and will not be required to

resubmit assignments. Once your assignments

have been graded you will receive course

completion confirmation.

If you receive less than a 3.2 on any assignment

and your overall course score is below 3.2, you

will be given the opportunity to resubmit failed

assignments. You may resubmit failedassignments only once. Internet students will

receive notification when they have failed an

assignment--they may then resubmit failed

assignments on the web site. Internet students

may view and print results for failed

assignments from the web site. Students who

submit by mail will receive a failing result letter

and a new answer sheet for resubmission of each

failed assignment.

COMPLETION CONFIRMATION

After successfully completing this course, you

will receive a letter of completion.

ERRATA

Errata are used to correct minor errors or delete

obsolete information in a course. Errata may

also be used to provide instructions to the

student. If a course has an errata, it will be

included as the first page(s) after the front cover.

Errata for all courses can be accessed and

viewed/downloaded at:

http:/ /www.advancement.cnet.navy.mil

STUDENT FEEDBACK QUESTIONS

We value your suggestions, questions, and

criticisms on our courses. If you would like to

communicate with us regarding this course, we

encourage you, if possible, to use e-mail. If you

write or fax, please use a copy of the Student

Comment form that follows this page.

For subject matter questions:

E-mail: [email protected]

Phone: Comm: (850) 452-1001, Ext. 1826

DSN: 922-1001, Ext. 1826

FAX: (850) 452-1370

(Do not fax answer sheets.)

Address: COMMANDING OFFICER

NETPDTC (CODE 314)

6490 SAUFLEY FIELD ROAD

PENSACOLA FL 32509-5237

For enrollment, shipping, grading, orcompletion letter questions

E-mail: [email protected]

Phone: Toll Free: 877-264-8583

Comm: (850) 452-1511/1181/1859

DSN: 922-1511/1181/1859

FAX: (850) 452-1370

(Do not fax answer sheets.)

Address: COMMANDING OFFICER

NETPDTC (CODE N331)

6490 SAUFLEY FIELD ROAD

PENSACOLA FL 32559-5000

NAVAL RESERVE RETIREMENT CREDIT

If you are a member of the Naval Reserve, you

will receive retirement points if you are

authorized to receive them under current

directives governing retirement of Naval

Reserve personnel. For Naval Reserve

retirement, this course is evaluated at 8 points.

(Refer to Administrative Procedures for NavalReservists on Inactive Duty, BUPERSINST

1001.39, for more information about retirement

points.)

COURSE OBJECTIVES

In completing this nonresident training course,

you will demonstrate a knowledge of the subject

matter by correctly answering questions on the

following subjects: Construction Support,

Drawings and Specifications, Generators,

Electrical Distribution, Interior Wiring, Fiber

Optics and Lighting, Electrical Equipment, and

Alarm Systems.

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ix

Student Comments

Course Title: Construction Electrician Intermediate

NAVEDTRA: 14027 Date:

We need some information about you:

Rate/Rank and Name: SSN: Command/Unit

Street Address: City: State/FPO: Zip

Your comments, suggestions, etc.:

Privacy Act Statement: Under authority of Title 5, USC 301, information regarding your military status is

requested in processing your comments and in preparing a reply. This information will not be divulged without

written authorization to anyone other than those within DOD for official use in determining performance.

NETPDTC 1550/41 (Rev 4-00)

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CHAPTER 1

CONSTRUCTION SUPPORT

INTRODUCTION

As a second class petty officer your duties andresponsibilities will increase in the area of con-struction support. This chapter will discuss some ofthese responsibilities, such as the Advanced BaseFunctional Components System, shoring andexcavation safety, project planning, network analysis,timekeeping, quality control, and hazardous materials.

ADVANCED BASE FUNCTIONALCOMPONENTS (ABFC)

The Advanced Base Functional Components(ABFC) System consists of two general-purposepublications: Table of Advanced Base FunctionalComponents with Abridged Initial Outfitting Lists,OPNAV-41P3, and Facilities Planning Guide, Vol-umes I and II, NAVFAC P-437.

The ABFC System was developed to providesupport facilities to constantly changing tactical andstrategic situations. A modular or building-blockconcept was developed. Components were needed thatwould incorporate men, materials, equipment, andfacilities designed and developed to fulfill specificfunctions, no matter where the components wereplaced. The Navy ABFC System is based on the earlyexperience in advanced base planning and shipmentused in World War II with improvements broughtabout by experiences learned in Korea, Vietnam, andthe Persian Gulf.

The Navy ABFC System is the quantitativeexpression and measurement of planning,procurement, assembly, and shipping of material andpersonnel that is needed to satisfy facility supportrequirements. The basic groupings of the ABFCSystem are (1) component, a complete unit; (2)facility, a portion of a complete component; and (3)assembly, a portion of a facility. These simpledefinitions and the interaction of these three units willbe fully explained later in this chapter.

OPNAV 41P3

The Table of Advanced Base FunctionalComponents with Abridged Initial Outfitting Lists

(ABIOL), OPNAV 41P3, is a detailed itemized line-item printout of the material in each ABFC. Eachsystem command (SYSCOM)/bureau is responsiblefor maintaining a detailed list of that portion of theABIOL of an ABFC for which it has been assignedcontributory responsibility.

NAVFAC P-437

The Facilities Planning Guide, NAVFAC P-437,is the basic document that identifies the structures andsupporting utilities of the ABFC System. It consists oftwo volumes.

Volume I contains reproducible engineeringdrawings organized in three parts—Part I, ComponentSite Plans, indexed by component designation; Part II,Facility Drawings and Networks, indexed by facilitynumber; and Part III, Assembly Drawings, indexed byassembly numbers.

Volume II contains the detailed data display foreach component, facility, and assembly in the ABFCSystem. It also has three parts. Part I quantifies anddescribes, by DoD category code, the facilitiesrequirements for each component. Part II quantifiesand describes, by assembly number, the assemblyrequirements for each facility. Part III quantifies line-item requirements, by national stock number (NSN),for each assembly.

Other information used for planning, such as thecrew size, man-hours by skill, land area, and fuelnecessary to make a component, facility, or assemblyoperational is contained in the guide.

The NAVFAC P-437 includes facilities andassemblies that are not directly related to componentsshown in the OPNAV P-41P3. These predesignedfacilities and assemblies give the planner alternativesfor satisfying contingency requirements when thecallout of a complete component is not desired. For thepurpose of compatibility with other DOD planningsystems, the NAVFAC P-437 has been oriented to thestandard DOD category codes for classifying realproperty of the Navy, as listed in Department of theNavy Facility Codes, NAVFAC P-72. The cardinalcategory codes are shown in table 1-1.

1-1

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Table 1-1.—Codes and Categories for Real Property USING THE P-437

CODES CATEGORIES100 Operations and Training200 Maintenance and Production300 Research. Development, and Evaluation400 Supply500 Hospital and Medical600 Administrative700 Housing and Community Support800 Utilities and Ground Improvements900 Real Estate

A facility required for an electrical power plantwill be found in the 800 series, Utilities and GroundImprovements. The assemblies contained within eachof these facilities consist of a grouping of line items atthe national stock number level that, when assembled,will perform a specific function in support of thefacility. These assemblies are functionally grouped insuch a way that the assembly relates to the Seabee skillrequired to install it. These groupings are shown intable 1-2.

When you are using the ABFC System, rememberthat it is possible to tailor it to serve your specificneeds. Understand your exact requirements and mis-sion. Choose components, facilities, or assemblies thatfit or can be tailored to meet your desired goals. Verifystock numbers and descriptions by using appropriatestock lists. Verification is done automatically whencomponents, facilities, or assemblies are ordered.

A sample from volume II of NAVFAC P-437shows the structure and type of information provided.Figure 1-1 shows the P-25 component, Naval MobileConstruction Battalion. The component containsa list-ing of facilities by category code.

One such facility is the electric power plant diesel,2-200 kW without tank, facility, 811 10R. Figure 1-2shows this facility. Note that within the facility thenecessary assemblies are identified.

Figure 1-3 shows an assembly from within facility811 10R. The listing for assembly 32602, titled

"PANELBOARD ASSY 1200A WEATHER-

Table 1-2.—Assemblies Functionally Grouped to Seabee Skills

DESCRIPTIONNUMBER SEQUENCESTART STOP

Builder (BU) OrientedUtilitiesman (UT) OrientedConstruction Electrician (CE) OrientedSteelworker (SW) OrientedEquipment Operator (EO) OrientedWaterfront EquipmentUnderwater Construction and Diving EquipmentOperational SuppliesNBC WarfarePersonnel-Related SuppliesUnassigned at PresentShop Equipment including Maintenance ToolsUnique ABFC Tool KitsNCF TOA Construction Tools and Kits (Power Tools)NCF TOA Construction Tools and Kits (Electric)NCF TOA Construction Tools and Kits (Miscellaneous)NCF TOA Construction Tools and Kits (Rigging)

Shop Equipment (ABFC Unique)

10,000 19,99920,000 29,99930,000 39,99940,000 49,99950,000 54,99955,000 57,99958,000 59,99960,000 62,49965,000 67,49967,500 69,99970,000 79,999

80,000 80,999

81,000 81,99982,000 82,49982,500 82,99983,000 83,99984,000 84,999

85,000 87,499

1-2

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Figure 1-1.—Mobilization component (P-25) for a mobile construction battalion.

PROOF," indicates by line items the national stocknumbers required to make the assembly operable.Assembly listings indicate the installed or collateralequipment provided. Certain installed or collateralequipment supplied by other SYSCOMs or bureaus arenot furnished with the facilities or assemblies listed inthe NAVFAC P-437. They must be ordered separately.

COMPONENT P-25

A breakdown of the component P-25, as shown infigure 1-1, is as follows: a brief header describing themission and capabilities of the component. The siteplan pertaining to each component is depicted by aNAVFAC drawing number. However, drawings involume 1, part 1,are indexed by componentdesignation, not drawing numbers. The word NONEappears for components that have no site plans. The

facilities required to make the component operative arelisted in numerical sequence by DOD category code.The alpha suffix for each facility designator indicatesdifferences between sizes, types, or layouts offacilities for the same functional purposes. Facilitycapacity is expressed in terms of the units of measureused in the NAVFAC P-72. The component capacity isa multiplication of the facility capacity and thequantity. Weight and cube are measured in normalunits for export packing. Weight and constructioneffort are computed using The Seabee Planner’s andEstimator’s Handbook, NAVFAC P-405. Averageconstruction conditions are assumed and computationsare based on normal Seabee skill levels.

You compute the total of the weight, cube, anddollar value columns by adding all facilities orassemblies required in both tropical and northern

1-3

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Figure 1-2.—Typical listing of a facility, facility 811 10R.

Figure 1-3.—Typical listing of an assembly.

climates plus the unique requirements for eithertropical or northern areas.

Summary data located below the componentfacility listings lists the following:

1. Construction standards (const std) are groupedinto two classifications: initial and temporary.

a. INITIAL (INIT)—Duration of requirementless than 6 months.

b. TEMPORARY (TEMP)—Duration ofrequirement from 6 to 60 months.

2. Days of construction duration (lapsed days) arebased on job requirements, optimum constructioncrew size. and full-material availability.

3. Often the land requirements, in acres, basedon the assumed plot plan, will not be followedexactly because of terrain or existing buildings. Theidealized plot plan was developed to design sup-porting utility systems. The material contained inthe utility facilities has been increased to allow forvariation in terrain.

1-4

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4. The connected electrical load in kVA has beencomputed based on knowledge of ABIOL or Table ofAllowance (TOA) contents. A load diversity factorhas been applied to compute the kVA demand. Waterand sewer demand are based on ABIOL or TOAcontents and the utility systems designed to thiscriteria.

5. Compute 30-day requirements for installedengine-driven or fuel-fired equipment only. Noallowance for automotive, construction, weighthandling, and other jobsite support equipment fuel isincluded. Fuel is not provided when facilities orassemblies are shipped. NAVSUP provides fuel as acontribution when whole components are shipped.

6. The skill requirements are designated by Seabee(OF-13) ratings and are expressed in man-hours ascomputed for each facility.

FACILITY 811 10R

Figure 1-2 shows atypical facility entry in part 2 ofvolume I–electric power plant diesel 2-200 kWgenerators, without tank, facility 811 10R. Adjacent tothe facility number, the heading shows the JCSplanning factor applied. The header also describes thebasic capability of the facility. The NAVFAC drawingnumber is shown for reference purposes. All drawingsin volume I, part 2, are indexed by facility number.

The assemblies required to make the facilityfunctionally operational are listed in assembly-numbersequence. These numbers were derived from the primetrade involved in the construction. The 30,000 seriesindicates Construction Electricians; the 50,000,Equipment Operators.

Following a brief description of the assembly isthe zone code. For facilities or assemblies that aredesigned for use in both northern and tropical zones,the zone column is usually left blank. However,assemblies required for Arctic operation aredesignated code “N.” The quantity given is amultiplier, indicating the number of assemblies to beordered.

Weight and cubic feet are measured in normalterms for export packing. Weight, cube, and dollarvalue reflect totals for each line. Constructionestimates are computed in the same manner as arecomponents.

Summarized data is the same as that used forcomponents with the following exceptions. In additionto primary facility capacity, secondary capacity, as

described in NAVFAC P-72, is included. This is used,for example, in the 700 series of facilities where theprimary capacity is expressed in men, and thesecondary, in square feet.

The recoverability code is a broad indication ofthe relocatability or recoverability. The code "A"indicates total recoverability, and "D" indicates adisposable facility. Details are found in table 1-3,Recoverability Codes.

ASSEMBLY 32602

Figure 1-3 shows a typical entry for an assembly.This assembly provides the necessary material for theinstallation of a 200-kilowatt generator. Headerinformation is the same as that for a facility. Assemblyline-item requirements are displayed by cognizancesymbol and national stock number. The unit of issue,weight, cube, and dollar value are extracted fromsupply files once the requirement data is entered. Thisdata changes often, but frequent changes will not bemade in the Facilities Planning Guide for stocknumbers with minor price-level changes.

ORDERING

Components, facilities, or assemblies can beordered. Components are usually ordered only under amobilization situation and requested through the CNO.Facilities and assemblies can be ordered without CNOapproval if reimbursement is provided. Requests forrelease are forwarded to NCBC, Port Hueneme. Atten-tion is directed to the Facilities Projects Manual,OPNAVINST 11010.20 (Series), regarding projectapprovals for peacetime use and to Procurement,Lease, and Use of Relocatable Buildings,OPNAVINST 11010.33 (Series), (DODINST4165.56), regardingthe relocatable building program.

INDEX OF FACILITIES

Suppose there is a requirement for an electricaldistribution system underground. To determine what isavailable in the ABFC System to satisfy therequirement, look in volume 2, part 2, Index ofFacilities, under the 800 series (Utilities and GroundImprovements), as shown in figure 1-4. If anapproximate 11,000-foot system is needed, facility812 30AB can be used; see figure 1-5.

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Table 1-3.—Recoverability Codes

CODE DEFINITION

A. Relocatable: Designed for specific purpose of being readily erected, disassembled, stored, andreused. includes tentage.

B. Pseudo-Relocatable: Not specifically designed to be dismantled and relocated, but could be, withconsiderable effort and loss of parts. Rigid-frame building included.

C. Nonrecoverable: A structure not designed to provide relocatability features or one where the costof recovery of the shelter exceeds 50% of the initial procurement cost. Boltedtanks and steel bridges included.

D. Disposable: Those temporary structures having low acquisition and erection costs which arenot designed for relocation and reuse and may be left on site or destroyed, such asSEAHUNTS.

EXCAVATIONS AND SHORING

Working in, working around. or directing a crew ina trenching or excavation job can be dangerous. Thefollowing paragraphs will give you some of theaccepted engineering requirements and practices.Think safety, not only for your workers but for theother persons that may encounter your work area.

EXCAVATIONS

Preplanning before starting any excavation willsave time and avoid costly mistakes. Give attention topersonal safety equipment, underground utilityinstallations, personnel/vehicular traffic interruptions,security, and public safety. Make sure your crew isaware of the safe working area around a specific pieceof excavating equipment. Set up daily inspections ofexcavations for possible cave-ins or slides. Movingground must be guarded by a shoring system, slopingof the ground, or some other equivalent means.Excavated or other materials must not be stored closerthan 2 feet from the edge.

When crews are working in trenches 4 feet or morein depth, access into or exits out of excavations shouldbe by ramps, ladders. stairways. or hoists. Crew

members should not jump into trenches or use bracingas a stairway.

Banks more than 5 feet high must be shored or laidback to a stable slope, or some other equivalent meansof protection must be provided where crew membersmay be exposed to moving ground or cave-ins. Refer tofigure 1-6 as a guide in sloping of banks.

Sides of trenches in unstable or soft material, 5 feetin depth, are required to be shored, sheeted, braced,sloped, or otherwise supported by sufficient strength toprotect the crew members working within them.

Sides oftrenches in hard or compact soil, includingembankments, must be shored or otherwise supportedwhen the trench is more than 5 feet in depth and 8 feetor more in length.

SHORING

The determination of the angle of repose anddesign of the supporting system must be based oncareful evaluation of many features: depth or cut;possible variation in water content of the materialwhile the excavation is open; anticipated changes inmaterials from exposure to air, sun, water, or freezing;loading imposed by structures, equipment, overlying

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Figure 1-4.—Alphabetical index of facilities.

material, or stored material; and vibration fromequipment, blasting, traffic, or other sources..

PROJECT PLANNING

Materials used for sheeting and sheetpiling,bracing, shoring, and underpinning have to be ingood serviceable condition. Timbers must be soundand free from large or loose knots and must bedesigned and installed to be effective to the bottom ofthe excavation.

Throughout the life of a project, information thatreflects the complete history and requirements for thatproject is being accumulated and updated. The projectpackage is the collection of all information required toplan, schedule, monitor, and execute a project. Duringthe construction phase of a project, inspection reports,field change reports, and numerous items of project

Cross braces or trench jacks must be placed incorrespondence are added to the project package totrue horizontal position, be spaced vertically, and complete the project history file. This file is con-be secured to prevent sliding, falling, or kickouts. tinually updated until the project is completed. TheMinimum requirements for trenching timbers are most critical part of this project package is the projectshown in figure 1-7. planning package.

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Figure 1-5.—Assembly description of facility 812 30 AB, electrical distribution lines underground, 11,000 feet,

Figure 1-6.—Approximate angle of repose.

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Figure 1-7.—Trench shoring-minimum requirements.

PROJECT PLANNING PACKAGE

The entire history of a Naval Construction Force(NCF) project is documented in the standard five-section project package. A list of the contents of theproject package (Seabee Project Package) is shown inTable 1-4. A flowchart showing the sequence ofplanning steps is shown in figure 1-8. It is quite evidentfrom looking at the contents of the project planningpackage and at figure l-8 that planning a project fromthe beginning to the end is an involved process. As asecond class petty officer, you will be expected to

prepare this type of project pack-age, to a certainextent. This manual covers just a few aspects of theproject package folder. For more detailed information,you will need to study the Seabee Crewleader’sHandbook, Operations Officer’s Handbook, andSeabee Planner’s and Estimator’s Handbook,NAVFAC P-405 (Series).

The basic principle of the project package is todivide a project into smaller, controllable units and toset up a project history file. A project is usuallyreceived from the regiment level where it is dividedinto master activities. The next step is to further

Figure 1-8.—Project planning flowchart.

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Table 1-4.—Seabee Project Package

SEABEE PROJECT PACKAGE

(*Required on All Projects)(**Requirement may be waived in a contingency: operation)

SECTION #1 GENERAL INFORMATION AND CORRESPONDENCE

1A *Tasking Letter Correspondence*Outgoing Messages and Correspondence*Incoming Messages and Correspondence

1B Project Scope SheetProject OrganizationProject Planning MilestonesProject Package Sign-off SheetDeployment CalendarPreconstruction Conference SummaryPredeployment Site Visit SummaryJoint Turnover MemorandumPre-BOD Inspection Request

SECTION #2 ACTIVITIES AND NETWORK

2A *Level II Barchart*Two Week Schedules*Master Activity Listing*Master Activity Summary Sheets**Level III Precedence Diagram

2B Level III BarchartConstruction Activity Summary Sheets (Recommended including filled out 1250-1 s.)Construction Activity Summary Sheets on Completed ActivitiesTwo Week Labor SummariesSITREP FeedersOther Computer Printouts/Reports

SECTION #3 RESOURCES

3A *30/60/90-Day Material List*30/60/90-Day Material List Letter

*Bill of Materials*Tool Requirement Summary*Equipment Requirement Summary

3B List of Long Lead ItemsMaterial Take Off WorksheetsBill of Materials/Material Take Off Comparison WorksheetsMaterial Transfer RequestsAdd On/Reorder Justification FormsAdd On/Reorder BMsBorrow Log

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Table 1-4.—Seabee Project Package—Continued

SECTION #4 PLANS

4A *Quality Control Plan Cover Sheet*Quality Control Plan*Safety Plan Cover Sheet*General Safety Plan*Safety Plan*Environmental Plan

4B Daily Quality Control Inspection ReportsField Adjustment Request (FAR) Submittal LogFARsRequest For Information (RFI) Submittal LogRFIsDesign Change Directive (DCD)Concrete Placement Clearance FormsPre-placement Photos for Concrete PlacementsAsphalt Pavement Clearance FormsUtility Interruption RequestExcavation RequestRoad Closure RequestEngineering Service RequestMinerals Products RequestOther QC FormsDaily Safety Inspection ReportsEmergency Phone NumbersNavy Employee Report of Unsafe or Unhealthful Working ConditionsRequired Safety EquipmentDaily Safety Lecture LogAccident/Near Mishap/Mishap ReportsHighlighted 29 CFR 1926Hazardous Materials Inventory SheetOther Safety Forms

SECTION #5 DRAWINGS/SPECIFICATIONS

5A *Project Plans**Highlighted Specifications

5B Site LayoutShop DrawingsDetailed Slab Layout DrawingsForming PlansRebar Bending ScheduleOther Sketches/DrawingsTechnical Data

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Table 1-5.—Information for a Precedence Activity(Typical Activity Block)

ACTIVITY ACTIVITY

NUMBER DURATION(DUR)

ACTIVITYEARLY DESCRIPTION EARLYSTART

(ES)ACTIVITY

FINISH

RESOURCES (EF)

LATE TOTAL FREE LATESTART FLOAT FLOAT FINISH

(LS) (TF) (FF) (LF)

break down the project into construction activities.This is normally done at the battalion level. From theconstruction activities, you will develop a logicnetwork that will link the activities together into a

sequence of events from the beginning to the end andwill show the dependencies between the activities.Table 1-5 shows an activity block that represents asingle construction activity.. This is the building blockon which the whole project will be planned andcontrolled. The connection of these blocks and theirinterdependence on each other makes up a networkdiagram. The sum of these network diagrams is calleda network analysis.

NETWORK ANALYSIS

A network analysis is a method of planning andcontrolling projects by recording their inter-dependence in diagram form. This enables each funda-mental problem involved to be undertaken separately.The network diagram form is drawn in such a way thateach job is represented by an activity on the diagram,as shown in figure 1-9. This network diagram is basedon the installation of the generators shown infigure 1-10.

Figure 1-9.—Network diagram for installation of two 200-kilowatt generators.

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Figure 1-10.—Layout drawing for a 400-kilowatt electrical power plant.

Advantages

Network analysis has many advantages. As amanagement tool, it readily separates planning fromscheduling of time. The diagram, a picturerepresentation of the project, enables you to see theinterdependencies between events and the overallproject to prevent unrealistic or superficial planning.Resource and time restraints are easily adjustable topermit changes in the plan before its evaluation.

Because the system splits the project into indi-vidual events, estimates and lead times are more accur-ate. Deviations from the schedule are quickly noticed.Manpower, material, and equipment resources can beeasily identified. Since the network remains constantthroughout its duration, it is also a statement of logicand policy. Modifications of the policy are allowed,and the impact on events is assessed quickly.

Identification of the critical path is useful if thecompletion date has to be advanced. Attention can thenbe concentrated toward speeding up those relativelyfew critical events. The network allows you toaccurately analyze critical events and provide the basisfor the preparation of charts. This results in bettercontrol of the entire project.

Disadvantages

The only disadvantage of network analysis as aplanning tool is that. when attempted manually, it is a

tedious and an exacting task. Depending upon justwhat the project manager wants as output, the numberof activities that can be handled without a computervaries, but the number is never high. If calculations arein terms of the sequence of activities only, a projectinvolving several hundred activities may be attemptedmanually. However, the chance for error is high. Thetime required for manual operation would becomecostly. Various alternative plans also may beimpossible because of the large volume of work.

On the other hand, a standard computer programfor network analysis, CBCM 2.1, can handle projectplans and management and give the user the flexibilityto select different alternatives from a list of availablemenus.

The project manager, NOT the computer, is stillresponsible for planning and must make decisionsbased on information supplied by the computer. Com-puter output is only as accurate as its input, which issupplied by people.

TIMEKEEPING

Timekeeping and labor reporting are of greatimportance to the operation of Seabee units. Whilethese are functions of both NCF units and public worksactivities, the discussion in this chapter is limited toNCF units. As a Seabee crew leader, you may beinvolved in the preparation of daily time cards.Therefore, you should know the types of information

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called for on time cards and understand the importanceof accuracy in labor reporting. Although the formsused for this purpose may vary slightly between NCFunits, the discussion in this chapter will suffice asbeing typical.

LABOR ACCOUNTING SYSTEM

To record and measure the number of man-hoursspent on various functions, a labor accounting systemis mandatory. This system must permit the day-by-dayaccumulation of labor utilization data in sufficientdetail and in a manner that allows ready compilation ofinformation required by the operations department inthe management of the manpower resources and in thepreparation of various reports.

REPORTING

All labor expended in carrying out assigned tasksand functions must be accounted for. This accountingmust include the work performed by the reporting unitand, when applicable, work performed by civilianlabor and by military personnel of other activities.Labor expenditures must be accumulated under anumber of reporting categories. This degree ofreporting detail is required to provide the managementdata necessary to determine labor expenditures onproject work. This data is necessary for calculation ofstatistical labor costs and comparison of actualconstruction performance with estimating standards. Italso serves to determine the effectiveness of laborutilization in performing administrative and supportfunctions, both for internal unit management and fordevelopment of planning standards by others.

Job Order Number

Each project that is assigned to the NCF forcompletion has a job order number (JON) assigned.This identification number is required for laboraccounting and reporting purposes.

Time Cards

Time cards are the most accurate way to recordactual man-days on a construction project. Cards allowyou to monitor the efficiency and accountability ofyour crew. Cards are the basis of your report input;therefore, it is imperative that time cards are filled outcorrectly and accurately.

CREW SUPERVISOR’S REPORT

The standard form used for timekeeping is thePrime Time Card shown in figure 1-11. The time cardis prepared by the crew leader for each phase of theconstruction project. The time card provides a break-down by man-hours of the activities in the variouslabor codes for each crew member for any day onany project. Sub-contractor crew leaders will usethe Sub Time Card shown in figure 1-12. Refer toCOMSECONDNCB/COMTHIRDNCBINST 5312.1 formore detailed information on timekeeping and fillingout time cards.

QUALITY CONTROL

The purpose of quality control is to preventdiscrepancies and ensure the quality of workmanship

Figure 1-11.—-Prime Time Card.

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Figure 1-12.—Sub Time Card.

and materials meets the requirements in the plans andspecifications. The responsibility for qualityconstruction rests with the crew leader and the chain ofcommand. The quality control division of theoperations department is responsible for conductingtests and inspections to ensure compliance with theplans and specifications.

QUALITY CONTROL PLAN

The crew leader must develop and implement anaggressive quality control (QC) plan. The crew leadermust plan quality into the project and avoiddiscrepancies. The development of the QC plan can bebroken down into the following steps:

Establish quality measures by reviewing theplans and specifications and identifying the qualitycriteria with which you must comply. The project QCplan should include a list of checks, inspections, andtests. You also need to address special requirements,such as training, hazardous material, or personnel safetypro-tection. See figures 1-13 and 1-14 for examples ofQC planning guides.

Select construction methods that are safe andof high quality. You need to determine constructionmethods very early in the planning stage of the project,as they impact on equipment, tools, material, labor,training, and safety requirements. Discuss construc-tion methods with your crew, supervisors, and the QCinspector.

Identify required training and equipment Ifspecialized training or qualifications are needed, you

must make sure they are met. Use the resources that areavailable to you, and remember that projects areintended as training for your people. Teaching yourcrew the proper construction methods and techniquesshould be high on your priority list.

Ensure personnel awareness. To perform thework satisfactorily, the crew must understand thequality measures. Before beginning work on an activity,you should brief all crew members about criticalmeasurements, inspection items, potential problems,and each member’s responsibility for quality.

Evaluation of work completed is recorded on aDaily QC Inspector’s Report shown in figure 1-15. Thepurpose of this report is to document that the requiredchecks, tests, and inspections were accomplished, andwork is being performed according to specifications.

RESIDENT OFFICER IN CHARGE OFCONSTRUCTION (ROICC)

The ROICC is responsible for inspection andsurveillance on NCF projects and for reviewing dailyQC reports. The ROICC office also has to approve anyrecommended field changes or customer-requestedchanges. No field changes can be made without arequest being forwarded through the QC department.

HAZARDOUS MATERIAL

As a second class petty officer and crew leader,you should be aware of the Navy’s Hazardous Material(HM) and Hazardous Waste (HW) programs.

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PROJECT QC PLAN

I. Project Number and Title:

II. Project Location:

III. Prime Contractor:

Subcontractor: (a)(b)

IV. Project Scope:

V. Types of Testing Required (soil. concrete, etc. ):

VI. Types of Associated Risk (fire, fumes, noise, etc.):

VII Special Training Requirements:

VIII. Special License Required:

IX. Engineering Controls (guard rails, welding curtains, etc.):

X. Testing Equipment Required (state how it is to be used):

Xl. Personal Protective Equipment Required for Testing:

Project Planner.Print name, rate, and company/det

QC Chief: Approved/DisapprovedSignature

Reason for disapproval:

CEIF0113

Figure 1-13.—Project QC plan.

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QUALITY CONTROL PLAN

Figure 1-14.—Quality control plan.

Figure 1-15.—Daily Quality Control Inspector’s Report.

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Naval Construction Force Occupational Safetyand Health Program Manual, COMSECONDNCB/COMTHIRDNCBINST 5100.1, incorporates manynaval instructions into a single document to establishpolicy, assign responsibility, promulgate, andimplement the Naval Construction ForceOccupational Safety and Health Program. Chapter 9of this instruction deals with the Hazardous MaterialControl Program (HMCP). This Navy-wide programcovers the proper storage, handling. usage. anddisposal of HM. Hazardous material. as used in thisinstruction, follows the definition given for hazardouschemicals in 29 CFR 1910.1200 and Federal Standard313B. Every command in the Navy will have anHMCP in place and each command will have thefollowing responsibilities:

Issue local instructions that incorporate therequirements of COMSECONDNCBICOMTHIRD-NCBINST 5100.1 and 29 CRF 1910.1200 into a writ-ten hazardous communication program.

Develop and update, on an annual basis, acomplete inventory of all HMs used at the command.Include in the inventory the location, quantity, stocknumber, chemical or common name. shelf life whereappropriate, and disposal requirements for each HM.

Develop and implement an HM information andtraining program.

Have available for review an Material SafetyData Sheet (MSDS) as required in 29 CFR 1910.1200for each HM used or stored.

For HM purchased locally, obtain an MSDS, orequivalent data sheet. at the time of purchase.

Maintain a complete file of MSDS on the matrialsused, and make the MSDS or a worker-orientedsummary of the MSDS information available to the usersof the HM.

Use the Type of Storage Codes listed in OPNAV-INST 5090.1 to determine safe storage. handling, and use.

Report HM mishaps according to OPNAVINST5102.1, chapters 3 and 4, as appropriate.

Comply with all requirements for disposal of HMrequired by OPNAVINST 5090.1; Title 40, Code ofFederal Regulations, Parts 122 and 260-267; and stateand local regulations.

Indicate the presence of any HM on all shoreequipment, tanks, pipes, or other stationary objects.

The established uniform policy, guidance, andrequirements for the life-cycle control and manage-ment of HM are Navy policy, and you play an importantrole in its success. The safety of personnel is a vitalconcern and is the responsibility of all supervisors.Safety and health considerations for individuals are afundamental element in the operation of allconstruction, facilities, equipment, and training. Tightschedules and adverse working conditions must not beaccepted as excuses for relaxation of safety standards.”

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CHAPTER 2

DRAWINGS AND SPECIFICATIONS

INTRODUCTION

Working with drawings and specifications (specs)is an essential part in your development as aConstruction Electrician. You must be able tointerpret, plan, estimate, and schedule constructionprojects, using the information supplied by thedrawings and specifications. You will need to picturethe separate operations mentally as the workprogresses through the various stages of construction.You must use good judgment when determining whateffect numerous factors and conditions have on aproject and what allowances should be made for eachof them. You must have ready access to informationabout the material, the equipment, and the laborrequired to perform various types of work underconditions encountered as part of the NavalConstruction Force (NCF). In this chapter, we discussthis important phase of your work, that is, workingwith drawings and specifications.

Project concepts are developed by local activities.Their supporting documentation for a constructionproject is forwarded to NAVFACENGCOM,Engineering Field Division (EFD), for requirementvalidation, technical adequacy of the design solution,and reasonable cost estimate. Once a project has beendesigned, approved, and funded, it then must beaccepted by COMSECOND/COMTHIRDNCB fortasking to the Seabee community. Your firstencounter with a project that may have taken yearsto develop and fund will be the drawings andspecifications.

From the beginning (a facility deficiency) to theend (a deficiency corrected), an involved process takesplace. As a member of the NCF, you are the person whomakes the needs and ideas of the naval communitycome to reality.

DEFINITIONS

To be able to work with, and from, drawings andspecifications, you must know the terms commonlyassociated with planning, estimating, and scheduling.We have defined a few of the terms you will need to doyour job. Read them with care, but do not try to

memorize them. Remember where you found them soyou can refer to these terms whenever you have to usethem.

Activity estimates consist of a listing of all thesteps required to construct a given project. Activityquantities provide the basis for preparing the material,equipment, and manpower estimates. They are used toprovide the basis for scheduling, material deliveries,equipment, and manpower.

Bill of material (BM) is a tabulated statement ofthe material required for a given project. It containssuch information as stock numbers, unit of issue,quantity, line-item number, description, vendor, andcost. Sometimes the bill of material will be submittedon either material estimate sheets or material takeoffsheets; the two sheets contain similar information.Usually, the takeoff sheet is an actual tally andcheckoff of the items shown, noted, or specified on theconstruction drawings and specifications.

Construction activities are a breakdown ofmaster activities. They identify functional parts of theproject and are often assigned to a particular company(Bravo/Charlie) or rating.

Detailed estimates are precise statements ofquantities of material, equipment, and manpowerrequired to construct a given project. Underestimatingquantities can cause serious delays in construction orcan result in unfinished projects. A detailed estimatemust be accurate to the smallest detail to quantifyrequirements correctly.

Direct labor includes all the labor expendeddirectly on assigned construction tasks, either in thefield or in the shop, that contribute directly to thecompletion of the end product.

Equipment estimates consist of a listing of thevarious types of equipment, the amount of time, andthe number of pieces required to construct a givenproject.

Estimating is the process of determining theamount and type of work to be performed and thequantities of material, equipment, and labor required.

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Indirect labor includes labor required to supportconstruction operations but does not. in itself. producean end product.

Manpower estimates consist of a listing of thenumber of direct labor man-days required to completethe various activities of a specific project. Theseestimates may show only the man-days for eachactivity or they may be in sufficient detail to list thenumber of man-days for each rating.

Master activities consist of a breakdown of acomplete project in sufficient detail to provide acomprehensive description of the project.

Material estimates consist of a listing anddescription of the various materials and the quantitiesrequired to construct a given project. Information forpreparing material estimates is obtained from theactivity estimates. drawings, and specifications.

Planning is the process of determining require-ments and devising and developing methods and ascheme of action for construction of a project. Goodconstruction planning is a combination of variouselements: the activity, material, equipment, andmanpower estimates: project layout; project location;material delivery and storage; work schedules; qualitycontrol; special tools required; environmentalprotection: safety; and progress control. All of theseelements depend upon each other. They must be takeninto account in any well-planned project.

Preliminary estimates are made from limitedinformation. such as the general description of projectsor preliminary, plans and specifications having little orno detail. Preliminary estimates are prepared toestablish costs for the budget and to program generalmanpower requirements.

Scheduling is the process of determining when anaction must be taken and when materials, equipment,and manpower will be required. It shows the sequence,the time for starting, the time required for perfor-mance. and the time for completion.

SPECIFICATIONS

Specificationsare written information about how abuilding or project is to be built. They are preparedunder the direction of the architect and engineer. Thetype and quality, of materials, workmanship, finish.and final appearance are spelled out. The writtenspecifications, along with the drawings. should give allthe information needed to complete any project.Specifications control the actions and performance of

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all parties who are working on or supplying material toa construction project. Specifications may be only afew pages long and give general instructions andspecific information on materials. Short specificationsare common in small construction jobs. In heavyconstruction. however. specifications may runhundreds of pages. Unless you understand how thevarious parts of he specifications interrelate. the sheermass of the written material can be confusing.Specifications are composed of three major parts:

Bid and contract forms

General conditions

Technical specifications

As an electrician, you will be working withspecifications that deal with the technical areas relatedto your job. You will be responsible for the general andsupplemental specifications. special conditions. andaddenda or changes to conditions that may affect you.

The technical specifications spell out exactly whatmaterial is to be used. what standards are to be met. andwhat work is to be done in all areas ofconstruction. TheConstruction Specification Institute (CSI) hasdeveloped a standard format that is widely followed todevelop complete specifications. Bidding and contractrequirements are covered in Division 0. Technicalspecifications are covered in Divisions 1 through 16.Division 17, expeditionary structures, was establishedspecifically by, NAVFAC. As you can see from table2-1, the specifications are arranged in the sequence inwhich the project will progress. starting with biddingand contract requirements.

CONSTRUCTION DRAWINGS

The main basis for defining the required activities,measuring the quantities of material, and makingaccurate estimates is the information contained in con-struction drawings. You should read all notes andreferences carefully and examine all details and refer-ence drawings thoroughly. You should check the ori-entation of sectional views carefully. Verify theRevision section near the title block to check whetherthe indicated changes were in fact made in the drawingitself. When inconsistencies are found between draw-ings and specifications. the specifications should takeprecedence.

Drawings are generally categorized according totheir intended purposes: preliminary drawings. pre-sentation drawings. working drawings. and shopdrawings.

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Table 2-1.—Technical Specifications

DIVISION # AREA OF CONSTRUCTION

Division 0 Bidding and Contract Requirements

Division 1 General Requirements

Division 2 Site Work

Division 3 Concrete

Division 4 Masonry

Division 5 Metals (Architectural and Structural)

Division 6 Wood and Plastics

Division 7 Thermal and Moisture Protection

Division 8 Doors and Windows

Division 9 Finishes

Division 10 Specialties

Division 11 Equipment

Division 12 Furnishings

Division 13 Special Construction

Division 14 Conveying Systems

Division 15 Mechanical

Division 16 Electrical

Division 17 Expeditionary Structures

A building project may be broadly divided intotwo major phases: the design phase and theconstruction phase. First, the preliminary drawingsare prepared during the design phase. They areprepared by the EFD or by an architect’s andengineer’s (A/E) firm. The preliminary drawings areused for exploring design concepts between thedesigner and the user (customer), making materialselection, getting preliminary cost estimates, andserving as a basis for preparing the finished workingdrawings.

The presentation drawings are developed toshow the proposed building or facility in an attractivesetting in its natural surroundings at the proposed site.Since these drawings are actually used to sell an idea or

a design, you will probably see this type of drawingonly as a cover sheet to a set of construction drawings.

In the second phase, after approval has been givenfor construction, the working drawings aredeveloped. Shop drawings are supplied bymanufacturers to show fabrication of building parts.After review by the architect and engineer, theybecome a part of the working drawings. Throughoutyour career, you will hear working drawings referredto as blueprints, construction drawings, prints, orplans. Basically, these terms are all correct; they can beused interchangeably.

As mentioned earlier, the construction drawingsare developed from the preliminary drawings. With thecollaboration of the EFD and the architect and theengineer, both the materials to be used and the

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construction methods to be followed are decided. Theengineer determines the loads that the supportingstructural members will be required to bear anddesigns the mechanical systems. such as heating.power. lighting, and plumbing.

As a crew member or a supervisor. you will findthe construction drawings. the specifications. and thebill of material your main sources of informationduring the construction and estimating phases of theproject.

Drawings are commonly indexed so you can easilyfind the sheet you need. The drawing index is locatedon the cover sheet or sheet 1 of the set. They are dividedinto eight categories and appear in the following order:

1. Plot and vicinity

2. Landscape and irrigation

3. Architect

4. Structural

5. Mechanical

6. Plumbing

7. Electrical

8. Fire protection

WORKING SKETCHES

A working sketch is a drawing made from theworking drawings to express a tasking clearly and toprovide a quick reference to job requirements. It isdrawn to help show actual conditions on the job, whatsize pipe is to be installed, or where connections will bemade. The sketch should show as much detail aspossible to help your crew during installation ortroubleshooting. A working sketch will usually showthe work you want your crew to accomplish in aselected area and will provide ready reference tojobsite conditions.

A crew should have a working sketch with themwhile working. It will show them how, what, where,and when things happen in the sequence of the job.Your first step in making a working sketch should be todraw the symbols that represent all the fixtures orequipment that is to be installed and locate them withinthe room. Try to draw them in the sequence ofinstallation and include measurements. The amount ofdetail you use in a working sketch will be determinedby the crew’s experience, the complexity of thesystems involved, and the need for cooperation withother trades working on the jobsite.

AS-BUILT DRAWINGS

Upon the completion of a facility, the crew leaderor project supervisor should provide marked prints thatindicate any construction deviations. The informationrequired must show all features of the project asactually, built. As-built drawings should be reviewedafter they are completed. This review assures that allinformation appearing on the drawings shows theexact as-built conditions.

From the as-built drawings, record drawings areprepared. These drawings are the original constructiondrawings, but they are corrected according to the as-built marked print. They then provide a permanentrecord of as-built conditions. The final recorddrawings must be kept up to date at all times. If thismaintenance requires a change to the record drawing,then this information should be passed on and therecord drawings updated.

BLUEPRINT LANGUAGE

To understand the instructions and dimensions ona working drawing, you must be able to read andunderstand the language of the prints not only for yourparticular job but also for all the different phases.Plans, specifications, and details go together. It isimpossible to use one successfully without the other.Never overlook a reference note on a drawing. Theblueprints contain the information and directions thatrequire you to do your part of the total job as planned. Itis also important to follow all the instructions on ablueprint faithfully. Any deviation on your part maymake it impossible for fellow tradesmen to do theirwork properly or successfully.

To read blueprints, you must understand themeanings of all devices, such as various lines,symbols, conventions, abbreviations, and methods ofgiving dimensions and working directions.

TYPES AND WEIGHTS OF LINESFOUND ON DRAWINGS

The types of lines the electrician should be able toread and understand are given below. In figure 2-1these lines are shown as they may appear on a drawing.

Trim line: a light, continuous line along which thetracing is trimmed to square the sheet.

Border line: a heavy, continuous line that outlinesor borders the drawing. The drawing is completewithin this lined border.

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Figure 2-1.—Construction drawing lines.

Main object line: a heavy, unbroken line used toshow visible outlines or edges that would be seen bypeople looking at the article, house, or building. Themain object line is one of the most important linesbecause it outlines the main wall lines on plans andsections. It shows clearly the important parts of theconstruction and emphasizes the outline of theelevations.

Dimension line: a light line drawing outside thestructure or detail to show the distance between twopoints. This line is drawn between extension lines withan arrowhead on each end. Between the arrowheads,the distance will be given either at a break in the line orjust above the line. On some drawings the scale and thedistance between the two points may not agree; in suchcases, the distance will be given in a dimension line.

Extension line: a line that touches and is used withdimension lines. This line extends out from the edge orthe point at which the dimension is to be determined.

Equipment line: a light, continuous, unbrokenline used to show the location of equipment, such astransformers, panels. and galley equipment. This lineis used to allow the electrician to install the necessaryconduit in the proper location during rough-in work.

Symbol section line: lines that are generally solid,although, for certain conventions, dotted lines of thesame weight may be used. Section lines, evenlyspaced, are used to shade surfaces shown on a drawingand by these means indicate the material used. Materialsection lines are standardized to a certain degree, butyou will find some variations. A set of workingdrawings using these symbols would have a symbolschedule key showing the various materials in that

particular set. This schedule is usually placed near thetitle box on the plan of the first floor.

Broken line: a line with wavy breaks in it, atintervals, used to indicate those parts that have beenleft out or that the full length of some part has not beendrawn. The broken line is used in detail drawingswhere only a section of the object is to be shown.

Invisible line: a line that is made up of a series ofshort dashes. It is used to indicate a hidden or aninvisible edge or edges that are hidden under someother part of the structure.

Center line: a line that is made up of alternatinglong and short dashes and is used to indicate the centerof an object.

Section line: a solid line that has arrowheads ateach end that point in the direction in which the sectionis to be taken. This line tells just where the section linehas been cut through the wall or building. The sectionsare indicated, in most cases, by the letters A-A, B-B,and so forth, although numbers are sometimes used.Do not overlook these section lines on a plan. To obtaina clear picture of the construction at the particular pointindicated, always refer to the section detail called forby the letter or number.

Stair indicator line: a solid line with anarrowhead indicating the direction of the run. Forexample, Up 12-R means that there are 12 risers fromfloor to floor and that the stairs go up. A riser is thevertical part of the step; the flat part on which one stepsis the tread. In most cases, the floor plan indicates onlythe run of stairs half the distance between floors. Forexample, the ground floor indicates a broken line thattells you the steps continue up. The next floor planshows the stair indicator line half the distance to thefirst floor, down.

Break line: a thin solid ruled line with freehandzigzags used to reduce the size of a drawing required todelineate an object and reduce detail.

ABBREVIATIONS AND SYMBOLS

Blueprints show a small-scale drawing of a full-size building. Since the blueprints are small in relationto the actual building,some kind of shorthand isneeded to give the necessary building information.Abbreviations and symbols are used to show a largeamount of information in a small space.

While there is some standardization of symbolsand abbreviations, a lot of variation still exists. A keyor legend is put on the blueprint to explain their uses.

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An abbreviation is a shortened form of a word.Sometimes the same abbreviation is used for differentwords. The specific meaning of an abbreviation can bedetermined by its use on the blueprint. Abbreviationsare used in notes or as specific characters on theblueprints. The area referred to will give a hint to themeaning of the abbreviation.

Symbols are used on blueprints to representmaterials, equipment, electrical. mechanical, plan.elevations, and sections (figs. 2-2 through 2-9). Theyare used as a simple way of representing a fact. Mostdrawings have a legend of symbols which, whencombined together with the specifications, describes abuilding thoroughly.

SCHEDULES

The schedule is a systematic method of presentingnotes and information in a tabular form for the purposeof making it easily accessible to the craftsman andspecification writer. One example of a commonly usedlighting fixture schedule is shown in figure 2-10.Similar schedules such as the room finish schedule andthe mechanical equipment schedule (not shown) arevery helpful and also should be reviewed.

SCALE REPRESENTATION

An architect cannot make his drawings full size.For convenience. he reduces all dimensions to some

Figure 2-2.—Electrical symbols.

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Figure 2-3.—Additional electrical symbols.

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Figure 2-4.—Heating, plumbing and pipe fitting/value symbols.

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Figure 2-5.—Mechanical and plumbing symbols.

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Figure 2-6.—Architectural symbols for doors and windows.

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Figure 2-7.—Title symbols.

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Figure 2-8.—Architectural symbols for plans and elevations.

scale. He selects some smaller dimension to represent afoot and reduces all dimensions to this unit. A floorplan or an elevation is often drawn at l/48 the size ofthe real building. A drawing 1/48th size would bedrawn at a scale of 1/4" = 1'0". Each l/4 inch on thedrawing equals 1 foot on the actual building. Differentscales are used to show different areas of the drawings.While floor plans and elevations are commonly drawnl/4" = 10, detail drawings are drawn at a larger scale,usually 1" = 10. Sometimes full-scale drawings areused to show a small detail. The scale is normally notedin the title block or beside each drawing on the print.

Scaled drawings are made using an architect’sscale (fig. 2-11). An architect’s scale has 11 scales(table 2-2). The numbers at each end of thearchitect’s scale designate the scale. Figure 2-12

shows an enlarged view of part of a l/4-inch scale.Each division on the scale equals 1 foot on the actualbuilding. The small divisions to the right equal 1inch on the building, thereby allowing more accuratemeasurement. This scale is read from right to left.Architects and drafters use an architectural scale todraw blueprints. Figure 2-13 shows how the scale isused to check a measurement on a blueprint. Notehow the small divisions (at the right) are used to getexact measurements; in this case, 8 feet 8 inches.

MODULAR DIMENSIONS

Some blueprints are drawn so that features on thestructure fall within a set module or measure. Amodular system is based upon a grid with a setmeasure, normally 4 inches or a multiple of 4 inches,such as 16. 24, or 48 inches. Walls, floor levels, and

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Figure 2-9.—Plot plan, contours, and symbols.

openings are dimensioned to fall on 4-inch modularlines. This approach reduces building costs bycoordinating building sizes with standard-sizedbuilding materials. For example, studs with finish areapproximately 4 inches thick and are spaced on 16- or24-inch centers. Plywood panels and drywall sheetscome in standard 4-foot by 8-foot sheets.

Figure 2-14 shows a modular light-frame houseused for a small residential building. The building islaid out in such a way that standard modular-basedbuilding materials can be used. Often, modular

construction is used to develop complete, finishedpanels or rooms. This process allows standard-sizebuilding parts to be fabricated, taken to the buildingsite, and erected into place.

METRIC DIMENSIONS

Metric measurement is becoming more commonin the United States on construction working drawings.NAVFAC drawings now have dimensions in bothmetric and English. The metric scale is used in place ofthe architect’s and engineer’s scales when measure-ments and dimensions are in meters and centimeters.

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Figure 2-10.—Commonly used lighting fixture.

Table 2-2.—Architect’s Scales

SCALE RELATION OF SCALE TO OBJECT

16

3

Full Scale

3" = 1'-0"

1 l/2 1 1/2" = 1'-0"

1 1" = 1'-0"

3/4 3/4" = 1'-0"

l/2 1/2" = 1'-0"

3/8 3/8" = 1'-0"

l/4 l/4" = 1'-0"

3/16 3/1" = 1'-0"

l/8 1/8" - 1'-0"

3/32 3/23" = 1'-0"

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Figure 2-11.—Architect’s scale.

Figure 2-12.—Enlarged view of part of a l/4-inch scale.

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Figure 2-13.—Using a scale to check a measurement on a blueprint.

Figure 2-14.—Exploded view of a typical light-frame modular house.

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When you are using scales on a drawing, do notconfuse the engineer’s scale with a metric scale. Theyare very similar in appearance. You will often findmetric dimensions used on blueprints from othercountries. Metric drawings are dimensioned inmillimeters (mm). There are 25.4 millimeters to aninch. A meter is 39.37 inches, a few inches longer thana yard measure.

Scales of 1:100 and 1:200 are common scales formetric drawings. One millimeter on the drawingrepresents 100 or 200 millimeters on the actualbuilding.

Metric blueprints developed in the United Statesare normally marked “METRIC.” In countries thatuse metric, however, no metric notations are made.

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CHAPTER 3

GENERATORS

INTRODUCTION

As a Construction Electrician, you may have theresponsibility for the installation, maintenance, andrepair of electrical power generation equipment. Intime of war or national emergency, Advanced BaseFunctional Components (ABFC) will normally beused at temporary overseas bases. Even in peacetime,generation equipment is used at remote bases or asemergency and backup power on most naval bases.

A power distribution system includes all partsof an electrical system between the power sourceand the load. This chapter gives the correct proceduresfor the operation and maintenance of power plants anddistribution systems and presents technical informa-tion for the selection and installation of power-generating plants.

POWER GENERATION

The characteristics built into naval electricalinstallations are simplicity, ruggedness, reliability,and flexibility to permit continued service. It is thefunction of those who operate these plants to make fulluse of the installation’s inherent capabilities and tomaintain, as far as possible, uninterrupted availabilityof electrical power where it is needed. To be able to dothis, operating personnel should possess the following:

A thorough knowledge of how to operate andmaintain the components of an electrical plant

A complete familiarity with the electrical plantsdistribution capabilities

An understanding of the electrical systemoperation of the base

The ability to apply electrical and electronicprinciples to specific installations

The sizing and installation of secondaryconductors

EMERGENCY/STANDBY POWER

When you set up an emergency/standby powersystem, numerous factors must be considered. Thefollowing text will cover a few of the possible

situations you may encounter. This chapter does notinclude the automatic transfer aspect of switching tobackup power, since this task is performed by some-one with a Navy Enlisted Classification (NEC) code,CE-5601 Uninterruptible Power Supply (UPS). Forour discussion in this section, we will be using the termemergency-the concepts involved are equallyapplicable to “standby” systems. Remember that theNational Electrical Code® requires emergency andstandby systems to be kept entirely separate from allother wiring and equipment. For more detailedinformation, see article 700 of the National ElectricalCode®.

SYSTEM DESIGN

Whether you are designing and installing an emer-gency backup system or operating and maintaining anexisting system, you must be completely familiar withthe installation requirements and the physical charac-teristics of the equipment. The design, material, andinstallation must comply with electrical safetystandards and codes.

In general, when emergency power is discussed,it is assumed to be replacing “normal” power. Thechoice of arrangement and the size and the type ofequipment depend in large measure on the loads to befed from the emergency system. The system includesall devices, wiring, raceways, transfer switch, energysource, and other electrical equipment required tosupply power to selected loads. These selected loadswill be determined by the available power from youremergency power source. Figures 3-1 and 3-2 showtwo possible arrangements for emergency/standbypower hookups.

GENERATOR SELECTION

When an overseas base is first established andelectrical power is required in a hurry, you will nothave time to set up a centrally located generatingstation; instead, you will spot a portable plant at eachimportant location requiring power. Table 3-1 listssome of the standard alternating current (ac)generators available. These standard generators arecapable of meeting the power requirements ofadvanced bases and also those for permanent orportable emergency power.

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Figure 3-2.—Multiple-transfer switches.

The electrical loads to be supplied power, volt-age, phase, frequency, and duty cycle requirementsgovern the selection of generating equipment.Probable load deviation, probable life of theinstallation, availability of fuels, and availability ofskilled personnel are other important factors.

Power and Voltage Requirements

The selection of voltage is affected by the size, thecharacter, and the distribution of the load; length,capacity, and type of transmission and distributioncircuits; and size, location, and connection ofgenerators. Practically all general-purpose lighting inthe United States and at United States overseas bases is120 volts. The lighting voltage may be obtained from athree-wire, 120/240-volt, single-phase circuit or a120/208-volt, three-phase, four-wire circuit.

Electrical plants at advanced bases serve a variedload of lighting, heating, and power equipment, mostof which demand power day and night. The annualload factor (the ratio of average power to peak power)of a well-operated active base should be 50 percent ormore with a power factor (explained later in thischapter) of 80 percent or higher. If the load is morethan a few hundred feet from the power source, ahigh-voltage distribution system may be required.

If several generators are to serve primarydistribution systems, they should generate the samevoltage to avoid the need for voltage transformation.The number of phases required by the load may differfrom that produced by the generator. As loads usuallycan be divided and balanced between phases, mostgenerators of appreciable size are wound for three-phase operation.

Small motors can be supplied by single-phase ac atnormally 120 volts. Large three-phase, ac motorsabove 5 horsepower generally operate satisfactorily atany voltage between 200 and 240. The use of combinedlight and power circuits will be accomplished by theuse of 240- or 208-volt systems.

Computation of the Load

As mentioned earlier in this chapter, there arevarious factors that must be taken into consideration inthe selection of the required generating equipment.The following technical data will help you incomputing the load.

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Table 3-1.—Types of Portable Generators

Alternating current

Frequency

Voltage120/208

120

60-hertz

120/208240/416

Phase 1 l & 3 3

Wires 2 4* 4

Fuel G D G D G D

kW Rating

5 X X X X

10 X X

15 X X

30 X X

X60 X

100 X X

200 X

G—Gasoline driven. D—Diesel driven.*—Panel connections permit, at rated kW output: 120/208V

3-phase 4-wire, 120V 3-phase 3-wire, 120V single-phase2-wire, 120/240V single-phase 3 wire.

Before any part of the system can be designed, theamount of power to be transmitted, or the electricalload, must be determined. Electrical loads are generallymeasured in terms of amperes. kilowatts, orkilovoltamperes. In general, electrical loads areseldom constant for any appreciable time, but fluctuateconstantly. In calculating the electrical load, you mustdetermine the connected load first. The connected loadis the sum of the rated capacities of all electricalappliances, lamps, motors, and so on, connected to thewiring of the system. The maximum demand load is thegreatest value of all connected loads that are inoperation over a specified period of time. Knowledgeof the maximum demand of groups of loads is of greatimportance: because it is the group maximum demandthat determines the size of generators, conductors, andapparatus throughout the electrical system.

The ratio between the actual maximum demandand the connected load is called the DEMANDFACTOR. If a group of loads were all connected to thesupply source and drew their rated loads at the sametime, the demand factor would be 1.00. There are twomain reasons why the demand factor is usually lessthan 1.00. First, all load devices are seldom in use atthe same time and, even if they are, they will seldomreach maximum demand at the same time. Second,some load devices are usually slightly larger than theminimum size needed and normally draw less thantheir rated load. Since the maximum demand is one ofthe factors determining the size of conductors, it isimportant that the demand factor be established asclosely as possible.

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The demand factor varies considerably fordifferent types of loads. services, and structures. TheNational Electrical Code®. Article 220. provides therequirements for determining demand factors.Demand factors for some military structures are givenin table 3-2.

Example: A machine shop has a total connectedload of 50.3 kilowatts. The demand factor for this typeof structure is taken at 0.70. The maximum demand is50.3 × 0.70 = 35.21 kilowatts.

GENERATOR INSTALLATION

Generators are not permitted to be closer than 25feet to a load; however, in setting up the generator, tryto place the equipment near points of large demand toreduce the size of wire required: to hold the line lossesto a minimum. and to afford adequate voltage controlat the remote ends of the lines.

Moving the generator may be accomplished bylifting or pulling. The generator set comes equippedwith a lifting sling usually stored in the skid on the sideof the unit opposite the operator’s control panel.

Site Selection

You should study a plot or chart of the area onwhich the individual buildingsand facilities have beenplotted. The site you select should be large enough tomeet present and anticipated needs. Then select alocation where there will be sufficient space on allsides for servicing and operation of the unit. It shouldbe level. dry, and well drained. If this type of site is notavailable, place the generator set on planks, logs, orother material for a suitable base foundation.

Table 3-2.—Demand Factor

Structure Demand Factor

HousingAircraft maintenance facilitiesOperation facilitiesAdministrative facilitiesShopsWarehousesMedical facilities

Theaters

NAV aidsLaundry, ice plants, and bakeriesAll others

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0.9.7.8.8.7.5.8.5

.51.0

.9

Sheltering of Generators

Although advanced base portable generators aredesigned to be operated outdoors, prolonged exposureto wind. rain. and other adverse conditions willdefinitely shorten their lives. If the generators are toremain on the site for any extended period of time, theyshould be mounted on solid-concrete foundations andinstalled under some type of shelter.

Presently, there are no predrawn plans for sheltersfor a small advanced base generating station. Theshelter will be an on-the-spot affair, the construction ofwhich is determined by the equipment and material onhand plus your ingenuity and common sense.

Before a Builder can get started on the shelter, youwill have to inform him of such things as the number ofgenerators to be, sheltered; the dimensions of thegenerators; the method of running the generator loadcables from the generator to the distribution systemoutside the building; and the arrangement of theexhaust system, radiator discharge, and cooling air.Installation specifications are available in themanufacturer’s instruction manual that accompanieseach unit. Be sure to use them. Appropriateconsultation with the Builder regarding these speci-fications may help minimize various installation andpiping problems and costs.

The following hints and suggestions also will behelpful:

1. Ventilation is an important factor to considerwhen you are installing the units inside a building.Every internal combustion engine is a HEAT engine.Although heat does the work, excess amounts of heatmust be removed if the engine is to function properly.Heat can be removed by setting the engine radiatorgrille near an opening in the wall and providing anotheropening directly opposite the unit. In this manner, coolair can be drawn in and the hot air directed outdoors.These openings can be shielded with adjustable louversto prevent the entrance of rain, sand, or snow. Inaddition, when the engine is operating in extremely coldweather. the temperature in the room can be controlledby simply closing a portion of the discharge opening.Additional doors or windows should be provided in theshelter if the plants are installed in localities where thesummer temperatures exceed 80°F at any time.

2. Working space is another consideration. Be sureto provide sufficient space around each unit for repairsor disassembly and for easy access to the generatorcontrol panels.

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3. The carbon monoxide gas present in the exhaustof the engine is extremely poisonous. Under nocircumstances should this gas be allowed to collect in aclosed room; therefore, means have to be provided todischarge the engine exhaust to the outdoors. Exhaustcan be vented by extending the exhaust pipe through thewall or roof of the building. Support the exhaust pipeand make certain that there is no obstruction and avoidright-angle bends, ifpossible. Also, whenever possible,arrange the exhaust system so that the piping slopesaway from the engine. In this way, condensation willnot drain back into the cylinders. If the exhaust pipeshould have to be installed so that loops or traps arenecessary, a drain cock should be placed at the lowestpoint of the system. All joints have to be perfectly tight;and where the exhaust pipe passes through the wall, youhave to prevent the discharged gas from returning alongthe outside of the pipe back into the building. Exhaustpiping inside the building has to be covered withinsulation capable of withstanding a temperature of1500°F.

After the generating units have been set in placeand bolted down, Builders then can proceed to erect thebuilding, using the necessary information provided bythe CEs.

Generator Set Inspection

After setting up a portable generator, your crewmust do some preliminary work before placing thegenerator in operation. First, they should make anoverall visual inspection of the generator. Have themlook for broken or loose electrical connections, bolts,and cap screws; and see that the ground terminal wire(No. 6 AWG minimum ) is properly connected to theground rod/grounding system. Check the technicalmanual furnished with the generator for wiring diagrams,voltage outputs, feeder connections, and prestartpreparation. If you find any faults, you should correctthem immediately.

Generator Connections

When you install a power plant that has a dual-voltage alternator unit, make certain that the stator coilleads are properly connected to produce the voltagerequired by the equipment.

Proper grounding is also a necessity for personnelsafety and for prevention of unstable, fluctuatinggenerator output.

INTERNAL LEADS. —The voltage changeoverboard permits reconnection of the generator phase

windings to give all specified output voltages. One endof each coil of each phase winding runs from thegenerator through an instrumentation and a staticexciter current transformer to the reconnection panel.This routing assures current sensing in each phaseregardless of voltage connection at the reconnectionboard assembly. The changeover board assembly isequipped with a voltage change board to facilitateconversion to 120/208 or 240/416 generator outputvoltage. Positioning of the voltage change boardconnects two coils of each phase in series or in parallel.In parallel, the output is 120/208; in series, the output is240/416 volts ac. The terminals on the changeoverboard assembly for connection to the generator loadsare numbered according to the particular coil end ofeach phase of the generator to ensure properconnections.

Remember that you are responsible for the properoperation of the generating unit; therefore, proceedwith caution on any reconnection job. Study the wiringdiagrams of the plant and follow the manufacturer’sinstructions to the letter. Before you start the plant upand close the circuit breaker, double-check allconnections.

GROUNDING.—It is imperative that you solidlyground all electrical generators operating at 600 voltsor less. The ground can be, in order of preference, anunderground metallic water piping system, a drivenmetal rod, or a buried metal plate. A ground rod has tohave a minimum diameter of 5/8 inch if solid and 3/4 inchif pipe, and it has to be driven to a minimum of 8 feet. Aground plate has to be a minimum of 2 square feet and beburied at a minimum depth of 2 l/2 feet. For the groundlead, use No. 6 AWG copper wire and bolt or clamp it tothe rod, plate, or piping system. Connect the other end ofthe ground lead to the generator set ground stud.

The National Electrical Code® states that a singleelectrode consisting of a rod, pipe, or plate that does nothave a resistance to ground of 25 ohms or less will beaugmented by additional electrodes. Where multiple rod,pipe, or plate electrodes are installed to meet therequirements, they are required to be not less than 6 feetapart.

It is recommended that you perform an earthresistance test before you connect the generator toground. This test will determine the number of groundrods required to meet the requirements, or it may benecessary to construct a ground grid.

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Feeder Cable Connections

While the electric generator is being installed andserviced, a part of your crew can connect it to the load.Essentially, this connection consists of running wire orcable from the generator to the load. At the load end,the cable is connected to a distribution terminal. At thegenerator end, the cable is connected either to theoutput terminals of a main circuit breaker or a loadterminal board. Before the wires are run andconnections are made, it will be up to you to do thefollowing:

1. Determine the correct size of wire or cable touse.

2. Decide whether the wire or cable will be buried,carried overhead on poles, or run in conduit.

3. Check the generator lead connections of theplant to see that they are arranged for the propervoltage output.

The information contained in the followingparagraphs will help you in these tasks.

CABLE SELECTION. —If the wrong size con-ductor is used in the load cable, various troubles mayoccur. If the conductor is too small to carry the currentdemanded by the load, it will heat up and possiblycause a fire or an open circuit. Even though the con-ductor is large enough to carry the load current safely,its length might result in a lumped resistance thatproduces an excessive voltage drop. An excessivevoltage drop results in a reduced voltage at the loadend. This voltage drop should not exceed 3 percent forpower loads, 3 percent for lighting loads, or 6 percentfor combined power and lighting loads.

Select a feeder conductor capable of carrying 150per cent of rated generator amperes to eliminate over-loading and voltage drop problems. Refer to theNational Electrical Code® tables for conductorampacities. These tables are 310-16, 310-17, 310-18,and 310-19. You also should refer to the notes toampacity tables following table 310-19.

CABLE INSTALLATION. —The load cablemay be installed overhead or underground. In anemergency installation, time is the important factor. Itmay be necessary to use trees. pilings, 4 by 4s, or othertemporary line supports to complete the installation.Such measures are temporary; eventually, you willhave to erect poles and string the wire or bury itunderground. If the installation is near an airfield, itmay be necessary to place the wires underground at the

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beginning. Wire placed underground should be direct-burial. rubber-jacketed cable: otherwise, it will not lastlong.

Direct burying of cable for permanent installationcalls for a few simple precautions to ensure uninterruptedservice. They are as follows:

1. Dig the trench deep enough so that the cable canbe buried at least 18 inches (24 inches in traffic areasand under roadways) below the surface of the ground toprevent disturbance of the cable by frost or subsequentsurface digging.

2. After laying the cable and before backfilling,cover it with soil free from stones, rocks. and so forth.That will prevent the cable from being damaged in theevent the surrounding soil is disturbed by flooding orfrost heaving.

GENERATING PLANT OPERATIONS

When you are in charge of a generating station,you will be responsible for scheduling around-the-clock watches to ensure a continuous and adequateamount of electrical power. Depending on the numberof operating personnel available, the watches areevenly divided over the 24-hour period. A commonpractice is to schedule 6-hour watches, or they may bestretched to 8-hour watches without working unduehardship on the part of the crew members. Watchesexceeding 8 hours, however, should be avoided unlessemergency conditions dictate their use.

The duties assigned to the personnel on generatorwatches can be grouped into three main categories: (1)operating the equipment, (2) maintaining theequipment, and (3) keeping the daily operating log.Operating and maintaining the generating equipmentwill be covered in the succeeding sections of thischapter, so for the present you can concentrate on theimportance of the third duty of the stationoperator—keeping a daily operating log.

The number of operating hours are recorded in thegenerating station log. The log serves as a basis fordetermining when a particular piece of electricalequipment is ready for inspection and maintenance.The station log can be used in conjunction withprevious logs to spot gradual changes in equipmentcondition that ordinarily are difficult to detect in day-to-day operation. It is particularly important that youimpress upon your watch standers the necessity fortaking accurate readings at periods specified by localoperating conditions.

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Ensure that watch standers keep their spaces cleanand orderly. Impress on them the importance ofkeeping tools and auxiliary equipment in their properplaces when not in use. Store clean waste and oilywaste in separate containers. OILY WASTECONTAINERS ARE REQUIRED TO BE KEPTCOVERED. Care given to the station floor will begoverned by its composition. Generally, it should beswept down each watch. Any oil or grease that istracked around the floor should be removed at once.

Plant Equipment

Setting up a power generator is only one phase ofyour job. After the plant is set up and ready to go, youwill be expected to supervise the activities of theoperating personnel of the generating station. In thisrespect, your supervision should be directed towardone ultimate goal-to maintain a continuous andadequate flow of electrical power to meet the demand.That can be accomplished if you have a thoroughknowledge of how to operate and maintain theequipment and a complete understanding of thestation’s electrical systems as a whole. Obviously, athorough knowledge of how to operate and maintainthe specific equipment found in the generating stationto which you are assigned cannot be covered here;however, general information will be given. It will beup to you to supplement this information with thespecific instructions given in the manufacturers’sinstruction manuals furnished with each piece ofequipment.

Similarly, familiarity with the station’s electricalsystem as a whole can be gained only by a study ofinformation relating specifically to that installation.This information can be found to some extent in themanufacturer’s instruction manuals. You can obtainthe greater part of it from the station’s electrical plansand wiring diagrams. Remember, however, to sup-plement your study of the electrical plans and diagramswith an actual study of the generating station’s system.In that way, the generators, switchgear, cables, andother electrical equipment are not merely symbols on aplan but physical objects whose location is definitelyknown and whose functions and relation to the rest ofthe system are thoroughly understood.

Single Plant Operation

Connecting an electric plant to a de-energized businvolves two general phases: (1) starting the dieselengine and bringing it up to rated speed under controlof the governor and (2) operating the switchboard

controls to bring the power of the generator onto thebus.

Different manufacturers of generating plantsrequire the operator to perform a multitude of stepsbefore starting the prime mover; for example, if adiesel engine is started by compressed air, the operatorwould have to align the compressed air system. Thisalignment would not be necessary if the engine is of theelectric-start type. It is important that you, as the plantsupervisor, establish a prestart checklist for eachgenerating plant. The prestart checklist provides amethodical procedure for confirming the operationalconfiguration of the generating plant; following thisprocedure assures that all systems and controls areproperly aligned for operation.

The checklist should include, but is not limited to,the following:

1.

2.

3.

4.

5.

6.

Align ventilation louvers.

Check lube oil, fuel oil, and cooling waterlevels.

Ensure battery bank is fully charged.

Align electrical breakers and switches forproper operation of auxiliary equipment.

Check control panel and engine controls.

Select the proper operating position for thefollowing controls for single plant operation.

Voltage regulator switch to UNIT or SINGLEposition.

Governor switch to ISOCHRONOUS orSINGLE position.

NOTE: Adjust hydraulic governor droop positionto 0.

Voltage regulator control switch to AUTOposition.

The prestart checklist should be completed insequence before you attempt to start the generatingplant.

Start the generating plant and adjust the enginerpm to synchronous speed. Adjust the voltageregulator to obtain the correct operating voltage. Setthe synchronizing switch to the ON position and closethe main circuit breaker. Adjust the frequency to 60hertz with the governor control switch. Perform hourlyoperational checks to detect abnormal conditions andto ensure the generating set is operating at the correctvoltage and frequency.

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Parallel Plant Operation

If the load of a single generator becomes so largethat its rating is exceeded, you should add anothergenerator in parallel to increase the power available forthe generating station. Before two ac generators can beparalleled, the following conditions have to befulfilled:

1. Their terminal voltages have to be equal.

2. Their frequencies have to be equal.

3. Their voltages have to be in phase.

When two generators are operating so that therequirements are satisfied, they are said to be insynchronism. The operation of getting the machinesinto synchronism is called synchronizing.

Generating plants may be operated in parallel onan isolated bus (two or more generators supplyingcamp or base load) or on an infinite bus (one or moregenerators paralleled to a utility grid).

One of the primary considerations in parallelinggenerator sets is achieving the proper division of load.That can be accomplished by providing the governorof the generator with speed droop. That would result ina regulation of the system. The relationship ofREGULATION to LOAD DIVISION is bestexplained by referring to a speed versus load curve ofthe governor. For simplicity,. we will refer to thenormal speed as 100 percent speed and full load as 100percent load. In the controlled system, we will beconcerned with two types of governor operations:isochronous and speed droop.

The operation of the isochronous governor (0percent speed droop) can be explained by comparingspeed versus load. as shown in figure 3-3. If thegovernor were set to maintain the speed represented byline A and connected to an increasing isolated load, thespeed would remain constant. The isochronousgovernor will maintain the desired output frequency,regardless of load changes if the capacity of the engineis not exceeded.

The speed-droop governor (100 percent speeddroop) has a similar set of curves. but they are slanted.as shown in figure 3-4. If a speed-droop governor wereconnected to an increasing isolated load, the speedwould drop (line A. fig. 3-4) until the maximum enginecapacity is reached.

Now let’s imagine that we connect the speed-droop governor (slave machine) to a utility bus so largethat our engine cannot change the bus frequency (an

Figure 3-3.—Isochronous governor curve.

Figure 3-4.—Speed-droop governor curve.

infinite bus). Remember that the speed of the engine isno longer determined by the speed setting but by thefrequency of the infinite bus. In this case, if we shouldchange the speed setting, we would cause a change inload, not in speed. To parallel the generator set, we arerequired to have a speed setting on line A (fig. 3-4). atwhich the no-load speed is equal to the bus frequency.Once the set is paralleled. if we increase the speedsetting to line B. we do not change the speed. but wepick up approximately a half-load. Another increase inspeed setting to line C will fully, load the engine. If thegenerator set is fully loaded and the main breaker is

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opened, the no-load speed would be 4 percent abovesynchronous speed. This governor would be defined ashaving 4 percent speed droop.

Paralleling an isochronous governor to an infinitebus would be impractical because any difference inspeed setting would cause the generator load to changeconstantly. A speed setting slightly higher than the busfrequency would cause the engine to go to full-loadposition. Similarly, if the speed setting were slightlybelow synchronous speed, the engine would go to no-load position.

Setting speed droop on hydraulic governors isaccomplished by adjusting the speed-droop knoblocated on the governor body. Setting the knob toposition No. 5 does not mean 5 percent droop. Each ofthe settings on the knob represents a percentage of thetotal governor droop. If the governor has a maximumof 4 percent droop. the No. 5 position would be 50percent of 4 percent droop. Setting speed droops onsolid-state electronic governors is accomplished byplacing the UNIT-PARALLEL switch in thePARALLEL position. The governor speed droop isfactory set, and no further adjustments are necessary.

ISOLATED BUS OPERATION. —In thefollowing discussion, assume that one generator, calledthe master machine, is operating and that a secondgenerator, called the slave machine, is beingsynchronized to the master machine. Governor con-trols on the master ernogenerator should be set to theISOCHRONOUS or UNIT position. The governorsetting on the slave generator must be set to thePARALLEL position.

NOTE: The hydraulic governor droop setting is anapproximate value. Setting the knob to position No. 5 willallow you to parallel and load the generator set. Minoradjustments may be necessary to prevent load swingsafter the unit is operational.

When you are paralleling in the droop mode withother generator sets, the governor of only one set maybe in the isochronous position; all others are in thedroop position. The isochronous set (usually thelargest capacity set) controls system frequency andimmediately responds to system load changes. Thedroop generator sets carry only the load placed on themby the setting of their individual speed controls. Bothvoltage regulators should be set for parallel andautomatic operation.

The slave machine is brought up to the desiredfrequency by operating the governor controls. It ispreferable to have the frequency of the slave machine

slightly higher than that of the master machine toassure that the slave machine will assume a smallamount of load when the main circuit breaker is closed.Adjust the voltage controls on the slave machine untilthe voltage is identical to that of the master machine.Thus two of the requirements for synchronizing havebeen met: ‘frequencies are equal and terminal voltagesare equal.

There are several methods to check generatorphase sequence. Some generator sets are equippedwith phase sequence indicator lights and a selectorswitch labeled “GEN” and “BUS.” Set the PHASESEQUENCE SELECTOR SWITCH in the BUSposition, and the “1-2-3” phase sequence indicatinglight should light. (The same light must light in eitherGEN or BUS position.) If “3-2-1” phase sequence isindicated, the slave machine has to be shut down, theload cables isolated, and two of the load cablesinterchanged at their connection to the load terminals.

Another method to verify correct phase sequenceis by using the synchronizing lights. When thesynchronizing switch is turned on, the synchronizinglights will start blinking. If the synchronizing lightsblink on simultaneously and off simultaneously, thevoltage sequences of the two machines are in phase.The frequency at which the synchronizing lights blinkon and off together indicates the different frequencyoutput between the two machines. Raise or lower thespeed of the slave machine until the lights blink ontogether and offtogether at the slowest possible rate. Ifthe synchronizing lights are alternately blinking (oneon while the other is off), the voltage sequence of thetwo machines is not in phase. Correct this condition byinterchanging any two of the three load cablesconnected to the slave machine.

Some of the portable generators being placed inthe NMCB Table of Allowances (TOA) are equippedwith a permissive paralleling relay. This relay, wiredinto the main breaker control circuit, prevents theoperator from paralleling the generator until all threeconditions have been met.

Now that all three paralleling requirements havebeen met, the slave machine can be paralleled andloaded.

If a synchroscope is used, adjust the frequency ofthe slave machine until the synchroscope pointerrotates clockwise slowly through the ZERO position(twelve o’clock). Close the main circuit breaker justbefore the pointer passes through the ZERO position.To parallel using synchronizing lights, wait until the

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lamps are dark; then, while the lamps are still dark,close the main circuit breaker and turn off thesynchronizing switch.

After the main breaker has been closed, check andadjust the load distribution by adjusting the governorspeed control. Maintain approximately one-half loadon the master machine by manually adding orremoving the load from the slave machine(s). Themaster machine will absorb all load changes andmaintain correct frequency unless it becomesoverloaded or until its load is reduced to zero.

The operator also must ensure that all generatingsets operate at approximately the same power factor(PF). PF is a ratio, or percentage, relationship betweenwatts (true power) of a load and the product of voltsand amperes (apparent power) necessary to supply theload. PF is usually expressed as a percentage of 100.Inductive reactance in a circuit lowers the PF bycausing the current to lag behind the voltage. Low PFscan be corrected by adding capacitor banks to thecircuit.

Since the inductive reactance cannot be changed atthis point, the voltage control rheostat has to beadjusted on each generator to share the reactive load.This adjustment has a direct impact on the generatorcurrent, thus reducing the possibility of overheatingthe generator windings.

Emergency Shutdown

3-10

PF adjustment was not discussed in the “SinglePlant Operation” section because a single generatorhas to supply any true power and/or reactive load thatmay be in the circuit. The single generator must supplythe correct voltage and frequency regardless of thepower factor.

INFINITE BUS OPERATION. —Parallelinggenerator sets to an infinite bus is similar to the isolatedbus procedure with the exception that all sets will beslave machines. The infinite bus establishes the gridfrequency; therefore, the governor of each slavemachine has to have speed droop to prevent constantload changes.

In the event of engine overspeed. high jacket watertemperature, or low lubricating oil pressure, the enginemay shut down automatically and disconnect from themain load by tripping the main circuit breaker. Inaddition, an indicator may light or an alarm may soundto indicate the cause of shutdown. After an emergencyshutdown and before the engine is returned to

operation, the cause of shutdown should beinvestigated and corrected.

NOTE: It is important to check the safety controls atregular intervals to determine that they are in goodworking order.

Basic Operating Precautions

The order that you post in the station for theguidance of the watch standers should include ageneral list of operating rules and electrical safetyprecautions. BE SURE YOU ENFORCE THEM!

The important operating rules are relatively fewand simple. They are as follows:

1. Watch the switchboard instruments. They showhow the system is operating; and they reveal overloads,improper division of kilowatt load or reactive currentbetween generators operating in parallel, and otherabnormal operating conditions.

2. Keep the frequency and voltage at their correctvalues. A variation from either will affect, to someextent at least, the operation of the electrical equipmentof the base. This result is especially true of suchequipment as teletypewriters or electrical clocks. Anelectrical clock and an accurate mechanical clockshould be installed together at the generating station sothat the operators can keep the generators on frequency.

3. Use good judgment when reclosing circuitbreakers after they have tripped automatically; forexample, generally the cause should be investigated ifthe circuit breaker trips immediately after the firstreclosure. However, reclosing of the breaker the secondtime may be warranted if immediate restoration ofpower is necessary and there was no excessiveinterrupting disturbance when the breaker tripped. Itshould be kept in mind, however, that repeated closingand tripping may damage the circuit breaker as well asthe overload vault area, thus increasing the repair orreplacement work.

4. Do not start a plant unless all its switches andbreakers are open and all external resistance is in theexciter field circuit.

5. Do not operate generators at continuousoverload. Record the magnitude and duration of theoverload in the log; record any unusual conditions ortemperatures observed.

6. Do not continue to operate a machine in whichthere is vibration until the cause is found and corrected.Record the cause in the log.

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The electrical safety precautions that should beobserved by the station personnel are as follows:

1. Treat every circuit, including those as low as 24volts, as a potential source of danger.

2. Except in cases of emergency, never allow workon an energized circuit. Take every precaution toinsulate the person performing the work from ground.That may be done by covering any adjacent groundedmetal with insulating rubber blankets. In addition,provide ample illumination, cover working metal toolswith insulating rubber, station men at appropriatecircuit breakers or switches so that the switchboard canbe de-energized immediately in case of emergency, andmake sure all personnel are qualified to render first aid(including CPR) for electric shock.

POWER PLANT MAINTENANCE

Inspection and servicing procedures covered inthis chapter are rather general. In most cases, they canbe applied to any electrical power generator that youinstall. You realize, of course, that there are otherspecial installation details that pertain only to theparticular generator you happen to be working on.Because of the many different types of generators,certain instructions are applicable only to specifictypes of generators; therefore, you should consult themanufacturer’s instruction manuals for these details.

Power plant maintenance can be divided into twogeneral categories: operator maintenance and preven-tive maintenance.

Operator Maintenance

Operator maintenance includes the hourly, daily,and weekly maintenance requirements recommended

in the manufacturer’s literature. Some operatormaintenance and routine checks include the following:

Bring oil level to the high mark on the dip stick.

Free movement of ventilation louvers.

Drain water and sediment from strainers andfilters.

Maintain level of coolant.

Check radiator and coolant hoses for leaks.

Check battery electrolyte level.

Check all switches for proper operation.

Drain water from fuel tank.

Fill fuel tank as required with appropriate dieselfuel.

Check fuel tank for leaks.

Log all operator maintenance in the operations logbook when it is completed.

Preventive Maintenance

Preventive maintenance includes the monthly,quarterly, semiannual, and annual maintenance checksrecommended in the manufacturer’s literature. Themaintenance supervisor is responsible for establishinga maintenance schedule to ensure the preventive main-tenance is performed. A maintenance log book shouldbe established for each generator plant and all mainten-ance checks recorded. The operation log book shouldbe reviewed periodically to ensure that all preventivemaintenance recommended by engine operating hoursis scheduled; for example, the schedule of engine lubeoil and filter replacement is normally based on hours ofoperation.

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CHAPTER 4

ELECTRICAL DISTRIBUTION

INTRODUCTION

As a Construction Electrician second class, youmay have to supervise the installation, maintenance,and repair of overhead primary and secondary powerdistribution systems. This chapter will provide thenecessary information to enable you to calculateelectrical loads and perform fundamental tasks in theselection, by size and type, of distribution equipment.When you perform the above-mentioned tasks,remember, your primary goal should be the safety ofyour troops.

A power distribution system includes all parts ofan electrical system between the power source and thecustomer’s service entrance. The power source may beeither a local generating plant or a high-voltagetransmission line feeding a substation that reduces thehigh voltage to a voltage suitable for local distribution.At most advance bases, the source of power will begenerators connected directly to the load.

DISTRIBUTION SYSTEMSCONFIGURATION

The configurations of four distribution systems aredefined in the following paragraphs. These fourdistribution systems — radial, loop (ring), network,and primary selective — are briefly described. Foradditional information, review the Electric PowerDistribution Systems Operations, NAVFAC MO-201.

RADIAL DISTRIBUTION SYSTEM

A representative schematic of a radial distributionsystem is shown in figure 4-1. You should note that theindependent feeders branch out to several distributioncenters without intermediate connections betweenfeeders.

The most frequently used system is the radialdistribution system because it is the simplest and leastexpensive system to build. Operation and expansionare simple. It is not as reliable as most systems unlessquality components are used. The fault or loss of acable, primary supply, or transformer will result in anoutage on all loads served by the feeder. Furthermore,electrical service is interrupted when any piece of

Figure 4-1.—Radial distribution system.

service equipment must be de-energized to performroutine maintenance and service.

Service on this type of feeder can be improved byinstalling automatic circuit breakers that will reclosethe service at predetermined intervals. If the faultcontinues after a predetermined number of closures,the breaker will lock out until the fault is cleared andservice is restored by hand reset.

LOOP/RING DISTRIBUTION SYSTEM

The loop, or ring, system of distribution starts atthe substation and is connected to or encircles an areaserving one or more distribution transformers or loadcenters. The conductor of the system returns to thesame substation.

The loop system (fig. 4-2) is more expensive tobuild than the radial type, but it is more reliable. It maybe justified in an area where continuity of service is ofconsiderable importance, for example, a medicalcenter.

In the loop system, circuit breakers sectionalizethe loop on both sides of each distribution transformerconnected to the loop. The two primary feeder breakersand the sectionalizing breakers associated with theloop feeder are ordinarily controlled by pilot wirerelaying or directional overcurrent relays. Pilot wirerelaying is used when there are too many secondarysubstations to obtain selective timing with directionalovercurrent relays.

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Figure 4-2.—Loop, or ring, distribution system.

A fault in the primary loop is cleared by thebreakers in the loop nearest the fault, and power issupplied the other way around the loop withoutinterruption to most of the connected loads. Becausethe load points can be supplied from two or moredirections, it is possible to remove any section of theloop from service for maintenance without causing anoutage at other load points. If a fault occurs in a sectionadjacent to the distribution substation, the entire loadmay have to be fed from one side of the loop untilrepairs are made. Sufficient conductor capacity mustbe provided in the loop to permit operation withoutexcessive voltage drop or overheating of the feederwhen either side of the loop is out of service. If a fault

occurs in the distribution transformer, it is cleared bythe breaker in the primary leads; and the loop remainsintact.

NETWORK DISTRIBUTION SYSTEM

The network and radial systems differ with respectto the transformer secondaries. In a network system (fig.4-3) transformer secondaries are paralleled; in a radialsystem, they are not.

The network is the most flexible type of primarysystem; it provides the best service reliability to thedistribution transformers or load center, particularlywhen the system is supplied from two or moredistribution substations. Power can flow from anysubstation to any distribution transformer or loadcenter in the network system. The network system ismore flexible with regard to load growth than the radialor loop system and is adaptable to any rate of loadgrowth. Service readily can be extended to additionalpoints of usage with relatively small amounts of newconstruction. The network system, however, requireslarge quantities of equipment and extensive relaying;therefore, it is more expensive than the radial system.From the standpoint of economy, the network systemis suitable only in heavy-load-density areas where theload center units range from 1,000 to 4,000kilovoltamperes (kVA).

Figure 4-3.—Network distribution system.

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The transformers of a secondary networkdistribution system are connected in parallel through aspecial type of circuit breaker, called a networkprotector, to a secondary bus. Radial secondary feedersare tapped from the secondary bus to supply loads. Amore complex network is a system in which the low-voltage circuits are interconnected in the form of a gridor mesh.

If a primary feeder fails or a fault occurs on aprimary feeder or distribution transformer, the othertransformers start to feed back through the networkprotector on the faulted circuit. This reverse powercauses the network protector to open and disconnectthe faulty supply circuit from the secondary bus. Thenetwork protector operates so fast that there is minimalexposure of secondary equipment to the associatedvoltage drop.

PRIMARY SELECTIVE SYSTEM

In some instances, a higher degree of reliabilitycan be attained with a primary selective system.Protection against loss of a primary supply can begained through the use of a primary selective system(fig. 4-4). Each unit substation is connected to twoseparate primary feeders through switching equipmentto provide a normal and an alternate source. When thenormal source feeder is out of service for maintenanceor a fault, the distribution transformer is switched,

either manually or automatically, to the alternatesource. An interruption will occur until the load istransferred to the alternate source. Cost is somewhathigher than the radial system because primary cableand switchgear are duplicated.

In laying out a distribution system for a base, youshould divide the base into a number of sections. Thesesections should be chosen so that the load in eachsection is close to one of the distribution centers. Youtake this action to keep the length of the mains as shortas possible and to keep the voltage drop low betweenthe distribution and the loads. The distribution or loadcenters should be located as near as possible to theelectrical load center.

OVERHEAD CONSIDERATIONS

In the construction and maintenance of Navypower distributions systems, you should be aware ofthe overhead distribution pole locations and the typesof overhead distribution equipment used. An excellentsource of information on distribution systems is TheLineman’s and Cableman’s Handbook.

POLE LOCATIONS

Your decision on the location of poles is limitedbecause either you will be replacing existing poles orinstalling additional poles according to NAVFAC

Figure 4-4.—Primary selective distribution system.

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drawings and specifications. You may be asked tosubmit information (fact-gathering package) on a newpower distribution addition to the base. If so, thefollowing recommended actions need to be considered:

Install utility poles in the same location,especially on upgrade projects.

Install power distribution systems undergroundwhenever possible.

Conduct a survey using a map to chart theterritory where the distribution lines are to berouted (for large areas, aerial photography isfaster and more accurate).

Ensure that the survey map is large enough toclearly show all buildings. roads. streams, hills,ridges. railroads. bridges. and any existingpower and communications lines.

Select the straightest and shortest routewhenever possible.

Route the new distribution system near or in thegeneral direction of future load demands.

Make the distribution system readily accessiblefor construction. inspection, and maintenance byparalleling them to existing streets and highways.

Avoid crossing hills. ridges, and swamp areaswhenever possible to reduce the possibility oflightning and wind damage. These areas alsoincrease costs because additional materials areneeded and maintenance will be more difficult.

Coordinate with communication companies toprevent the induction of interference with theirexisting lines.

Select a route that is away from residential areasand does not damage the environment.

Keep major traffic routes free from primary,circuits. especially in nonindustrial areas.

Keep-distribution lines on the same side of theroad whenever possible.

Avoid blocking driveways, entrances. exits. andfire escapes when installing branch lines or guys.

Locate poles 2 feet from the curb.

Finally. plan for future street-lighting circuits.

EQUIPMENT

4-4

Many different types and makes of overheaddistribution equipment are in use today. This chapterwill cover some of the standard equipment you will

install and maintain, such as poles, transformers,capacitors, interrupting and protective devices.

Poles

Utility poles that support electrical lines must bedesigned to support the conductors, insulators, andshield conductors in a manner that provides adequateelectrical clearances. A safe clearance must bemaintained when the conductor temperature iselevated as a result of a large amount of current flowingin a circuit and also when the conductors are ice coatedor strong winds are blowing.

The three most common types of poles that you willbe working with are wood, reinforced concrete, andsteel. Other types of poles in use are as follows:aluminum, fiber glass, and polysil. As a Seabeeassigned to either a PWC or a battalion, you will beresponsible for ordering, installing, and maintainingtheutility poles.

Power lines supported by wood-pole structures aregenerally considered to be the most economical. In theUnited States, the southern yellow pine, western redcedar, and the Douglas fir are the most commonly usedspecies of tree. All wooden poles are given apreservative treatment (normally pressure treated) toprevent deterioration. The service life of the utility polecan be doubled by preservative treatment. Many of theolder poles now in use were treated with creosote.

CAUTION

Creosote is a toxic compound that irritates theskin and sometimes causes blistering. It is alsocarcinogenic and is being phased out becauseof groundwater contamination problems.Used creosote contaminated poles may not beburned and must be disposed of in EPAapproved landfills. You should use extra carewhen working around poles treated withcreosote, avoid prolonged skin contact, andwash thoroughly after handling. Clothingcontaminated with creosote should belaundered separately from family clothing.

Creosote oil, pentachlorophenol, and chromatedcopper arsenates have been used to provide apreservation treatment of wood poles. Newer poles arenow treated with less toxic chemicals and, therefore,are safer to work with and also easier to climb (becausethe treatment softens the wood). They areenvironmentally acceptable because they do notcontain materials that are toxic to mammals.

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Wooden utility poles are classified by the length,circumference at the top of the pole, and thecircumference measured 6 feet from the bottom ofthe pole. Pole sizes begin at 25 feet and are increasedin 5-foot increments up to 90 feet in length. The poletop circumference increases 2 inches for every class ofpole. There are 10 classes of wooden poles numberedfrom 1 to 10. Class 1 is the smallest and class 10 is thebiggest. The American National Standards Institute’spublication entitled Specifications and Dimensions forWood Poles (ANSI 05.1) provides technical data forwood utility poles.

Distribution Transformers

For long-distance transmission, a voltage higherthan normally generated is required. A step-uptransformer is used to produce the high voltage. Mostelectrical equipment in the Navy uses 120/208 volts.The primary voltage distributed on Navy shoreinstallations, however, is usually 2,400/4,160 and13,800 volts. A distribution transformer (step-down) isrequired to reduce the high-primary voltage to theutilization voltage of 120/208 volts. The various typesof transformer installations are discussed later in thischapter. Regardless of the type of installation orarrangement, transformers must be protected by fusedcutouts or circuit breakers; and lightning arrestersshould be installed between the high-voltage line andthe fused cutouts.

Three general types of single-phase distributiontransformers are in use today. The conventional typerequires a lightning arrester and fuse cutout on theprimary-phase conductor feeding the transformer. Theself-protected (SP) type has a built-in lightningprotector; the completely self-protected (CSP) typehas the lightning arrester and current-overload devicesconnected to the transformer and requires no separateprotective devices. You should review Module 2,Navy Electricity and Electronics Training Series(NAVEDTRA 172-02-00-91) for more informationon transformer theory.

In primary and secondary windings construction,the change in voltage in a transformer depends on thenumber of turns of wire in the coils. The high-voltagewinding is composed of many turns of relatively smallwire, insulated to withstand the voltage applied to thewinding. The secondary winding is composed of a fewturns of heavy copper wire, large enough to carry highcurrent at a low voltage. Figure 4-5 shows a single-phase transformer with secondary windings connectedin series and parallel.

Figure 4-5.—Single-phase transformer with secondarywindings connected in series and parallel.

In a distribution transformer, a secondary coil iswound on each leg of the laminated iron core, and theprimary coil is wound over the secondary coils. Theprimary leads pass through a steel tank and areinsulated from the tank by porcelain bushings. Thesecondary leads are connected to studs on a terminalblock. Copper straps on the secondary terminal blockpermit connecting the two secondary coils in series orin parallel. From the terminal block, three secondaryleads pass through porcelain bushings to the outside ofthe tank. An oil-level line inside the tank marks thelevel to which the tank is filled with transformer oil.

Several methods of cooling transformers are in usetoday, such as self-air cooling, air-blast cooling,liquid-immersed self cooling, and liquid-immersedwater cooling. Self-air cooling types of transformersare simply cooled by surrounding air at atmosphericpressure; the heat is removed by natural convection(normal dissipation of heat by cooling). The self-aircooling transformer is called the dry type oftransformer.

The air-blast cooling transformer has the core andwindings encased in a metal enclosure through whichair is circulated by a blower. This type is used for largepower transformers with ratings from 12,000 to 15,000kVA.

The liquid-immersed self-cooling transformer hasits coils and core completely immersed in transformer

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oil. In large transformers. the tanks have external tubesor external radiators through which the oil circulatesby natural convection caused by the differences in oiltemperature.

The liquid-immersed water-cooling transformer issometimes used where a plentiful supply of cool wateris available. In this type, a coil of copper or brass pipe isinstalled near the top of the tank in the cooling oil.Water is circulated through this coil and carries awaythe heat from the oil as it rises in the tank.

Insulating liquids have high-insulating qualitiesand serve two purposes: first. they insulate the coil, andsecond. they help dissipate the heat generated by theresistance of the windings and eddy currents in the ironcore. If this heat were not removed. the transformerwould operate at excessively high temperatures,which. in turn, would damage or destroy the insulationon the coils.

Two common types of insulating liquids aremineral oil and Askarel®. Mineral oil is a nontoxicinsulating liquid. It is used in different types of high-voltage electrical equipment, such as circuit breakers,switches. and transformers. Mineral oil must be kept inan airtight container, or else sludge will form. Thissludge will settle in the bottom of the tank and slow thenatural transfer of heat. Also the longer mineral oil isleft exposed to air, thegreater the loss of insulationproperties.

Askarel® is a synthetic, nonflammable insulatingliquid. It has other trade names, such as Pyranol®,Inerteen®, Chlorexirol®, and Asbestol®. This liquidmust be handled with care because of its toxic chemicalproperties. Askarel® is used in special transformersfor applications where flammable liquids must beavoided.

Askarel® may have an irritating effect upon theskin. eyes, nose, and lips. It also may irritate skinabrasions or tender areas between the fingers.Askarel® may contain polychlorinated biphenyls(PCBs): a toxic, carcinogenic oily liquid.Transformers tested and found to be contaminatedwith PCBs should have labels on the outside of thetransformer warning of this hazard.

WARNING

If assigned to work on a transformerknown to be contaminated with PCBs,see your supervisor for a Material SafetyData Sheet (MSDS) for hazards and

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precautions. Personal protectiveequipment, such as impermeable glovesand chemical splash goggles, aremandatory.

Avoid prolonged skin contact andwash thoroughly after use.

Avoid breathing vapors.

When removing transformer oil,wear respiratory protection. If youdiscover PCB transformer oil spilled onsoil, immediately notify your supervisorwho must notify environmentalauthorities and summons a trainedhazardous material spill clean-up team.

To protect yourself when handing Askarel®, wearimpermeable gloves. Also wear splashproof goggles.Whenever liquid comes in contact with the skin, washit thoroughly with warm water and soap.

Ensure that the work space is properly ventilatedbefore working on transformers containing Askarel®.

Avoid breathing Askarel® vapors. Wear anapproved organic vapor cartridge respirator whenvapors are present. When removing Askarel® oilwhich is contaminated with PCBs, air respirators maybe necessary.

If a blueprint of a particular transformerinstallation is available to you, your job will becomparatively easy. All construction and electricalspecifications will be worked out for you beforehand,and all you have to do is convert this information into afinished product. However, in some instances, ablueprint will not be available. Then it will be up to youto determine the location and size of the transformerand install it according to the latest specifications. Youshould be familiar with the rules and requirements ofthe most current electrical codes. Be sure to carefullystudy any applicable code requirements beforeinstalling a transformer.

Transformers are mounted on poles in variousways, such as suspended on a bracket bolted to thepole, suspended from a crossarm with brackets, or seton a platform mounted on an H-frame.

Single-phase transformers are usually hung with athrough-bolt type of bracket or a cross-arm type ofbracket. Figure 4-6 shows a single transformer hungwith cross-arm brackets. Figure 4-7 shows a bank ofthree transformers of 25 kVA capacity hung the sameway.

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Figure 4-6.—Single transformer hung with crossarm

brackets.

Figure 4-8.—Three 37.5 kVA transformers mounted withthrough-bolt type of brackets.

Figure 4-7.—Three-phase bank of transformers hung on acrossarm.

Formerly, all banks of three transformers werehung with crossarm brackets or mounted on a platformbetween two poles. Because of improved materials,however, transformer capacities have been enlargedwithout increasing their size and weight. Thisimprovement means that banks of three large trans-formers can now be hung on a pole with a through-boltbracket type of suspension, as shown in figure 4-8.

The old method of mounting transformers on aplatform required an extra pole and the added cost ofbuilding the platform. This method is still used wheninstalling large transformers and in special jobapplications. Figure 4-9 shows the platform method ofmounting a bank of three single-phase, 25 kVAtransformers-Y-connected to obtain single-phaseand three-phase power.

Grounding the distribution system helps to preventaccidents to personnel and damage to property in theevent of insulation breakdown, accidental shorting ofhigh- and low-voltage lines, or a lightning strike.

If a high-voltage line is accidentally shorted with alow-voltage line, the current will flow through thesecondary coil of the transformer to the secondaryground that will then cause the primary protectivedevice to open the circuit. In this case, the primaryprotective device functions as the substation circuitbreaker. An accidental shorting of the primary andsecondary windings in the transformer will cause theprimary fuse to open.

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Figure 4-9.—Three-phase 25 kVA transformers mounted on an H-frame platform.

If there are no ground connections, the primary Great danger will exist for everyone touching anyvoltage will be impressed upon the secondary electrical equipment at this time.

conductors, which are usually, insulated for 600 volts, Ground resistance must not exceed 25 ohms toand considerable damage to the equipment will occur. ground. This resistance can be measured with various

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portable ground-testing instruments, such as a megger.One procedure for measuring ground resistance with amegger is shown in figure 4-10.

If the ground resistance is too high, it may belowered by one of the following methods:

1. Drive additional rods. spacing them 6 feet apart,and then connect them in parallel.

2. Use larger rods where low resistance soils aretoo far below the surface to be reached byordinary rods.

When you are connecting transformers in parallelor in a three-phase bank, it is important to know thepolarity of the transformer terminals or leads. In themanufacturing of transformers, the ends of thewindings are connected to the leads extending outthrough the case. The internal connection determinesthe direction of current flow in the secondary terminalwith respect to the corresponding primary terminal.The current may flow in the same direction or in theopposite direction. When the current flows in theprimary and secondary windings in the same direction,the polarity of the transformer is said to be subtractive;and when the current flows in the opposite directions,the polarity is said to be additive.

Polarity may be further explained as follows:imagine a single-phase transformer having two

high-voltage and three low-voltage external terminals.Connect one high-voltage terminal to the adjacent low-voltage terminal, and apply a test voltage across thetwo high-voltage terminals. If the voltage across theunconnected high-voltage and low-voltage terminalsis less than the test voltage, the polarity is subtractive;if it is greater than the test voltage, the polarity isadditive. This test is shown in figure 4-11.

Figure 4-11.—Polarity tests.

Figure 4-10.—Measuring ground resistance where the ground wire is interconnected with the ground distribution neutralconnector.

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It is apparent that when the voltage indicated on thevoltmeter is greater than the impressed voltage. it mustbe the sum of the primary and the secondary voltages:and the direction of the two windings must be opposite.as shown in figure 4-12. Likewise, when the voltageread on the voltmeter is less than the impressed voltage,the voltage must be the difference of the primary andsecondary voltages, as shown in figure 4-13. When theterminal markings are arranged in the same numericalorder, H1H2 and X1X2 or H2H1 and X2X1. on eachside of the transformer, the polarity of each winding isthe same (subtractive). If either is in reverse order,H2H1 and X1X2 or H1H2 and X2X1. their polaritiesare opposite (additive). The nameplate of a transformershould always indicate the polarity of the transformer.

Additive polarity is standard for all single-phasedistribution transformers 200 kVA and below havinghigh-voltage ratings of 9.000 volts and below.

Subtractive polarity is standard for all single-phasedistribution transformers above 200 kVA irrespectiveof the voltage rating.

Subtractive polarity is standard for all single-phasetransformers 200 kVA and below having high-voltageratings above 9.000 volts.

Figure 4-12.—Polarity markings and directions of voltageswhen polarity is additive.

Figure 4-13.—Polarity markings and directions of voltageswhen polarity is subtractive.

Standard low-voltage terminal designations areshown in figure 4-14.

CAUTION

When you are making such tests. voltage mustnot be applied across the secondary side of thetransformer because the primary voltagewould then be equal to the applied secondaryvoltage multiplied by the transformer turnsratio. This voltage would be dangerously highto personnel and would damage the voltmeter.

Some important transformer installation rules arelisted below.

1. One or more transformers may be hung on asingle pole if the weight does not exceed the safe

Figure 4-14.—Standard connections for low-voltagedistribution transformers.

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strength of the pole or the crossarms and boltsas the barracks, is noted. Lines representing the servicesupporting them. leads are drawn between the pole and the building.

2. When more than one transformer is installed oncrossarms, the weight should be distributed equally onthe two sides of the pole.

3. Single-phase distribution transformers of 100kVA or smaller are usually placed above the secondarymains if conditions permit. Those larger than 100 kVAare usually platform or pad mounted.

Your next step is to determine the total connectedload of each service. It sounds complicated, but what itactually amounts to is summing up the power requiredby the lights and motors in each barracks. This powerdemand is noted in each square representing a barrack(fig. 4-15).

4. Lightning arresters and fused cutouts have to beinstalled on the primary side of all distributiontransformers except the self-protected type.

Next, figure out the kVA load per pole. In thisparticular example, each pole services two barracks;therefore, the kVA load of a pole will be the sum of thetotal connected loads of the two barracks served by thatpole.

5. Ground wires are required to be covered withplastic or wood molding to a point 8 feet above the baseof the pole.

What is involved in the determination of thetransformer size? Let’s suppose you are given the jobof installing a single-phase transformer in a certainarea of the base. This area contains 10 barracks thatreceive power from a 2,400-volt overhead primarymain. The electrical equipment in the barracks consistsof single-phase lights or motors operating at either110 or 220 volts. A three-wire overhead secondarymain distributes the secondary voltage alongside thebarracks. Service leads complete the connectionbetween the secondary main and each building.

Now, calculate the total maximum connected loadon the transformer. As you can see from figure 4-15,the total connected load is the sum of the kVA loads perpole. It amounts to 35.05 kVA. This amount of 35.05kVA represents the amount of power that thetransformer would have to supply if all the lights andmotors were consuming power at the same time.Although that possibility exists, the time intervalwould be small compared to the length of time thatonly a portion of the total load would be on. Therefore,it is necessary to calculate only the maximum demandload and then use this figure as a basis for determiningtransformer size.

The first thing you should do is make a roughdrawing of the area. When you are finished, it shouldlook like figure 4-15. The location of each pole, as well

An approximation of the maximum demand loadcan be computed by multiplying the total maximumconnected load by the demand factor listed in table 4-1.In this example, the maximum demand is 35.05 times

Figure 4-15.—Transformer size calculations.

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0.9 which equals 31.545 kVA. The transformercapacity to meet this demand will be 37.5 kVA. Thenext largest standard size transformer is 50 kVA, muchtoo large for this demand load, and the next smallersize is too small. However, if the computed totalmaximum load was 25.85 kVA times your demandfactor, this would give you 23.26 kVA; therefore, youwould need a 25 kVA transformer instead of the 37.5kVA transformer.

Your next problem is to determine the mostsuitable location for the transformer. That does notmean finding the strongest pole but finding the polethat is nearest to the electrical center of the area.

The electrical center is the point where a balance isobtained between the total kVA spans to the north andsouth of the location of the transformer. The kVA spanis the product of the number of spans times the kVAload of the pole.

To begin with, assume that you are going to placethe transformer on pole K (fig. 4-15). Then figure thetotal kVA spans to the north and south of this location.A chart will simplify your calculation.

kVA Spans North of kVA Spans South ofPole K Pole K

1 × 4.25 = 4.25 l × 9.1 = 9.1

2 × 1.3 = 2.6 2 × 14.2 = 28.46.85 37.5

Total kVA spans north Total kVA spans southof pole K = 6.85 of pole K = 37.5

You can see that if you placed the transformer onpole K, it would be at an imbalanced electrical center;that is, it would be too far away from the heaviest loads.So pick another pole. This time choose pole L andmake another chart.

kVA Spans North of kVA Spans South ofPole L Pole L

1 × 6.2 = 6.2 1 × 14.2 = 14.22 × 4.25 = 8.53 × 1.3 = 3.9 14.2

18.6 Total kVA spans southTotal kVA spans north of pole L = 14.2of pole L = 18.6

Pole L is nearest to the electrical center of the area.That is the pole on which you will mount the trans-former.

Table 4-1.—Demand Factor

Structure Demand Factor

Housing 0.9Aircraft maintenance facilities .7Operation facilities .8Administrative facilities .8Shops .7Warehouses .5Medical facilitiesTheatersNAV aidsLaundry, ice plants, and bakeriesAll others

.83.51.0.9

Single-phase distribution transformers aremanufactured with one or two primary bushings. Thesingle-primary-bushing transformers can be used onlyon grounded wye systems if they are properlyconnected. Figure 4-16 schematically shows theconnections of a single-phase transformer to a three-phase 2,400-volt three-wire ungrounded delta primaryvoltage system to obtain l20-volt single-phase two-wire secondary service. The connections for similarsystems operating at other primary distributionvoltages such as 4,800, 7,200. 13,200, and 34,400would be identical.

Figure 4-17 shows the proper connections for asingle-phase transformer to a three-phase three-wire

Figure 4-16.—Single-phase transformer connection for 120-volt two-wire secondary service. Transformer secondarycoils are connected in parallel.

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Figure 4-17.—Single-phase transformer connected to give120/240-volt three-wire single-phase service. Transformersecondary coils are connected in series.

ungrounded delta primary voltage system to obtain120/240-volt single-phase three-wire service.Normally the wire connected to the center low-voltagebushing will be connected to ground. Grounding thewire connecting to the center bushing limits thevoltage aboveground to 120 volts, even though thewires connecting to the outside secondary bushingshave 240 volts between them.

Figure 4-18 schematically shows the single-phasedistribution transformer connections to a three-phasefour-wire wye grounded neutral primary system rated4,160Y/2,400 volts to obtain 120/240-volt single-phase secondary service. The three-phase four-wirewye grounded neutral system has voltage betweenphases equal to the phase or line to neutral voltagemultiplied by 1.73. In figure 4-18, the primary system

line to neutral voltage is 2,400 volts, and the voltagebetween phases is 1.73 times 2,400, or 4,160 volts.This system is designated as a system. Other standard three-phase four-wire wyegrounded neutral primary system voltages are

a n d

The transformer connections to obtain 120,120/240-volt secondary service are normally completedinside the tank of the transformer (fig. 4-19). The

Figure 4-19.—Shows connections for 120/240-volt three-wire,240-volt three-wire, and 120-volt two-wire services.

Figure 4-18.—Single-phase transformer connected to provide 120/240-volt three-wire single-phase service. Primary winding isconnected to neutral or ground.

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transformer nameplate provides informationnecessary to complete connections. The voltagesshould be measured when the transformer is energizedto ensure that the connections are correct before theload is connected to the transformer.

Single-phase distribution transformers can beconnected to obtain three-phase secondary service(fig. 4-20). There are four normal connections: thedelta-delta (∆/∆). the wye-wye (Y/Y). the delta-wye (∆/Y), and the wye-delta (Y/∆). Figure 4-21 shows theproper connections for three single-phasedistribution transformers connected to a three-phasethree-wire ungrounded delta primary-voltage systemto obtain three-phase three-wire delta secondaryservice. The illustration is for a 2,400-volt primarysystem and voltages would be connected the same.Single-phase transformers with secondary windingsconstructed for voltage of 240/480 should be used toobtain 480-volt three-phase secondary service.

Figure 4-22 shows the proper connections for threesingle-phase distribution transformers connected to athree-phase four-wire grounded neutral wye primary-voltage system to obtain 208Y/l20- or 480Y/277-volt

Figure 4-20.—Cluster-mounted bank of transformers.

Figure 4-21.—Three single-phase distribution transformersconnected delta-delta.

Figure 4-22.—Three single-phase distribution transformersconnected wye-wye.

secondary service. Figure 4-23 shows the properconnections for three single-phase distributiontransformers connected to a three-phase three-wireungrounded neutral delta primary-voltage system toobtain 208Y/l20-or 480Y/277-volt secondary service.

Transformers must be constructed with the properwindings for the primary-voltage system and thedesired secondary voltage. Properly manufactureddistribution transformers can be connected wye-deltaif it is desired to obtain three-wire three-phasesecondary voltages from a three-phase four-wireground neutral wye primary-voltage system. The

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Figure 4-23.—Three single-phase distribution transformersconnected delta-wye.

standard secondary system three-phase voltages are208Y/120, 240, 480Y/277, and 480 volts.

If one of the transformers from a delta connectedbank is removed, the remaining two are said to be open-delta-connected. With one transformer removed, theremaining two transformers will still transform thevoltages in all three phases and supply power to all threephases of the secondary mains. The proper connections,using two transformers to obtain three-phase service,for a delta primary circuit are shown in figure 4-24. Thecapacity of the two transformers is now, however, only58 percent instead of 66 2/3 percent of what it wouldappear to be with two transformers.

The open-delta connection is often used where anincrease in load is anticipated. The third unit is addedwhen the load grows to the point at which it exceeds thecapacity of the two transformers. Furthermore, if onetransformer of the three-phase bank should becomedefective, the defective transformer can be removedand the remaining two transformers continue to renderservice to at least part of the load.

Capacitors

Power capacitors are used in distribution systemsto supply reactive voltamperes (Vars) to the system.When applied to a system or circuit having a laggingpower factor, you can obtain several beneficial results.These results include power factor increase, voltageincrease, system loss reduction, and an increase ofelectric system capacity.

POWER FACTOR.—When an alternatingvoltage and the current, which it causes to flow, rise

Figure 4-24.—Two single-phase transformers connectedopen-delta.

and fall in value together in the same direction at thesame instant, the two are said to be "in phase," and thepower factor is unity or 1.0. This condition is shown infigure 4-25.

The current and voltage waves are not in phase inmost cases. They do not rise and fall in value together,nor do they have the same direction at the same instant;but instead, the current usually lags behind the voltage.Figure 4-26 shows the usual condition in transmission

Figure 4-25.—Voltage and current waves are in phase;power factor is unity.

Figure 4-26.—Current wave lagging behind the voltage wave,usual condition in transmission and distribution systems.

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Table 4-2.—Power Factor of Various Types of Electrical Equipment

Equipment Power Factor Lagging/Leading

Incandescent lights 100% In phase

Heating devices (all types)

Induction motors (loaded)

Induction motors (light load)

100%

80%

20%

In phase

Lagging

Lagging

Neon lights

Synchronous motors (underexcited)

Synchronous motors (overexcited)

Static condensers

30-70%

Varies

Varies

0%

Lagging

Lagging

Leading

Leading

and distribution circuits. The current and voltage are have a strong tendency to lower the power factor. A lownow said to be "out of phase." The current drawn by system power factor can be increased by adding correctiveidle running induction motors, transformers, or equipment to the system. There are many devices used forunderexcited synchronous motors lags even more thanpower factor correction, including synchronous motorsthe current shown in the figure. and power factor correction capacitors.

Occasionally, the current leads the voltage. Anunloaded transmission line, an overexcited synchronousmotor or a static condenser takes leading current from theline. When the current leads or lags the voltage, the powerin the circuit is no longer equal to volts times amperes butis calculated from the expression:

SYNCHRONOUS MOTORS.—Any synchr-onous motor may be used for power factor correctionby overexcitation.

Watts = volts × amperes × power factor

Power factor = wattsvolts × amperes

P O W E R F A C T O R C O R R E C T I O NCAPACITORS. —For general use, the most practicaland economical power factor correction device is thecapacitor. Capacitors are used at power stations wherean elaborate and expensive synchronous condenserinstallation is not justified. The following paragraphsdeal exclusively with power capacitors.

The “power factor” can thus be defined as the ratioof the actual power to the product of volts timesamperes. The latter product is generally calledvoltamperes, or apparent power. The value of thepower factor depends on the amount the current leadsor lags behind its voltage. When the lead or lag is large,the power factor is small; and when the lead or lag iszero, as when the current and voltage are in phase, thepower factor is unity. Unity is the largest value that thepower factor can have. The power factor is usuallybetween 0.70 and 1.00 lagging. An average value oftenused in making calculations is 0.80 lagging. Table 4-2gives the power factors of various types of electricalequipment.

Capacitance is the direct opposite of inductance,just as heat is the opposite of cold, and day is oppositeof night. Capacitance is a property of a condenser, anda condenser is a combination of metal plates, or foilstrips, separated from each other by an insulator, suchas air, paper, or rubber. The capacitance, or thecapacity of the condenser to hold an electric charge, isproportional to the size of the plates and increases asthe distance between the plates decreases.

The cause of low power factor is an excessiveamount of inductive effect in the electric consumingdevice, be it motor, transformer, lifting magnet, and soforth. Induction motors, when lightly loaded, exhibit apronounced inductive effect. Idle transformers likewise

RATINGS. —Capacitors are rated in continuouskvar (kilovoltampere reactive), voltage, andfrequency. They are designed to give not less thanrated and not more than 135 percent rated kvar whenoperated at rated voltage and frequency. Capacitorunits are available normally in voltage ratings of 2,400volts to 34,500 volts and kvar ratings from 15 kvar to300 kvar. Various manufacturers’ medium-voltageunits up to 200 kvar are interchangeable. Capacitorsare generally rated at a frequency of 60 Hertz (Hz);

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however, they also are suitable for operation atfrequencies below 60 Hz. There is no physical limit tothe underfrequency operation of the capacitors. Thelimit is economic, in that the capacitor kvar output isdirectly proportional to frequency and applied voltage.If a capacitor is operated at a frequency lower thanrated, its kvar rating is reduced. Since capacitors areinstalled in theory to use their rated capacity,utilization at reduced frequencies is not economical, asthe design rating of the unit can never be achieved.

One method of raising the power factor is to addcapacitors to the circuit, since capacitance is theopposite of inductance and since too much inductanceis the cause of low power factor. Capacitors areinstalled underground on underground distributioncircuits or mounted on poles, as shown in figure 4-27.The pole-mounted three-phase bank capacitors shownin figure 4-27 are rated 1,200 kVA capacitance and13,200Y/7,620 volts; this bank is complete withswitches, fuses, and lightning arresters. The capacitorscan be directly connected to the circuit or switched on

Figure 4-27.—Cluster-mounted bank of 4 three-phasecapacitors.

and off as needed. An underground capacitor bank maybe equipped with oil switches for energizing three tosix capacitors. The capacitor equipment may beinstalled in a 36-inch diameter vault.

FIXED CAPACITORS. —Fixed capacitorinstallations are those that are continuously on the line.Fixed capacitor banks are connected to the systemthrough a disconnecting device that is capable ofinterrupting the capacitor current, allowing removal ofthe capacitors for maintenance purposes. Fixedcapacitor banks should be applied to give a voltageboost to the system during heavy load periods. Cautionmust be used, however, to ensure the boost will not beexcessive during light-load conditions. To isolate orde-energize a fixed capacitor installation, you shouldopen the disconnecting switches with rapid positiveaction. The successful switching of capacitorsdepends, to a considerable extent, on the technique ofthe operator and the speed of opening. It is moredifficult to de-energize a capacitor bank than it is toenergize it, because the ease with which capacitorcurrent is interrupted depends on the point on thevoltage wave when the switch contacts separate. If thearc is reestablished and maintained with thedisconnecting device open, the switch should bereclosed at once to avoid damage to the switch.Another attempt should then be made to open thedisconnecting device. After the disconnecting devicehas been opened, the capacitor installation is isolatedbut still charged. The capacitors should be left openfrom the line for at least 5 minutes before they arereturned to service. This precaution will prevent abuildup of the line voltage above normal, which mayoccur if a fully charged capacitor bank is closed on aline.

CAPACITOR CONNECTIONS. —A typicalthree-phase capacitor bank oil switch can be a three-pole device or three single-pole devices that can becontrolled automatically to switch the bank in or out ofservice to control the power factor or to regulatesystem voltage. Fuses provide short-circuit protection.If automatic switching is not required, the fuses can beused as load-break switches by using a portable load-break tool.

SWITCHED CAPACITORS. —Switchedcapacitor installations are those where the capacitorbank is switched in and out of service, depending uponsystem operating conditions. They are usuallyswitched on when the load requirements are thegreatest and switched off during light-load conditions.Sometimes the capacitor banks are installed to enable

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incremental switching, depending on the systemreactive requirements and the amount of systemvoltage required. To remove a switched capacitor bankfrom service, you should open the control box and theautomatic control lever. or control switch, should beplaced in the OFF position. The circuit breaker or theswitching device should then be tripped. To ensure thecircuit breaker or switching device remains open, youshould remove the fuses from the control circuit.Before it can be assumed that the capacitor bank hasbeen de-energized, the position of the switching deviceshould be inspected. On a circuit breaker, the positionindicator should be checked. For oil switches, theposition of the operating handle can be checked with aswitch stick.

CAPACITOR PRECAUTIONS. —Capacitorsand transformers are entirely different in theiroperation. When a transformer is disconnected fromthe line, it is electrically dead. Unlike the transformerand other devices, the capacitor is not deadimmediately after it is disconnected from the line. Ithas the peculiar property of holding its charge becauseit is essentially a device for storing electrical energy. Itcan hold this charge for a considerable length of time.There is a voltage difference across its terminals afterthe switch is opened.

Capacitors for use on electrical lines, however, areequipped with an internal-discharge resistor. Thisresistor. connected across the capacitor terminals, willgradually discharge the capacitor and reduce thevoltage across its terminals. After 5 minutes, thecapacitor should be discharged.

To be perfectly safe, however, proceed as follows:Before working on a disconnected capacitor, wait 5minutes. Then test the capacitor with a high-voltagetester rated for the circuit voltage. If the voltage is zero,short-circuit the terminals externally using hot-linetools and ground the terminals to the case. Now youcan proceed with the work.

COUPLING CAPACITORS. —Communicationsignals in the form of high-frequency voltages aretransmitted to the transmission lines through couplingcapacitors. Some of the coupling capacitors areequipped with potential devices that make it possibleto measure the voltage on transmission line circuits.The coupling-capacitor potential devices are accurateenough to be used for supplying voltage to protectiverelays but, unless they are specifically compensated,not accurate enough to supply voltage for metersdesigned for billing purposes. Figure 4-28 shows acoupling capacitor.

Figure 4-28.—Coupling capacitor.

TYPES OF SWITCHING DEVICES. —Switch-ing capacitors imposes severe duty on switchingdevices because of the differences in phaserelationship between the current and voltage on acapacitor circuit. When a capacitor bank is energized.high transient overvoltages and high-frequencytransient inrush currents may be produced. Themagnitude of the transient overvoltages easily may bethree times the rated line voltage, and transient inrushcurrents may approach the short-circuit current dutyvalues. These factors are especially important whenone or more capacitor banks already is energized andanother one at the same location is switched on to thebus. The methods for determining the values of inrushcurrent, transient overvoltage, and resonant frequencyof the circuit are discussed in more detail in ANSIC37.99. IEEE Guide for Protection of Shunt CapacitorBanks. and ANSI C37.012, Application Guide forCapacitance Current Switching of AC High- Voltage

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Circuit Breakers Rated on a Symmetrical CurrentBasis.

Switching devices, as discussed below, have aseparate capacitive switching rating for the reasonsmentioned above; and the switching rating of thedevice must be at least 135 percent of the capacitorbank rating to which the switching device is connected.This 135 percent rating is a minimum specified by theNational Electrical Code(NEC)® and includesallowance for operation at overvoltage, allowance forcapacitance manufacturing tolerance, and allowancefor harmonic components above the fundamentalfrequency.

CONSTRUCTION. —A capacitor unit consistsof two aluminum foil strips, or plates, with a thin high-grade insulating paper or a synthetic film placedbetween them. The strips, or plates, are compactlywound and connected in groups, each of which isconnected to a terminal. There is no contact betweenthe two metal surfaces. When these two surfaces areconnected to a source of power, energy is stored in thecapacitor. The capacitor remains charged at, or above:full-line voltage when disconnected from the source ofpower until a discharge path is provided between theterminals. Capacitors have a built-in discharge resistordesigned to drain off or reduce this residual charge.NEC® requires capacitors rated 600 volts or more to bedischarged to a residual voltage of 50 volts or less in 5minutes. Since the built-in resistor has thedisadvantage that it cannot be visually inspected for anopen circuit, it should not be relied upon for positivedrain off of the residual charge. The wound plates anddischarge resistor of a capacitor are enclosed in awelded sheet steel or stainless steel container, which ishermetically sealed to protect the capacitor fromdeterioration due to entrance of foreign material ormoisture. The contents are vacuum dried and areusually impregnated with a dielectric fluid. As of 1October 1977, dielectric fluids containingpolychlorinated biphenyls (PCBS) can no longer beinstalled. The connecting leads from the capacitor arebrought up through the bushings to a joint at the topdirectly under the brazed terminal. The bushingssupplied on capacitors are usually made of porcelain.As of 1 October 1988, existing PCB capacitors inunrestricted areas must be removed.

TYPES OF INSTALLATIONS. —The greatestelectrical benefits are derived from capacitorsconnected directly at the loads. This connectionpermits maximum loss reduction and released linecapacity. However,economics and physical

limitations are usually the governing factors.Capacitors may be divided into two classes: primarycapacitors and secondary capacitors. Primarycapacitors are those rated 2,400 volts and above.Secondary capacitors are those used on the low-voltage side of distribution transformers or at motorterminals and are normally rated 600 volts and below.The three most common types of power capacitorinstallation are as follows: pole mounted, metalenclosed, and open rack.

Pole Mounted.—Pole-mounted capacitors arepackaged as a complete unit containing all necessaryitems for a switched distribution capacitor bankinstallation. The banks consist of an aluminum- orsteel-mounting frame that supports the capacitor units,interconnecting wiring, and capacitor switches.Overcurrent, protection is usually provided by groupfuses.

Metal Enclosed.—Metal-enclosed capacitorbanks consist of a factory-assembled group ofindividual capacitor units mounted in a protectivehousing complete with bus connections, controls, andprotective and switching equipment within theenclosure. Personnel safety and compactness are themajor benefits. Each capacitor unit normally isprotected by an individual current-limiting fuse.

Open Rack.—An open-rack capacitor installation(fig. 4-29) is a field-assembled group of capacitor unitsmounted in an open-rack structure without enclosingplates or screens. Open-rack installations normally aremade up of several stack type of capacitors connectedin parallel to provide desired kvar capacity. All theunits in a given stacking unit are normally connected inparallel with the steel frame forming one terminal andthe insulated bus forming the other. For open-rackinstallations the capacitor units are protected byindividual fuses, group fuses or relays, and a circuitbreaker.

CAPACITOR MAINTENANCE. —Allswitched capacitor banks should be inspected andchecked for proper operation once each year before thetime period when they are automatically switched onand off to meet system requirements. A suggestedreading source for capacitor maintenance is TheLineman’s and Cableman’s Handbook.

Capacitor-bank oil switches should be maintainedon a schedule related with the type of on/off controlsinstalled at each bank. The maximum number of openand close operations between maintenance of theswitches normally should not exceed 2,500.

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Figure 4-29.—Capacitors, open-rack installation.

Experience has shown that the following schedulenormally will keep the equipment operating properly:

TYPE CONTROL YEARS

Time clock 3

Voltage 3

Dual temperature 5

Temperature only 8

Time clock and temperature 8

The capacitors switches usually are removed fromthe distribution line by the lineman and replaced with aspare unit during the season in which they normally arenot operated. The capacitor switches can bemaintained efficiently in a distribution shop by thelineman.

Protective/Interrupting Devices

A power distribution circuit, like any otherelectrical circuit, requires the use of special devices toprovide control and to protect the system from internalor external influences that may damage the circuit.Overcurrent/overvoltage protection and personnelsafety, requirements are provided in a power

distribution system by the use of lightning arresters,cutouts, fuses, air switches, and oil switches.

LIGHTNING OR SURGE ARRESTERS. —Asurge arrester is a device that prevents high voltages,by providing a low-impedance path to ground for thecurrent from lightning or transient voltages. and thenrestores normal circuit conditions.

Surge arresters perform a function on the electricsystem similar to that of a safety valve on a steamboiler. A safety valve on a boiler relieves high pressureby blowing off steam until the pressure is reduced tonormal. When the pressure is reduced to normal, thesafety valve closes and is ready for the next abnormalcondition. When a high voltage (greater than thenormal line voltage) exists on the line, the arresterimmediately furnishes a path to ground and thus limitsand drains off the excess voltage. Furthermore, whenthe excess voltage is relieved, the action of the arrestermust prevent any further flow of power current. Thefunction of a surge arrester is, therefore,twofold-first, to provide a point in the circuit at whichthe overvoltage impulse can pass to earth withoutinjury to line insulators, transformers, or otherconnected equipment and, second, to prevent anyfollow-up power current from flowing to ground.

DISTRIBUTION CUTOUT. —A distributioncutout provides a high-voltage mounting for the fuseelement to protect the distribution system or theequipment connected to the system (fig. 4-30).Distribution cutouts are used with installations of

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Figure 4-30.—Mounted distribution cutout with expulsionfuse.

Figure 4-31.—Distribution cutouts installed for transformerbank switching.

transformers, capacitors, cable circuits, andsectionalizing points on overhead circuits (fig. 4-31).Enclosed, open, and open-link cutouts are used fordifferent distribution circuit applications. Cutoutsnormally use an expulsion fuse. An expulsion fuseoperates to isolate a fault or overload from a circuit.The arc from the fault current erodes the fuse holdertube producing a gas that blasts the arc out through thefuse tube vent(s) thereby isolating the circuit.

The mechanical differences between enclosed,open, and open-link cutouts are in their externalappearance and methods of operation. Enclosedcutouts have terminals, fuse clips, and fuse holdersmounted completely within an insulating enclosure.Open cutouts, as the name indicates, have these partscompletely exposed.

The construction of the cutout fuse holder can pro-vide for non-dropout or dropout operation. Some of thefuses are manufactured to provide indication that thefuse is blown; other fuses may have an expendable cap.

ENCLOSED DISTRIBUTION CUTOUT. —Inan enclosed distribution fuse cutout the fuse clips andfuse holder are mounted completely within anenclosure. A typical enclosed cutout, as shown infigure 4-32, has a porcelain housing and a hinged doorsupporting the fuse holder. The fuse holder is a hollowvulcanized-fiber expulsion tube. The fuse link isplaced inside the tube and connects with the upper andlower line terminals when the door is closed. When the

Figure 4-32.—Enclosed primary cutout assembly.

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fuse blows or melts because of excessive currentpassing through it, the resultant arc attacks the walls ofthe fiber tube, producing a gas which blows out the arc.The melting of the fusible element of some cutoutscauses the door to drop open, signaling to the linemanthat the fuse has blown.

Each time the fuse blows, a small amount of thevulcanized fiber of the expulsion tube is eroded away.The larger the value of the current interrupted, themore material is consumed. In general, a hundred ormore operations of average current values can beperformed successfully before the cutout fails.

Enclosed cutouts can be arranged to indicate whenthe fuse link has blown by dropping the fuse holder.The enclosed cutout is designed and manufactured foroperation on distribution circuits of 7,200 volts andbelow. The standard current ratings of the cutouts are50, 100, or 200 amps.

OPEN DISTRIBUTION CUTOUT. —Opentypes of cutouts are similar to the enclosed typesexcept that the housing is omitted (fig. 4-33). The opentype of cutout is designed and manufactured for alldistribution system voltages. The open type is made for100- or 200-amp operation. Some cutouts can beuprated from 100 to 200 amps by using a fuse tuberated for 200-amp operation.

PRIMARY FUSE LINKS. —A primary fuse linkconsists of the button, upper terminal. fusible element,lower terminal, leader, and sheath. The button is theupper terminal and the leader is the lower terminal.Fuse links for open-link cutouts are similar to theprimary fuse link except that open-link cutouts havepull rings at each end. In either case, the sheath aids inthe interruption of low-value faults, and it providesprotection against damage during handling.

Figure 4-33.—Open-distribution cutout.

Standards specify the size of the fuse holder intowhich the link must fit freely. Links rated 1 to 50 ampsmust fit into a 5/16-inch diameter holder, 60- to 100-amp links must fit into a 7/17-inch diameter holder,and 125to 200-amp links must fit into a 3/4-inchdiameter holder. Links must withstand a 10-pound pullwhile carrying no load current but are generally given a25-pound test.

Fusible elements are made in a wide variety ofdesigns. Most silver-element fuse links use thehelically coiled construction. This constructionpermits the fusible element to absorb vibration as wellas thermal shock due to current surges and heating andcooling throughout the daily load cycle.

FUSE LINK OPERATION. —When a faultoccurs, the fusible element is melted by the excessivecurrent, and an arc forms across the open gap. The arcis sustained temporarily in a conducting path ofgaseous ionized arc products. Gas pressure buildsrapidly; and this pressure, acting in conjunction with aspring-loaded flipper at the lower end of the fuse tube,rapidly ejects the fuse link leader, lengthening andcooling the arc. For low values of fault current, the arcacts on the fuse link sheath, generating considerableamounts of deionizing gases. When the current passesthrough the next zero value, as it changes the directionof flow, the arc is interrupted (fig. 4-34). As the voltageincreases again across the opening in the fuse link, thearc attempts to reestablish itself. A restrike, however,is prevented by the deionizing gases which will haverebuilt the dielectric strength of the open gap. For largevalues of fault current, the sheath is rapidly destroyed,and the arc erodes fiber from the inner wall of thecutout tube. generating large amounts of deionizinggas. During the fault interruption process, the cutoutexpels large amounts of gas under high pressure as well

Figure 4-34.—Diagram of voltages, current, and timingreference recorded with an oscillograph to show fuseoperation.

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as some fuse link particles. There also may be a veryloud report. Accordingly, when one is working in thevicinity of a fuse cutout, care should be taken to stayclear of the exhaust path. In addition, when closing acutout, it is good practice to look down, away from thedischarge path, since there is always the possibility ofclosing the cutout into a short circuit.

RECOMMENDED SIZE OF PRIMARYFUSE.—Table 4-3 gives the recommended size ofprimary fuses to use with different transformer voltage andkilovoltampere ratings. The table also gives the normalfull-load primary current rating of the transformer.

It is general practice not to protect distributiontransformers against small overloads. To do so wouldcause unnecessary blowing of the fuses and frequentinterruption of the service, both of which areundesirable. It is customary, therefore, to provide fuseswhich have a higher current rating than the currentrating of the transformer.

AIR SWITCHES. —As their names imply, airswitches are switches whose contacts are opened in air.

Air switches are further classified as air circuitbreakers, air-break switches, and disconnects.

Circuit Breaker. —A device used to complete,maintain, and interrupt currents flowing in a circuitunder normal or faulted conditions is called a circuitbreaker. The circuit breaker has a mechanism thatmechanically, hydraulically, or pneumaticallyoperates the circuit breaker contacts. Insulating oil, air,compressed air, vacuum, or sulfur hexafluoride gas isused as an arc-interrupting medium and a dielectric toinsulate the contacts after the arc is interrupted. If thecircuit is to open automatically during overload orshort circuit conditions, the circuit breaker is equippedwith a tripping mechanism to accomplish this. Thus,circuit breakers normally are used where control of thecircuit, as well as protection from overload, shortcircuit, and so forth is desired, such as at generatingstations and substations.

Air-Break Switch.—The air-break switch canhave both blade and stationary contacts equipped witharcing horns. These horns are pieces of metal betweenwhich the arc forms when a current-carrying circuit isopened. As the switch opens, these horns are spread

Table 4-3.—Fuse Size for Transformer Installations

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farther and farther apart, thereby lengthening the arcuntil it finally breaks.

Air-break switches are usually mounted onsubstation structures or on poles and are operated fromthe ground level (fig. 4-35). In a three-phase circuit allthree switches. one in each phase. are opened andclosed together as a “gang,” as the system is called. Theswitches can be operated by a handle connected to therod extending from the switch to the base of the pole.Remember, the opening of a three-phase gang switch isa two lineman project. One lineman opens the switch;the other lineman is for safety—he watches to ensurethat all phases open. Many of the air rods extendingfrom the air-break switches are operated bymechanized equipment connected to the switch-operating rod from a remote location. The automationofdistribution circuits has resulted in the installation ofmany mechanized operators for key break switches sothat they can be controlled from a central operationscenter. Switches for underground distribution circuitsusually are installed in pad-mounted switchgear. Theswitches are operated with the cabinet doors closed toprovide protection for the lineman or cableman.

Disconnect Switch.—A disconnect switch is anair-break switch not equipped with arcing horns orother load-break devices. The disconnect switchcannot be opened until the circuit in which it isconnected is interrupted by. some other means, such asa portable load break tool attached to a hot-line tool. Ifa disconnect switch is opened while current is flowingin the line. an arc is likely to be drawn between theblade and the stationary contact where the arc mighteasily, jump across to the other conductor or to somegrounded metal and cause a short circuit. The hot arcalso could melt part of the metal. thereby, damagingthe switch.

Figure 1-35.—Gang-operated three-pole air-break switch witharc interrupters (in the open position).

Disconnect switches are used to complete aconnection to or isolate the following:

1.

2.

3.

4.

Two energized transmission or distributionlines

Transmission or distribution lines fromsubstation equipment

Substation equipment

A distribution feeder circuit and a branchcircuit

Disconnect switches are frequently used to isolatea line or an apparatus, such as a transformer. tocomplete maintenance work. In most circumstances, itis necessary to test the equipment for high voltage and,if proved de-energized, to ground it before themaintenance work is performed.

OIL SWITCH. —An oil switch is a high-voltageswitch whose contacts are opened and closed in oil.The switch is actually immersed in an oil bath andcontained in a steel tank. The reason for placing high-voltage switches in oil is that the oil will break thecircuit when the switch is opened. With high voltages.a separation of the switch contacts does not alwaysbreak the current flow because an electric arc formsbetween the contacts. If the contacts are opened in oil.the oil will quench the arc. Furthermore. if an arcshould form in the oil. it will evaporate part of the oilbecause of the high temperature and will partially fillthe interrupters surrounding the switch contacts withvaporized oil. This vapor develops a pressure in theinterrupters which assists in quenching or breaking thearc by elongating the arc.

The three lines of a three-phase circuit can beopened and closed by a single oil switch. If the voltageis not extremely high. the three poles of the switch aregenerally in the same tank (fig. 3-36): but if the voltageof the line is high. the three poles of the switch areplaced in separate oil tanks. The poles are placed inseparate tanks to make it impossible for an arc to formbetween any two phases when the switch is opened orclosed. An arc between phases would be a short circuitacross the line and would probably blow up the tank.

When an oil switch is to open the circuitautomatically because of an overload or short circuit. itis provided with a trip coil. This trip coil consists of acoil of wire and a movable plunger. In low-voltagecircuits carrying small currents. this coil is connectedin series with the line. When the current exceeds itspermissible value. the coil pulls up its plunger. Theplunger trips the mechanism, and a spring opens theswitch suddenly.

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Figure 4-36.—Three-phase oil switch recloser.

In high-voltage circuits or in circuits carryinglarge currents, a current transformer is connected intothe line and the secondary leads from this transformersupply the current to the trip coil of the oil switch (fig.4-37). Since there is a fixed ratio between primary andsecondary currents of the current transformer, the coilcan be adjusted to trip at any predetermined value ofcurrent in the line.

The use of the current transformer on such circuitsserves the dual purpose of providing a small current foroperating the tripping coil and insulating the coil fromthe high voltage of the line.

Figure 4-37.—Current transformer used to supply current tothe trip coil of an oil switch.

An oil circuit recloser is a type of oil switchdesigned to automatically interrupt and reclose analternating-current circuit. It can be made to repeat thiscycle several times. Reclosers are designed for use onsingle-phase circuits or on three-phase circuits.

A recloser opens the circuit in case of fault aswould a fuse or circuit breaker. The recloser, however,recloses the circuit after a predetermined time (forhydraulically controlled reclosers about 2 seconds). Ifthe fault persists, the recloser operates a predeterminednumber of times (1 to 4) and “locks out,” after which itmust be manually reset before it can be closed again. If,however, the fault was of a temporary nature andcleared before lockout, the recloser would reset itselfand be ready for another full sequence of operations.

Temporary faults arise from wires swingingtogether when improperly sagged, from tree branchesfalling into the line, from lightning surges causingtemporary flashover of line insulators, and fromanimals on the conductors short circuiting theinsulators.

A recloser is unlike a fuse link because itdistinguishes a temporary from a permanent fault. Afuse link interrupts temporary and permanent faultsalike. Reclosers give temporary faults repeatedchances, usually four, to clear or be cleared by asubordinate device, like a fuse or sectionalizer. If thefault is not cleared after four operations, the recloserrecognizes it as a permanent fault and operates to lockout and leave the line open.

A recloser can be magnetically operated by asolenoid connected in series with the line. Minimumtrip current is usually twice the normal load currentrating of the recloser coil. The operations areperformed by a hydraulic mechanism and amechanical linkage system. When the fault currentreaches twice the normal line current, the increasedmagnetic field pulls the plunger down into the coil. Asthe plunger moves downward, the lower end trips thecontact assembly to open the contacts and break thecircuit. As soon as the contacts are open, there is nomore current in the coil to hold them open, so a springcloses the mechanism and reenergizes the line.

PROTECTIVE GROUNDS

Protection to the lineman is most important when atransmission or distribution line or a portion of a line isremoved from service to be worked on using de-energized procedures. Precautions must be taken to besure the line is de-energized before the work is started

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and remains de-energized until the work is completed.The same precautions apply to new lines whenconstruction has progressed to the point where theycan be energized from any source.

The installation of protective grounds and short-circuiting leads at the work site protects against thehazards of static charges on the line, induced voltage,and accidental energizing of the line.

When a de-energized line and an energized lineparallel each other, the de-energized line may pick up astatic charge from the energized line because ofproximity of the lines. The amount of this static voltage“picked up” on the de-energized line depends on thelength of the parallel, weather conditions, and manyother variable factors. However, it could be hazardous;and precautions must be taken to protect against it bygrounding the line at the location where the work is tobe completed. Grounding will drain any static voltageand protect the workman from this potential hazard.

When a de-energized line parallels an energizedline-carrying load. the de-energized line may have avoltage induced on it in the same manner as thesecondary of a transformer. If the de-energized line isgrounded at a location remote from where the work isbeing done, this induced voltage will be present at thework location. Grounding the line at the work locationwill eliminate danger from induced voltage.

Grounding and short circuiting protect against thehazard of the line becoming energized from eitheraccidental closing ofthe line or accidental contact withan energized line that crosses or is adjacent to the de-energized line.

The procedures established to control theoperation of equipment in an electrical systempractically prevent the accidental energizing of atransmission or distribution line. Hold-off taggingprocedures have proven to be very effective. If acircuit should be inadvertently energized, thegrounds and short circuits on the line will cause theprotective relays to initiate tripping of the circuitbreaker at the source end of the energized line in afraction of a second and de-energize the hot line.During this short interval of time, the grounds andshort circuits on the line being worked on will protectthe workmen (fig. 4-38). If it is not grounded, it is notdead!

Figure 4-38.—Grounding cluster installation.

UNDERGROUND CONSIDERATIONS

Electric distribution circuits have been installedunderground for many years. The conventionalunderground systems employ the use of some, if notall, of the following: conduits encased in concrete,manholes, ducts and trenches, direct burial cable andriser/potheads, underground power cables, andunderground communication cables. After it has beendetermined that the load density is high enough tojustify the expenses associated with an undergroundsystem, the system must be designed; and thenconstruction may begin.

MANHOLES

Manholes, handholes, and vaults will be designedto sustain all expected loads that may be imposed onthe structure. The horizontal or vertical design loadswill consist of dead load, live load, equipment load,impact, load due to water table or frost, and any otherload expected to be imposed on or occur adjacent to the

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structure. The structure should sustain the combinationof vertical and lateral loading that produces themaximum shear and bending moments in the structure.

Manholes are necessary in a power distributionsystem to permit the installation, removal, splicing,and rearrangement of the cables. A manhole is merelya subterranean vault or masonry chamber of sufficientsize to permit proper manipulation of the cables.Arranged on the sides of the vault are devices thatsupport the cables.

The location of manholes is determined largely bythe layout of the base that is to be supplied with power.Whenever a branch or lateral extends from the mainsubway, there must be a manhole; and there must bemanholes at intersections of subways. In general,cables are not made in lengths exceeding 400 to 600feet; and as it is necessary to locate splices inmanholes, the distance between manholes cannotexceed these values. Furthermore, it is not advisable topull in long lengths of cable because the mechanicalstrain on the conductors and sheath may then becometoo great during the pulling-in process. It isrecommended that manholes be located not more than500 feet apart. The lines should preferably be runstraight between manholes.

Manholes are made in many shapes and sizes tomeet the ideas of the designer and to satisfy localconditions. An example of a typical manhole is shownin figure 4-39. If there are obstacles at the point where amanhole is to be located, the form of the manhole mustbe modified to avoid them. The form approximating anellipse (fig. 4-40) is used so that the cables will not beabruptly bent in turning them around in the manhole.When the rectangular type of manhole is used (fig.4-41), care must be taken not to bend the cables toosharply.

The size of a manhole will vary with thenumber of cables to be accommodated; but, in anycase, there must be sufficient room to work in themanhole. A 5- by 7-foot manhole is probably as largeas will be required in isolated plant work, while a 3- by4-foot manhole is about as small as should be used.When transformers are located in a manhole, the sizeshould be increased to allow for working space aroundthe transformer and for ventilation. About 2 or 3 feet ofvolume should be allowed per kilovoltampere oftransformer rating.

Manholes are built of either brick or concrete or ofboth of these materials. When many manholes are to bebuilt of one size and there are no subterranean

obstructions, concrete is usually the cheapest and thebest material. But when only a few are to beconstructed or when there are many obstructions, amanhole with a concrete bottom, brick sides, and aconcrete top is probably the best. Such a manhole canbe constructed without having to wait for concrete toset before you can remove the forms. There is agrowing use of precast concrete manholes that areshipped directly to the project site.

A manhole with brick walls is built by first pouringthe concrete floor and then building up the brick wallsthereon. If the manhole is large, the roof can be eitherof steel-reinforced concrete or of brick set betweenrails. Probably for installations in which only a fewmanholes are to be built, the brick-between-railsmethod is the best. For a small manhole, no masonryroof is necessary, as the cast-steel manhole coverforms the roof.

Cement mortar for building brick manholes or forconduit construction can be made by mixing together 1part of cement, 3 parts of sand, and about 1/3 part ofwater, all by volume.

A concrete manhole is built by first pouring theconcrete floor and then erecting the form for the sides.In a self-supporting soil, the sides ofthe hole constitutethe form for the outside of the manhole. If the soil is notself-supporting, there must be an outer form of roughplanks (plywood), which is usually left in the ground.Steel reinforcing, such as old rails, must be placed inthe concrete top of a large manhole. All reinforcingsteel should be completely encased in concrete toprevent corrosion.

Manhole covers should always be made of caststeel and covers should be round so that they cannotdrop into the hole accidentally.

So-called watertight covers are seldom used now,as it is not feasible to make a satisfactory watertightcover at reasonable expense. A cover should not befastened down because if it is and accumulated gas in amanhole explodes, the vault and cover will beshattered. A ventilated cover should be used to allowthe escape of gas. The newer types have ventilatingslots over approximately 50 percent of their area. Dirtand water will get into the hole, but the dirt can becleaned out and the water will drain out and no harmwill result. If ventilation is not provided, an explosionof gas may occur and do great damage.

When feasible, a sewer connection should leadfrom the bottom of every manhole. The mouth of thetrap should be protected by a strainer made of

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Figure 4-39.—Typical manholes.

noncorrosive wire. If a sewer connection cannot bemade, there should be a hole in the manhole floor sothat water can drain out. A pocket under the manholefilled with broken rock will promote effectivedrainage.

WARNING

Before entering any manhole, the vault mustbe ventilated to remove all toxic or explosivegases and ensure adequate oxygen forsurvival. Forced air ventilation, respiratory

Figure 4-40.—Elliptical type of manhole. Figure 4-41.—Rectangular type of manhole.

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protection, an observer on the surface, and asafety harness and line may be required forsafe entry. Consult your supervisor beforeentering any manhole.

DUCTS AND TRENCHES

A duct line and manhole system provide the bestavailable underground system. Such a system allowsfor growth and permits cost-effective replacement ofexisting cables or cable terminations damaged byfaults or made obsolete by aging. Concrete encasementprovides the cables with minimum susceptibility todamage and optimum safety to personnel. Severaltypes of underground ducts are in general use, such asfiber, wood, vitrified tile, iron pipe, asbestoscomposition polyvinyl chloride (PVC). and concrete.The most common type used today by the Navy isPVC.

An underground installation usually consists ofseveral duct lines. Joints between sections should bestaggered, so the joints in several lines do not all occurat the same place. To ensure staggering, use startingsections of different lengths at the starting manhole.For duct set in concrete, there must be at least 3 inchesof concrete around each line of duct. Where concreteencasement is specified, concrete should have astrength of not less than 2,500 pounds per square inchwhen cured for 28 days. The 3-inch spacing isaccomplished by the use of spacers, like the one shownin figure 4-42. The upper lines of the duct must be aminimum of 3 feet below the ground surface.

The location of the trench varies according toground condition. The trench should run as straight aspossible from one manhole to the next. To ensuredrainage, slope the line downward about 1 foot butnever less than 3 inches every 100 horizontal feet.When one manhole cannot be located at a lower levelthan the other, the tine must slope downward fromabout the midpoint both ways toward the manhole, asshown in figure 4-43.

Dig the trench to the desired depth and tamp thebottom hard to ensure a solid bed for the 3-inch bottomlayer of concrete. Spacers can be embedded in thebottom layer of concrete for a depth of about 1 inchbefore the concrete sets to ensure a solid base.

Burying cable directly in the ground is widelydone for installations of single circuits for which thecost of duct construction would be prohibitive. Someof the more common applications of direct burial cableare as follows:

1. Street-lighting circuits, especially on a basewhose outlying sections are without ducts

Figure 4-42.—Spacing fiber duct in concrete. 2. Connecting residences to mains

Figure 4-43.—Slope for duct run.

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3. Railroad yards, railway-signal circuits andairport lighting

3. Lighting and power circuits for amusementparks, baseball and football fields, andindustrial plants

5. Crossing under small lakes and streams

Both nonmetallic-armored cable and metallic-armored cable (parkway cable) are used for directburial in the earth. The nonmetallic-armored types arelighter in weight. more flexible, and easier to spliceand are not subject to rust, crystallization, inducedsheath power loss, or trouble from stray currents. Onthe other hand, they do not give good protectionagainst mechanical injury,.

Direct burial of power cable is normallyaccomplished with a backhoe digging a trench largeenough to permit bed preparation. Whereascommunications cable is laid in a small trench createdby a chain type of mechanical trencher. Cables areinstalled at a minimum depth of 30 inches for powercables of 600 Vac or over and 18 inches forcommunications cables. Cables installed at 30 inchesor greater will be protected against extrememechanical hazard, such as at street intersections orunder roadways. The powercables should be placed ina 3-inch-thick bed of sand. When backfilling a directburial cable. you should place plastic streamers in thetrench 12 to 18 inches above the cable. These streamerswill alert future personnel conducting diggingoperations to the presence of the buried cable.

At intervals of 200 feet and at turns in the buriedcable, you also should place small-concrete markersalong the entire length. These precautionary signsshould prevent some future human-related damages tothe buried distribution systems. The marker shouldstate the type of cable that is buried, such as power orcommunications, and voltage or number of pairs.

Types UF and USE cables are code-designatedsingle-conductor or multiconductor cables suitable fordirect burial in the earth. The NEC® includes rules forthe protection of underground conductors when thesupply voltage exceeds 600 volts. These rules wereintroduced to minimize the hazards of “dig-ins.”Section 710-3(b) of the NEC® covers such rules.

RISERS/POTHEADS

For connection of underground distributioncircuits at any location. the end must be prepared fortermination. In earlier times this preparation wasaccomplished with a pothead. as shown in figure 4-44,

Figure 4-44.—Pothead.

but is now done with special kits which provideplastic molds to be placed over individually preparedphases. The molds are poured full of epoxy. The newway is much more efficient and clean. The new styleis shown in figure 4-45.

The riser pole for underground distributioncircuits should be inspected when overhead lines areinspected and maintained (fig. 4-46). The inspectionshould include the disconnect switches or fusedcutouts, the lightning arresters, the operation of thearrester ground leads isolation devices, the riser cablesand potheads or termination, support of the cables,conduit or U-guard, and identification of the circuitand pole conditions.

Figure 4-45.—Diagram of a modern single-phase cable endtermination kit.

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Figure 4-46.—Riser pole for underground distribution circuit.

UNDERGROUND POWER CABLES

Underground cables have various types ofinsulation and sheaths. Because higher voltagesgenerate more heat, the amount of voltage carrieddetermines the composition of the insulation.

Cables rated at 15 kilovolts and below usuallyhave rubber or varnished cambric insulation and aPVC or rubber sheath. Those rated at 600 volts to 425kilovolts have oil-impregnated paper insulation and aPVC sheath.

Cables rated at 5 kilovolts and above have metallictape shields between the insulation and sheath formechanical protection. Exceptions to this requirementare for single-conductor (1/0) cable with a PVC sheathand three-conductor (3/0) belted type of cable.

Much of the new cable being installed is cross-linked-polyethylene (XLP) or ethylenepropylenerubber (EPR). These are called solid type ofinsulations. The size and number of conductors in thecable depend on the job requirements.

UNDERGROUND COMMUNICATIONSCABLES

The most common types of undergroundcommunications cables in use today are steel-armoredwith plastic insulation (STELPATH), plastic-insulated with aluminum armor (PIC), and the newshielded fiber-optic cables.

PULLING CABLE

When installing a new run of duct, you pull in“pulling wire,” usually a lo-gauge iron wire. With thiswire, you pull in a wire rope to which you attach thecable for pulling in.

Sometimes, when the duct has been in the ground along time, the original iron pulling wire may be rustedso that it is not strong enough to pull the wire ropethrough. Also for a 400- to 500-foot run, it would bedifficult to push a fish tape through the duct. The jobcan be simplified by using an air compressor to blow achalk line cord through the duct. To do this, take asmall cloth and tie the chalk line end to the fourcomers, so the cloth functions like a small parachute.

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With the air hose in the end ofthe duct and the cord freeto run out, you will be able to blow the cloth through tothe next opening, even on a long run of duct.

Cleaning ducts is accomplished by rodding.Quick-coupling duct rods (about 1 feet long and 1 inchin diameter) are connected together with a wire brushor other duct rod leader at the head to facilitatecleaning. The rods may be pushed through manually orby means of power equipment. A 12-gauge galvanizedsteel wire attached to the leader is left in the duct for thecable pulling crew.

Moisture inside a cable causes deterioration of theinsulation; therefore. precautionary measures shouldbe taken to avoid the accumulation of moisture insidethe cables. Before pulling a cable. ensure that the cableends are sealed against moisture invasion.

RIGGING

Figure 4-47 shows a number of ways to rigmanholes for cable pulling. View A shows the cablepulley attached to a timber block which, in turn, issupported by a wedge. In view B, the pulley is shownattached to the manhole wall by means of an embeddedeye. If you use this method. make sure that the lowersheave is in line and level with the duct in which thecable is to be pulled. To prevent injury, to the cable bysharp edges. line the duct mouth with a shield.

Either of the above methods will probably besatisfactory for most of the jobs you will handle.Sometimes. however. more complex rigging is calledfor, especially in cases when the cable requires heavypulling. For jobs of this nature, you will find the otherviews in figure 4-47 helpful.

When pulling cables into a long duct. use a feedingtube or bell for applying a lubricant at the duct mouth.Make sure you use the lubricant specified by themanufacturer of the cable.

Make a plank runway to support the reel formovement over areas where dirt, cinders, or crushedstone might damage the cable. All cable reels aremarked with an arrow. indicating the direction inwhich they must be rolled. Comply with this arrowwhen placing the reel at a manhole so that it turns inthe proper direction as cable is pulled from the reel.Place the reel as near as practical to the manhole andraise it on reel jacks just enough to clear the ground.Figure 4-48 shows a reel in proper position over themanhole so that the bend in the cable is not reversed asthe cable is unreeled. Notice the scuff boot at the edge

Figure 4-47.—Manhole rigging for pulling cables.

Figure 4-48.—Reel in proper position.

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of the manhole to prevent damage to the cable sheath.A section of an old tire casing can serve as a protectiveboot for this job.

The boards nailed to the two edges of the reel arecalled lagging. When the reel is in place, remove thelagging. You must be careful not to damage the cablewhen you pry the lagging loose. Be sure to remove anyprojecting nails from the edge of the reel beforestarting to remove the cable. Next, you must release theend of the cable from the reel, and you will then beready for the main part of the job.

CABLE INSTALLATION

Assume that the winch line has been drawn into theduct, as the test line was pulled out. A basket grip isnow attached to the end of the underground cable onthe reel. The end of the basket is secured to the cablewith a tight wrap of tape or wire. A swivel connectionis necessary between the basket and the pulling cableto relieve twisting of the rope.

If the cable reel is within sight of the winch, it willtake four people, in addition to the winch operator, todo the job safely. One person attends the reel to see thatthe cable rolls off the reel properly. Another in themanhole guides the cable into the duct. Both inspectthe cable as it unreels and immediately signal “stoppulling” when a defect appears so that a closerinspection can be made for possible damage to thesheath. A third, stationed in the other manhole at thepulling end. signals “stop pulling” when the cableappears. The fourth crew member, aboveground at thepulling-end manhole, relays signals to the winchoperator. This procedure enables the winch operator toconcentrate on his job of seeing that the winch line iswound onto the reel properly.

The speed for pulling cable into a duct varies withthe length of the duct and cable sizes. A single cablecan be pulled in successfully at 75 feet per minute in aclear. straight duct. When you are handling more thanone cable, reduce the speed to about 20 to 25 feet perminute, so you can prevent the conductors fromcrossing as they enter the duct.

When the “stop pulling” signal is given, make surethere is sufficient slack in both manholes for splicingor terminating the cable. The slack can be adjustedwith the cable basket grip. Exercise care to preventinjury to the cable insulation. Remove the binding tapeand the basket grip from the cable. The cable is then cutto the desired length and the cutoff end in the manholeis sealed unless splicing is done immediately. The end

of the cable remaining on the reel also must be sealed.In addition, check the seal on the end of the cable thathas traveled through the duct, and reseal it if it has beenbroken from the strain.

DANGEROUS GASES

Gases may be dangerous for several reasons. Thegas concentration may be explosive if it is made up ofmethane, sewer gas, natural gas, concentrations ofspilled gasoline, or other liquid fuel vapors. As ageneral rule, these gases are heavier than air and willconcentrate in low areas, such as manholes and ducts.They will remain there until they are dispersed. Thesegases are toxic as well as explosive. Other toxic gasesare chlorine, ammonia, and a variety of the sulfidecombinations. Other gases deplete the oxygen in themanholes and duct systems. Lack of oxygen can be asdeadly as either the explosives or toxic gases. For thesereasons, underground structures must be tested beforeworkers enter them. Figure 4-49 shows two commontypes of test sets used for identifying carbon monoxideand combustible gases. View A shows a carbonmonoxide tester and view B, an explosimeter. Onlypersonnel who are specifically trained and certifiedmay conduct tests for safe entry. Before entering anyunderground structures the base confined spacemanager or the assistant must certify the area safe forentry.

MAINTENANCE

Test equipment is essential for satisfactory powersystem operation. Meters are needed to monitorsystem operation conditions and also to checkequipment before and after placing it in service.Periodic checks are necessary to ensure that theequipment remains in proper operating condition.

BASIC MEASURING INSTRUMENTPRECAUTIONS

When using measuring instruments, you mustobserve certain precautions. For example, it isespecially important to be careful in using an ammeterbecause of its low internal resistance. If mistakenlyplaced across a voltage source, the meter can bedamaged. Always break the circuit and CONNECTAN AMMETER IN SERIES with one meter lead goingto each point of the circuit breaker to measure anunknown quantity. Be sure to de-energize the circuitbefore making or breaking the connections.

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Figure 4-49.—Underground gas-testing apparatus.

When using either ammeters or voltmeters:ALWAYS start at the HIGHEST meter range. Thendrop down to a lower scale range if necessary. Thispractice protects the meter from injury if an attempt ismade to read a high value in a low range. Damage toinstruments also can be minimized if you form a habit

of placing the range selector switch in the highestrange position after you have finished using theinstrument.

OBSERVE POLARITY on all direct-currentmeasurements. Take care to connect the positiveterminal of the source to the positive terminal of themeter and the negative terminal of the source to thenegative terminal ofthe meter. This action ensures thatthe meter polarity matches the polarity of the circuit inwhich the meter is placed.

Be careful to avoid dropping a meter or subjectingit to excessive mechanical shock. Such treatment maydamage the delicate mechanism or cause thepermanent magnet to lose some of its magnetism.

Care must be taken to avoid connecting theohmmeter across circuits in which a voltage exists,since such connection can result in damage to theinstrument. TO ENSURE THE REMOVAL OF ALLVOLTAGE TO THE EQUIPMENT UNDER TEST,DISCONNECT THE SOURCE OF THE INPUTVOLTAGE BY REMOVING THE POWER PLUG.Furthermore, ALL CAPACITORS MUST BEDISCHARGED before the ohmmeter prods areconnected in the circuit. Charges remaining oncapacitors after the applied voltage has been removedcan severely damage the instrument.

Always turn ohmmeters OFF when finished. Thisaction will avoid discharge of the internal battery if thetest leads are shorted inadvertently.

It is important that you remember to USE A LOW-VOLTAGE MEGGER TO TEST LOW-VOLTAGEINSULATION. Application of high voltage mayinitiate insulation breakdown. low-voltage meggersshould not be used to test high-voltage insulationbecause an inaccurate reading may result from thecomparatively small output voltages available fromthis instrument. Be careful whether using high or lowrange meggers. Dangerous voltages exist at meterterminals and leads.

DIGITAL MULTIMETERS

There are a lot of different types and styles ofautoranging digital multimeters that are designed forthe professional at work in the field. These instrumentsstand up to the use and abuse of everyday service andelectrically insulate the user from potential shockhazards. They have electronic overload protectionagainst accidental application of voltage to resistanceand continuity circuits. These characteristics,

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combined with their rugged construction, make themdurable and reliable instruments.

The maintenance and cleaning of theseinstruments are easy. Maintenance consists of periodiccleaning, battery replacement, fuse replacement, andrecalibration. Calibration on these meters should beperformed every year. The exterior of the instrumentcan be cleaned with a soft, clean cloth to remove anyoil, grease, or grime from the exterior of theinstrument. Never use liquid solvents or detergents. Ifthe instrument gets wet for any reason, dry theinstrument using low-pressure “clean” air at less than25 psi. Use care and caution while drying around thedisplay protector and areas where water or air couldenter the interior of the instrument.

CAUTION

All resistance measurements should be takenon de-energized circuits ONLY!

WARNING

When using compressed air for cleaning, wearchemical splash goggles. Do not direct the airtoward eyes or skin.

MAINTENANCE OF DISTRIBUTIONEQUIPMENT

The elements, accidents, and willful vandalism arethe cause of most damage to power distributionequipment. To repair these damages, the linemanrequires experience, a total commitment to safety, andthe knowledge to accomplish repairs to the system asquickly and economically as possible.

The maintenance required on the poles, timbers,and crossarms in a power distribution system isminimal. Normally, this equipment lasts for a period of20 years or more. However, the following problemsmay occur and create a need for maintenance action:

A pole can settle and require straightening.

Wood can shrink and cause all hardware tobecome loose and require tightening.

Over time, guys stretch and require re-tensioning.

Insulators get dirty and require cleaning,especially around sea water where there is salt inthe air.

Connections become loose with age and must bere-torqued to prevent hot spots.

In time, conductors stretch and require re-sagging.

INTERFERENCE ELIMINATION

Another important area of maintenance is noiseinterference elimination in the power distributionsystem.

Power lines may be a source of interference withradio communications. Conductors, insulators, andhardware contribute their share by means of sparkdischarges, localized corona discharge, and crossmodulation.

Spark Discharges

Spark discharges occur when localized excessivevoltage stress exists. A conductor may becomepartially insulated by corrosion products or aninsulator partially conductive because of cracks. Athird source of stress occurs when a conductor isseparated from another metallic part on a pole only by asmall air gap.

Corona Discharge

“Corona” is defined as the luminous discharge dueto ionization of the air in the vicinity of a conductorwhen the voltage gradient exceeds a certain criticalvalue.

Cross Modulation

Cross modulation (often the result of a corrodedconnection that causes nonlinear rectification ofcurrents) may occur when splices are made by twistingthe conductors, rather than using a tighter mechanicalsplice. Additionally, when conductors of dissimilarmetals are joined, corrosion occurs unless specialconnectors designed for the specific combination ofmetals are used.

Remedies for conductor, insulator, and hardwareinterference are relatively simple. Remember, thecondition for hardware interference is set up whenevertwo pieces of hardware are not securely bonded to eachother or are permanently separated by too short an airgap.

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DISTRIBUTION SAFETY EQUIPMENT

As the project supervisor or crew leader. you mustreview the work plan with all linemen before the startof the project. This conference lets all crew membersknow what their responsibilities are and whatprotective equipment and correct tools will be neededto safely and efficiently complete the assignment.Some of the most common pieces of safety equipmentthat you may use to ensure that your project iscompleted without incident are described below.

Rubber Gloves

The most important article of protection for alineman or a cableman is a good pair of rubber gloveswith the proper dielectric strength for the voltage of thecircuit to be worked on. Leather protector glovesalways must be worn over the rubber gloves to preventphysical damage to the rubber while work is beingperformed. When the rubber gloves are not in use, theyshould be stored in a canvas bag to protect them frommechanical damage or deterioration from sunrays.Rubber gloves always should be given an air test by thelineman or cableman each day before the work isstarted or whenever the workman encounters an objectthat may have damaged the rubber gloves.

The American National Standards Institutestandard ANSI/ASTM D120, Rubber InsulatingGloves, covers lineman’s rubber glove specifications.

The proof-test voltage of the rubber gloves shouldnot be construed to mean the safe voltage on which thegloves can be used.

The maximum voltage on which gloves safely canbe used depends on many factors including the careexercised in their use; the care followed in handling,storing, and inspecting the gloves in the field; theroutine established for periodic laboratory inspectionand test: the quality and thickness of the rubber; thedesign of the gloves: and other factors such as age,usage. and weather conditions.

Inasmuch as gloves are used for personalprotection and a serious personal injury may result ifthey fail while in use. an adequate factor of safetyshould be provided between the maximum voltage onwhich they are permitted to be used and the voltage atwhich they are tested.

Rubber insulating gloves should be thoroughlycleaned. inspected. and tested regularly by competentpersonnel.

Rubber Sleeves

While a lineman is working on high-voltagedistribution circuits. rubber sleeves should be wornwith rubber gloves to protect the arms and shoulders ofthe lineman. Rubber insulating sleeves must be treatedwith care and inspected regularly, by the linemen in amanner similar to that described for rubber insulatinggloves.

The rubber insulating sleeves should bethoroughly cleaned. inspected. and tested regularly bycompetent personnel.

Rubber Insulating Line Hose

Primary distribution conductors can be coveredwith rubber insulating line hose to protect the linemanfrom an accidental electrical contact (fig. 4-50). Theline hoses are manufactured in various lengths withinside-diameter measurements that vary from 1 to 1l/2 inches and must be tested to meet the required linevoltage. The lineman should be sure that the voltagerating ofthe line hose provides an ample safety factorfor the voltage applied to the conductors to becovered.

All line hoses should be cleaned and inspectedregularly. A hand crank wringer can be used to spreadthe line hose to clean and inspect it for cuts or coronadamage.

The rubber insulating line hose should be tested forvoltage according to the specifications at scheduledintervals.

In-service care of insulating line hose and coversis specified in ANSI/ASTM D1050 standard.

Figure 4-50.—Rubber insulating line hose used to coverprimary conductors.

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Rubber Insulating Insulator Hoods

Pin type or post type of distribution primaryinsulators can be covered by hoods. The insulator hoodproperly installed will overlap the line hose, providingthe lineman with complete shielding from theenergized conductors.

Insulator hoods, like all other rubber insulatingprotective equipment, must be treated with care, keptclean, and inspected at regular intervals. Canvas bagsof the proper size attached to a handline should be usedto raise and lower the protective equipment when it isto be installed and removed.

handles are knotted through holes in the overlap area ofthe cover.

Rubber Insulating Blankets

Odd-shaped conductors and equipment usuallycan be covered best with a rubber insulating blanket.The blankets, like other protective equipment, mustreceive careful treatment. The rubber insulatingblankets are stored in canvas rolls or metal canisters toprotect them when they are not in use. The blankets canbe held in place by ropes or large wooden clamps.

In-service care of insulating blankets is specifiedin ANSI/ASTM D1048 standard.

Conductor CoversSafety Hat

A conductor cover, fabricated from high-dielectricpolyethylene, clips on and covers conductors up to 2inches in diameter. A positive air gap is maintained bya swinging latch that can be loosened only by a one-quarter turn with a clamp stick.

Insulator Covers

Insulator covers are fabricated from high-dielectric polyethylene and are designed to be used inconjunction with two conductor covers. The insulatorcover fits over the insulator and locks with a conductorcover on each end. A polypropylene rope swings underthe crossarm and hooks with a clamp stick, thuspreventing the insulator cover from being movedupward by bumping or wind gusts.

Crossarm Covers

High-dielectric-strength polyethylene crossarmcovers are used to prevent tie wires from contacting thecrossarm when conductors adjacent to insulators arebeing tied or untied. It is designed for single- ordouble-arm construction with slots provided for thedouble-arm bolts. Flanges above the slots shield theends of the double-arm bolts.

Pole Covers

Polyethylene-constructed pole covers aredesigned to insulate the pole in the area adjacent tohigh-voltage conductors. The pole covers are availablein various lengths. Positive-hold polypropylene rope

Hard hats, or safety hats, are worn by linemen,cablemen, and groundmen to protect the workeragainst an impact from falling or moving objects andagainst accidental electrical contact of the head andenergized equipment. In addition, hard hats protect theworker from sunrays, cold, rain, sleet, and snow. Thefirst combined impact-resisting and electrical-insulating hat was introduced in 1952. The hat wasdesigned “to roll with the punch” by distributing theforce of a blow over the entire head. This feature isaccomplished’ by a suspension band which holds thehat about an inch away from the head and lets the hatwork as a shock absorber.

The hard hat is made of fiber glass, or plasticmaterial, and has an insulating value of approximately20,000 volts. New helmets are manufactured towithstand a test of 30,000 volts without failure. Theactual voltage that the hat will sustain while beingworn depends upon the cleanliness of the hat, weatherconditions, the type of electrode contacted, and othervariables. The wearing of safety hats by linemen andcablemen has greatly reduced electrical contacts.

Physical injuries to the head have been practicallyeliminated as a result of workers on the ground wearingprotective helmets. The Occupational Safety andHealth Act of 1970 and most companies' safety rulesrequire linemen, cablemen, and groundmen to wearsafety hats while performing physical work.Specifications for safety hats are found in ANSIStandard Z89.1, Protective Headwear for IndustrialWorkers-Requirements.

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CHAPTER 5

INTERIOR WIRING

INTRODUCTION

This chapter will help you understand theprinciples of interior wiring. The requirements forinstalling electrical systems are found in the currentedition of the National Electrical Code® (NEC®).The requirements are specific and detailed, and theychange somewhat as the complexity of the systemincreases. Therefore, the Code should be checked forproper installation of electrical systems.

INTERIOR SYSTEMS BELOWGRADE

An electrical system that is installed in concrete orin direct contact with the earth is considered to be asystem below grade.

Below grade conduit layout and direct buried cableor other raceways must be installed to meet theminimum cover requirements of table 5-1. Underbuildings, underground cables must be in a racewaythat is extended beyond the outside walk of thebuilding. Direct buried cables emerging from theground will be in protected enclosures or racewaysextending from the minimum cover distance, requiredby table 5-1, below grade to a point at least 8 feet abovefinished grade. There is no requirement for theprotection of direct buried cables in excess of 18 inchesbelow the finished grade.

Conduit in concrete buildings can be installedwhile the building is being erected. The outlets shouldbe attached to the forms, and the conduits betweenoutlets should be attached to reinforcing steel withmetal tie wires so that the concrete can be pouredaround them. When several conduits pass through awall, partition, or floor, a plugged sheet-metal tubeshould be set in the forms to provide a hole for them inthe concrete. When a single conduit passes through awall, partition or floor, a nipple or a plugged sheet-metal tube can be set in the forms.

Ferrous or nonferrous metal raceways, cablearmor, boxes, cable sheathing, cabinets, elbows,couplings, fittings, supports, and support hardwaremay be installed below grade. These materials alsomay be installed in areas subject to severe corrosive

influences when made of material judged suitable forthe condition or when provided with corrosionprotection approved for the condition.

WET AND CORROSIVE INSTALLATIONS

Underground-feeder cable and branch-circuitcable provide an economical wiring system for wet andcorrosive installations. Type UF two-conductor cableresembles Type USE service-entrance cable in generalappearance.The insulation is a plastic compound.NEC® statements with respect to its use are as follows:Underground-feeder and branch-circuit cable may beused underground, including direct burial in the earth,as feeder or branch-circuit cable when provided withovercurrent protection not in excess of the ratedcurrent-carrying capacity of the individual conductors.If single-conductor cables are installed, all cables ofthe feeder circuit, subfeeder circuit, or branch circuit,including the neutral and equipment groundingconductor, if any, will be run together in the sametrench or raceway. If the cable is buried directly in theearth, the minimum burial depth permitted is 24 inchesif the cable is unprotected and 18 inches when asupplemental covering, such as a 2-inch concrete pad,metal raceway, pipe, or other suitable protection, isprovided. Type UF cable may be used for interiorwiring in wet, dry, or corrosive locations under therecognized wiring methods of the Code, and wheninstalled as a nonmetallic-sheathed cable, it willconform with the provisions of the Code and be of amulticonductor type. Type UF cable also must be of amulticonductor type if installed in a cable tray.

Type UF cable will not be used (1) as service-entrance cable, (2) in commercial garages, (3) intheaters, (4) in motion-picture studios, (5) in storage-battery rooms, (6) in hoistways, (7) in any hazardouslocation, (8) embedded in poured cement, concrete, oraggregate except as provided in the Code, and (9)where exposed to direct rays of the sun unlessidentified as sunlight-resistant.

MARKINGS

Ungrounded conductors are available as singleor multiconductor cables. These cables are clearlymarked to identify them as grounded and grounding

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Table 5-1.—Minimum Cover Requirements for 0 to 600 Volts (Burial in Inches)

Minimum Cover Requirements, 0 to 600 Volts,Burial in Inches

Cover is defined as the shortest distance measured between a point on the top surface of any direct-buriedconductor, cable, conduit or other raceway and the top surface of finished grade, concrete, or similar cover.

Type of Wiring Method or Circuit

See Note 1 See Note 2 See Note 3

Rigid

See Note 4 See Note 5

Lighting Limitedto Not Morethan 30 Volts

Encasement or and InstalledOther with Type

Approved UF or in OtherRaceways Identified Cable

or Raceway

ResidentialBranch

Circuits Rated120 Volts or

Lesswith GFCIProtection

and MaximumOvercurrentProtection of20 Amperes

Circuits forControl

of Irrigation andLandscape

Rigid Metal Nonmetallic

Conduit orConduit

IntermediateApproved for

MetalDirect Burial

ConduitWithoutConcrete

Location of Direct BurialCables or

ConductorsWiring Method

or Circuit

6 18 12 6All locations notspecified below

24

In trench below 2- 18 6 12 6 6inch thick concrete orequivalent

Not used Not used In raceway only In raceway onlyUnder a building In raceway only

Under minimum of 4-inch concrete exteriorslab with vehiculartraffic and the slabextends not less than6 inches beyond theunderground

18 4 4 4 inches forraceway and 6

inches for directburial

4 inches forraceway and 6

inches for directburial

installation

Under Streets.highways, roads,alleys, driveways. andparking lots

24 24 24 24 24

One and two family 18 18 18 12 18dwelling driveways,parking areas. andother purposes

In or under airport 18 18 18 18 18runways includingadjacent areas wheretrespassingprohibited

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Table 5-1.—Minimum Cover Requirements for 0 to 600 Volts (Burial in Inches)—Continued

In solid rock wherecovered by

2 inches, 2 2 2 inches, 2 inches,raceway only raceway only raceway only

minimum of 2inches concreteextending down torock

Note 1. For SI units; one inch = 25.4 millimeters.Note 2. Raceways approved for burial only where concrete encased will require concrete envelope not less

than 2 inches thick.Note 3. Lesser depths are permitted where cables and conductors rise for terminations or splices or where

access is otherwise required.Note 4. Where one of the conduit types listed in columns 1 through 3 is combined with one of the circuit

types in columns 4 and 5, the shallower depth of burial is permitted.

conductors. Ungrounded conductors will bedistinguished by colors other than white, natural gray,or green, or by a combination of color plusdistinguishing marking. Distinguishing markings alsowill be in a color other than white, natural gray, orgreen. and will consist of a stripe or stripes or aregularly spaced series of identical marks. Distin-guishing markings will not conflict in any manner withthe surface markings required by the NEC®.

UNDERFLOOR RACEWAY SYSTEMS

Underfloor raceway systems are used in officebuildings for the installation of the wiring fortelephone and signal systems and for convenienceoutlets for electrically operated office machinery.They provide a flexible system by which the locationof outlets may be changed easily to accommodate therearrangement of furniture and partitions. The NEC®

allows their use when embedded in concrete or in theconcrete fill of floors. Their installation is allowedonly in locations that are free from corrosive orhazardous conditions. No wires larger than themaximum size approved for the particular racewaywill be installed. The voltage of the system must notexceed 600 volts. The total cross-sectional area of allconductors in a duct must not be greater than 40percent of the interior cross-sectional area of the duct.

An underfloor raceway system consists of ductslaid below the surface of the floor and interconnectedby means of special cast-iron floor junction boxes. Theducts for underfloor raceway systems are made ofeither fiber or steel. Fiber ducts are made in twotypes-the open-bottom type and the completelyenclosing type. Steel ducts are always of the

completely enclosing type, usually having arectangular cross section. In the underfloor racewaysystem, provision is made for outlets by means ofspecially designed floor-outlet fittings that arescrewed into the walls of the ducts. When fiber ductsare used, the duct system is laid in the floor with orwithout openings or inserts for outlets. After the floorhas been poured and finished as desired, the outletfittings are installed into inserts or at any points alongthe ducts at which outlets are required. The method ofinstalling outlet fittings is described in the nextparagraph. When steel ducts are used, provision for theoutlet fittings must be made at the time that the ductsare laid before the floor or floor fill is poured. The steelducts are manufactured with threaded openings foroutlet connections at regularly spaced intervals alongthe duct. During the installation of the raceway and thefloor, these outlet openings are closed with speciallyconstructed plugs whose height can be adjusted to suitthe floor level. For telephone and similar circuits,much wider ducts can be obtained.

In general, underfloor raceways should beinstalled so that there is at least 3/4 inch of concrete orwood over the highest point of the ducts. However, inoffice-approved raceways, they may be laid flush withthe concrete if covered with linoleum or equivalentfloor covering. When two or three raceways areinstalled flush with the concrete, they must becontiguous with each other and joined to form a rigidassembly. Flat-top ducts over 4 inches wide but notover 8 inches, spaced less than 1 inch apart, must becovered with at least 1/2 inch of concrete. It is standardpractice to allow 3/4-inch clearance between ducts runside by side. The center line of the ducts should form a

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straight line between junction boxes. If the spacingbetween raceways is 1 inch or more, the raceway maybe covered with only 1 inch of concrete. All the jointsin the raceway between sections of ducts and atjunction boxes should be made waterproof and havegood electrical contact so that the raceways will beelectrically continuous. Metal raceways must beproperly grounded.

To establish outlets in a preset system after thefinish is in place, you have to determine the location ofthe insert. Inserts can be located by using an insertfinder. Once inserts are located, the flooring is chippeddown to expose the insert cap. The cap is removed anda hole cut in the duct so the wires can be fished throughand connected to the receptacle.

The following procedures should be used to installan outlet fitting at any point in a completely enclosedunderfloor fiber raceway:

1. Locate the duct line.

2. Cut a hole in linoleum or other floor covering.

3. Chip a hole down to duct.

4. Cut a hole in the duct.

5. Screw insert into the. duct.

6. Anchor the insert with grouting compound.

7. Screw the outlet into the insert.

The special tools, provided by the manufacturer,for this purpose should be used to ensure satisfactoryworkmanship.

Combination junction boxes accommodating thetwo or three ducts of multiple-duct systems may beused, provided separate compartments are furnished inthe boxes for each system. It is best to keep the samerelative location of compartments for the respectivesystems throughout the installation.

All the joints in or taps to the conductors must bemade in the junction boxes. No joints or taps should bemade in the ducts of the raceway or at outlet insertpoints.

INTERIOR SYSTEMS ABOVE GRADE

An interior system above grade starts at the servicedrop and covers all the conduit layouts (excluding in-the-slab), communication, power, and lightingcircuits. You must be aware of the NEC® rules thatgovern industrial and residential interior electricalsystems. To gain additional knowledge, you may read

the following: Standard Handbook for ElectricalEngineers and the American Electrician’s Handbook.

CONDUIT LAYOUT

Follow the construction blueprints and speci-fication when laying out conduit runs. Remember,most prints will not show the direction of the conduitrun. They only direct you to install a circuit from thedistribution panel to a location where a electricalapparatus will be serviced. When you install anycircuit, complete the service installation with theshortest route possible.

Properly bent conduit turns look better thanelbows and, therefore, are preferable for exposed work(fig. 5-1). If bends are formed to a chalk line, draw thechalk line as suggested in figure 5-2. The conduits can

Figure 5-1.—Right-angle turns with elbows.

Figure 5-2.—Forming a conduit to chalk lines.

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be placed parallel at a turn in a multiple run, as shownin figure 5-3. If standard elbows are used, it isimpossible to place them parallel at the turns. They willhave an appearance similar to the one shown in figure5-1.

Except as discussed in the NEC®, metal raceways,cable armor, and other metal enclosures for conductorswill be joined together into a continuous electricconductor and will be connected to all the boxes,fittings, and cabinets to provide effective electricalcontinuity. Raceways and cable assemblies will bemechanically secured to boxes, fittings, cabinets, andother enclosures. This action ensures electricalcontinuity of metal raceways and enclosures.

WIRING OF BUILDINGS

Normally the power-distribution feeder from thepower pole to a building is secured to the building withan insulator bracket. Brackets should be mounted highenough so the power feeders are never suspendedlower than 18 feet over driveways and 10 feet overwalkways.

Insulator bracket service-entrance conductors rundown the side of the building to a point where theyenter the building and connect to the service-entrancepanel. For commercial and industrial wiring, thegreatest percentage of wiring will be installed in a

Figure 5-3.—Right-angle turns with bent conduit.

conduit or a raceway. Service-entrance cable should beused for this purpose.

Armored cable or nonmetallic-sheathed cableshould be used for the interior wiring of the building.

GROUNDING

At each building, the wiring system must begrounded. This provision is in addition to the ground atthe power pole. Grounds must be established at eachpoint of entrance to each building; and, if possible, allthese grounds should be tied together on drivengrounds. Also, for added safety, the water systemshould be tied at each building to the driven ground forthat building. A well-grounded wiring system adds tothe safety of the entire installation.

WIRING SYSTEM GENERALPROVISIONS

The following discussion applies to the types ofwiring used for voltages up to 600 volts, unlessotherwise indicated. Each type of insulated conductoris approved for certain uses and has a maximumoperating temperature. If this temperature is exceeded,the insulation is subject to deterioration. In recentyears, modified ethylene tetrafluoroethylene (2 andZW) and perfluoroalkoxy (PFA and PFAH) cableshave been allowed for high-temperature operations.Each conductor size has a maximum current-carryingcapacity, depending on the type of insulation andconditions of use.

Conductors of more than 600 volts should notoccupy the same enclosure as conductors carrying lessthan 600 volts, but conductors of different light andpower systems of less than 600 volts may be groupedtogether in one enclosure if all are insulated for themaximum voltage encountered. Communicationcircuits should not occupy the same enclosure withlight and power wiring.

Boxes or fittings must be installed at all outlets, atswitch or junction points of raceway or cable systems,and at each outlet and switch point of concealed knob-and-tube work.

PROVISIONS APPLYING TO ALLRACEWAY SYSTEMS

The number of conductors, permitted in each sizeand type of raceway, is definitely limited to provideready installation and withdrawal. For conduit andelectrical metallic tubing, refer to the NEC®.

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Raceways, except surface-metal molding, must beinstalled as complete empty systems, the conductorsbeing drawn in later. Conductors must be continuousfrom outlet to outlet without splice. except in auxiliarygutters and wireways.

Conductors of No. 8 AWG and larger must bestranded. Raceways must be continuous from outlet tooutlet and from fitting to fitting and will be securelyfastened in place.

All conductors of a circuit operating on alternatingcurrent, if in a metallic raceway’, should be run in oneenclosure to avoid inductive overheating. If, owing tocapacity, not all conductors can be installed in oneenclosure, each raceway used should contain acomplete circuit (one conductor from each phase).

Rigid-metal conduit, intermediate metal conduit,and electrical metallic tubing are the systems generallyused where wires are to be installed in raceways. Bothconduit and tubing may be buried in concrete fills ormay be installed exposed. Wiring installed in conduitis approved for all classes of buildings and for voltagesboth above and below 600 volts. Certain restrictionsare placed on the use of tubing; refer to the NEC®.

LIGHTING AND POWER SYSTEMS

Lighting and power systems start at thepanelboards. Refer to the NEC® during the installationof the lighting and power circuits for further guidance.The wiring layout in each of these illustrationsdetermines how the component parts in the circuit willbe connected to one another and where the wires willbe routed. Careful planning in the wiring layout canresult in substantial savings by eliminating long runs ofexcess wire. It should be pointed out that the wire runsthat are shown in the actual construction illustrationmay not be the most economical use of wire. Thesewire runs are laid out in a very smooth and definitepattern to make the drawing easier to follow. In manycases, wire runs shown at right angles should be rundiagonally to conserve wire. When cable runs arerouted on the jobsite, shortening the runs will result inlower installation costs.

SERVICES AND FEEDERS

No limit is placed on the electrical capacity ofservice conductors and service protection used inbringing the electric supply into a building, since onlyone supply should be introduced whenever possible.Near the point of entrance of the supply, the heavy-service conductors are tapped by feeders that conductthe electricity to panelboards at various load centers in

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the building where the final branch circuits whichsupply individual lighting, heating, and power outletsoriginate. No limits are placed on the electricalcapacity of feeders; but, for practical purposes, theyare limited in size by the difficulty of handling largeconductors and raceways in restricted building spaces,by voltage drop, and by economic considerations.

Each lighting fixture, motor, heating device. orother item of equipment must be supplied by either abranch circuit for grouped loads, by an individualbranch circuit, or by a motor branch circuit.

LIGHTING AND APPLIANCE BRANCH-CIRCUIT PANELBOARDS

In solving all installation problems withpanelboards, the first consideration is to determinewhether the panelboard will be considered a lightingand appliance branch-circuit type. The NEC® rules aremuch stricter for lighting and appliance branch-circuitpanelboards than for other types.

The Code defines a lighting and appliance branch-circuit panelboard as one having more than 10 percentof its overcurrent devices rated 30 amperes or less forwhich neutral connections are provided. For example,if any panelboard with less than 10 overcurrent devicescontains one overcurrent device rated at 30 amperesfor which neutral connections are provided, it would beconsidered a lighting and appliance branch-circuitpanelboard (1 ÷ 9 = 11%).

In another example, panelboards that supply loadswithout any neutral connections are not consideredlighting and appliance branch-circuit types whether ornot the overcurrent devices are 30 amperes or less.

When it is determined that a panelboard is alighting and appliance branch-circuit type, thefollowing NEC® rules apply:

1. Individual protection, consisting of not morethan two main circuit breakers or sets of fuses having acombined rating not greater than that of the panelboard,is required on the supply side. This main protection maybe contained within the panelboard or in a separateenclosure ahead of it. Two exceptions to the Code ruleare as follows:

a. Individual protection is not required whenthe panelboard feeder has overcurrent protection notgreater than that of the panelboard. For example, two400-ampere panelboards can be connected to the samefeeder if the feeder overcurrent device is rated or set at400 amperes or less.

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b. Individual protection is not required wheresuch existing panelboards are used as serviceequipment in supplying an individual residentialoccupancy. For example, take a split-bus panelboard inwhich the line section contains three to six circuitbreakers or fuses, none of which are rated 20 amperes orless. In such an arrangement, one of the mainovercurrent devices supplies the second part of thepanel that contains l5- or 20-ampere branch-circuitdevices. The other main overcurrent devices (over 20amperes) supply feeders or major appliances, such ascooking equipment, clothes dryers, water heaters, orair-conditioning equipment (fig. 5-4). Thisarrangementis permitted only for existing panelboards in existingindividual residential occupancies.

2. A lighting and appliance branch-circuitpanelboard is limited to not over 42 overcurrent devices(excluding the main overcurrent devices) in any onecabinet or cutout box (fig. 5-5). When such devices arenumbered, a single-pole circuit breaker is counted asone overcurrent device; a two-pole circuit breaker, astwo overcurrent devices; and a three-pole circuitbreaker, as three overcurrent devices.

In addition, the panelboards will be provided withphysical means to prevent the installation of moreovercurrent devices than the panelboard was designed,rated, and approved to handle. Figure 5-6 shows asuitable arrangement for overcurrent devices.

Figure 5-4.—Typical arrangement of a split-bus lightingpanelboard.

Figure 5-5.—Typical arrangement that shows NEC® rules forlighting panelboards.

Figure 5-6.—Suitable arrangement for an existing 200-amperelighting panelboard used as service equipment forindividual residential occupancy.

A typical lighting panelboard is a circuit-breakertype with a main 200-ampere circuit breaker andthirty-two 20-ampere single-pole breakers. This typeof panel is used for a four-wire, three-phase, groundedneutral system. The main breaker is three-pole.

Other NEC® provisions that apply to all types ofpanelboards are as follows:

1. Panelboards, equipped with snap switches rated30 amperes or less, will have overcurrent protection notin excess of 200 amperes. Circuit breakers are notconsidered snap switches.

2. Panelboards that have switches on the load sideof any type of fuse will not be installed except for use asservice equipment. Panelboard equipment with the snapswitch is on the line side of the plug fuses and satisfiesthe Code.

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3. The total load on any overcurrent device,located in a panelboard, will not exceed 80 percent of itsrating. If in normal operation, the load will becontinuous (3 hours or more) unless the assemblyincluding the overcurrent device is approved forcontinuous duty at 100 percent of its rating.

Power-distribution panels are similar to thefeeder-distribution type. They have bus bars normallyrated up to 1,200 amperes at 600 volts or less andcontain control and overcurrent devices sized to matchconnected motor or other power circuit loads.Generally, the devices are three-phase.

Special panelboards. containing relays andcontactors, can be obtained and installed when remotecontrol of specific equipment is specified. A thoroughknowledge of all the available types of panelboardsaids in the selection and installation of the proper unit.

Service-equipment panelboards, for loads up to800 amperes, containing six or fewer main fusedswitches, fused pullouts, or circuit breakers areavailable. These panels constitute service equipmentand frequently contain split buses that supply branchcircuit or feeder overcurrent devices installed in thesame enclosure (figs. 5-4 and 5-6).

Feeder distribution panels generally containcircuit overcurrent devices rated at more than 30amperes to protect subfeeders that extend to smallerbranch-circuit panelboards.

BRANCH CIRCUITS FORGROUPED LOADS

The uses and limitations of the common types ofbranch circuits are outlined in the Summary of Branch-Circuit Requirements (NEC® table 210-24). Lightingbranch circuits may carry loads as high as 50 amperes,although florescent lighting is limited to use on circuitsof 15-ampere or 20-ampere rating. Such circuits areextensively used in commercial and industrialoccupancies. Branch circuits, supplying convenienceoutlets for general use in other than manufacturingareas, are usually limited to a maximum of 20 amperes.The type of outlet required for heavier capacity circuitsusually will not accommodate the connection plugfound on portable cords, lamps, motor-driven officemachinery, and so forth.

INDIVIDUAL BRANCH CIRCUITS

Any individual piece of equipment (exceptmotors) also may be connected to a branch circuitmeeting the following requirements: Conductors must

be large enough for the individual load supplied.Overcurrent protection must not exceed the capacity ofthe conductors or 150 percent of the rating of theindividual load if the single-load device is a nonmotor-operated appliance rated at 10 amperes or more. Only asingle outlet or piece of equipment may be supplied.

MOTOR BRANCH CIRCUITS

Because of the peculiar conditions obtained duringthe starting period of a motor and because it may besubjected to severe overloads at frequent intervals,motors, except for very small sizes, are connected tobranch circuits of a somewhat different design fromthat previously discussed.

CONDUCTORS

The Code covers general requirements forconductors and their type designations, insulations?markings, mechanical strengths, ampacity ratings, anduses. These requirements do not apply to conductorsthat form an integral part of the equipment, such asmotors, motor controllers, and similar equipment, or toconductors specifically provided for elsewhere in theCode.

Conductors must be insulated except wherecovered or bare conductors are specifically permittedby the NEC®. The Code covers the insulation ofneutral conductors of a solidly grounded high-voltagesystem. When stranded conductors are installed, theCode states that stranded conductors installed inraceways must be a size No. 8 or larger with thefollowing exceptions:

Exception No. 1: When used as bus bars or inmineral-insulated, metal-sheathed cable

Exception No.2: When bonding conductors arerequired

Conductors in Parallel

Aluminum, copper-clad aluminum, or copperconductors of size 1/0 and larger, in each phase of thecurrent; neutral; and grounded circuit conductors maybe connected in parallel (electrically joined at bothends to form a single conductor).

Exception No. 1: Conductors in sizes smaller thanNo. l/O AWG will be permitted to run in parallel tosupply control power to indicating instruments,contactors, relays, solenoids, and similar controldevices provided:

1. They are contained within the same raceway orcable

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2. The ampacity of each individual conductor issufficient to carry the entire load current sharedby the parallel conductors

3. The overcurrent protection is such that theampacity of each individual conductor will notbe exceeded if one or more of the parallelconductors become inadvertently disconnected

Equipment GroundingConductors

Bare, covered, or insulated grounding conductorswill be permitted. Individually covered or insulatedgrounding conductors will have a continuous outerfinish that is either green or green with one or moreyellow stripes.

1.

2.

3.

Stripping the insulation from the entire exposedlength

Coloring the exposed insulation green

Marking the exposed insulation with green tapeor green colored adhesive labels

Exception No. 1: An insulated or coveredconductor larger than No. 6 will be permited, at thetime of installation, to be permanently identified as agrounding conductor at each end and at every pointwhere the conductor is accessible. Identification willbe accomplished by one of the following means:

1. Stripping the insulation or covering from theentire exposed length

The following paragraphs discuss conductors invertical conduits. You may not work very much withmultistory buildings but the knowledge is veryimportant. Conductors in vertical conduits must besupported within the conduit system, as shown in table5-2.

The following methods of supporting cables willsatisfy NEC® requirements:

2. Coloring the exposed insulation or covering 1. Approved clamping devices are constructed ofgreen or use insulated wedges inserted in the ends of the

3. Marking the exposed insulation or coveringwith green colored tape or green coloredadhesive labels

Exception No. 2: Where the conditions ofmaintenance and supervision assure that only qualifiedpersons will service the installation, an insulatedconductor in a multiconductor cable will be permitted,at the time of installation, to be permanently identifiedas a grounding conductor at each end and at every pointwhere the conductor is accessible by one of thefollowing means:

Table 5-2.—Spacing of Vertical Conductors Support

CONDUCTORS (IN FEET)

CONDUCTOR SIZE Aluminum or

Copper-Clad AluminumCopper

Not greater than Not greater than

No. 18 through No. 8 100 100

No. 6 through No. 0 200 100

No. 00 through No. 0000 180 80

211,601 through 350,000 cmil 135 60

350,001 through 500,000 cmil 120 50

500,001 through 750,00 cmil 95 40

Above 750,000 cmil 85 35

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conduits (fig. 5-7). With cables having varnished-cambric insulation, it also may be necessary to clampthe conductor.

2. Junction boxes may be inserted in the conduitsystem at required intervals. Insulating supports of anapproved type must be installed in the junction boxesand secured in a satisfactory manner to withstand theweight of the attached conductors. The boxes must beprovided with proper covers.

3. The cables may be supported in junction boxesby deflecting them (fig. 5-8) not less than 90 degreesand carrying them horizontally to a distance not lessthan twice the diameter of the cable. The cables may becarried on two or more insulating supports andadditionally secured by tie wires. When this method isused, the cables will be supported at intervals notgreater than 20 percent of those mentioned in thepreceding table.

TESTING ELECTRICAL CIRCUITS

In this section, you will find out how easy it is toassist and train your crew in troubleshooting. Many

Figure 5-7.—Gable support screwed on the end of a conduitand the one piece plug type.

different types of electrical multimeters are availableto assist you. Electrical circuits can be tested safely andinexpensively with a neon tester (fig. 5-9). Mostelectrical problems can be solved just by determiningthe presence or absence of voltage.

CHECKING FOR A DEFECTIVERECEPTACLE

One of the most common tests made with a neontester is determining whether a receptacle isproviding power. Figure 5-10 shows the first step intesting a receptacle. Each lead of the tester is firmlypressed into the receptacle slots to form a goodelectrical contact.

If voltage is present. the neon tester will glowsoftly for a 110-volt circuit and more brightly for a220-volt circuit. If the tester does not light, thereceptacle cover should be removed so that a secondvoltage check can be made at the terminals of thereceptacle (fig. 5-11). If voltage is present at theterminals but not at the receptacle, the receptacle isdefective and should be replaced. If voltage is notpresent at either the receptacle or its terminals, theproblem lies in the overload protection or in theelectrical circuit leading to the troubled receptacle.

When the problem is in the electrical circuitleading to the receptacle, check each splice or eachterminal point along the entire circuit for a break or aloose connection.

CHECKING FOR A DEFECTIVESWITCH

Determining whether a switch is defective requiresonly a simple two-step procedure. You must determinewhether voltage is reaching the switch and whethervoltage is passing through the switch.

Figure 5-12 shows how you can position the neontester to determine if voltage is reaching the switch.Figure 5-13 shows how you reposition the tester todetermine if voltage is going through.

With a grounded system, you need only touch themetal box and the terminals (figs. 5-12 and 5-13), oryou may find it necessary to remove the wire nut fromthe neutral wire and use the neutral as the other testpoint. If voltage is not present at either switch terminal,the problem lies in the overload protection or in theelectrical circuit leading to the troubled switch.

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Figure 5-8.—Supporting conductors in a vertical conductor run.

WARNING

Failure to secure power could result in afatal electrical shock. More people are killedby normal household current than highvoltage. When energized circuits are beingworked on, the worker should be trainedaccording to 29 CFR 1910.333 and use theprotective equipment specified in 29 CFR1910.335.

Figure 5-9.—Neon testers for 110/220-volt circuits.

When the problem is in the electrical circuitleading to the receptacle, each splice or terminal pointshould be checked along the entire circuit for a break orloose connection. Before this test procedure is started,be sure the power to the suspected switch has beenturned OFF.

Remove the faceplate from the switch and unscrewthe switch from the junction box. Pull the switch awayfrom the metal box and position it so that no bare wirescan touch the box. When the switch is in a SAFEposition, power may be restored and the test procedurestarted.

CHECKING FOR THE HOT WIRE

In remodeling you may find it necessary to checkwhich wires provide power to the circuit and whichwires merely continue on to feed other circuits. Theneon tester can simplify this procedure by individually

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Figure 5-10.—First step in testing an outlet with a neon tester.

identifying each pair of wires. The pair that is hot willcause the neon tester to glow.

The grounded system is easiest to check becauseonly the potential hot wires need to be disconnected,separated, and tested. Figure 5-14 shows how the wiresare separated and tested. The wire that causes the neontester to respond is the hot lead.

An ungrounded system can be checked just like agrounded system? except the solderless connector mustbe removed from the neutral wire and the neutral wiremust be used as a reference, as shown in figure 5-15.Figure 5-16 shows how to determine if voltage isreaching a light fixture. With the switch in the ONposition, the neon tester should light.

TESTING THE GROUND TERMINAL

A simple test procedure, as shown in figure 5-17,may be used to check each receptacle for ground.

Figure 5-11.—Using the neon tester to check for a defectivereceptacle.

One lead of the neon tester should be heldstationary on the ground terminal while the oppositelead is repositioned on each plug slot. If the receptacleis properly grounded, the neon light will light whenplaced in only one of the slots. If the light does not glowin either slot, the receptacle is not grounded.

TESTING CIRCUIT BREAKERS ANDFUSES IN CIRCUITS

When you are troubleshooting large electricalsystems, it is important to follow the systematicapproach: localize, isolate, and locate. It is never agood procedure to make haphazard measurements in asystem hoping that luck will lead to the problem.Testing circuit breakers and fuses in the circuit firstmay eliminate unnecessary troubleshooting. Practice

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Figure 5-12.—Checking a switch in the OFF position forproper operation.

safe habits. Remember that getting too friendly withelectricity can be a shocking experience.

Circuit Breaker

A circuit breaker operates much the same as aswitch-the breaker is either ON or OFF. The neontester lead is placed on the neutral bar and the otherlead is placed on the screw terminal of the circuitbreaker (fig. 5-18). If the breaker is good, the neontester will light when the breaker is in the ON positionand will not light when the breaker is in the TRIPPEDposition.

Figure 5-13.—Checking a switch in the ON position for properoperation.

If the neon tester remains lighted in both positions,the breaker is shorted and should be replaced. If theneon tester does not light in either position, the circuitbreaker is open and should be replaced. Remember toreset the circuit breaker.

Figure 5-14.—Technique for determining which wire is hot.

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Figure 5-15.—Checking for the hot wire in an undergroundsystem with neutral wire exposed.

Figure 5-16.—Technique for determining if voltage isreaching a light fixture.

Figure 5-17.—Checking for a properly grounded receptacle.

Figure 5-18.—Testing for proper operation of a circuitbreaker.

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Fuse

When a fuse is suspected of being defective, it maybe checked with a neon tester using the four-partprocedure shown in figure 5-19.

1. First determine if the voltage is present at the topof the fuses from the incoming lines. (Light shouldglow.)

2. Determine if the voltage is passing through thefuse. (If the neon tester fails to light, one or both fusesare defective.)

3. Check the left fuse to see if the voltage ispresent. If the light glows, the fuse is good; however, ifit fails to light, the fuse is defective. Shut off the powerand replace the fuse.

4. Check the right fuse to see if the voltage ispresent. If the light glows, the fuse is good; however, ifit fails to light, the fuse is defective. Shut off the powerand replace the fuse.

WARNING

To prevent electrical shock, do not replace thefuses unless the circuit is de-energized and then onlywith fuse pullers.

BENDING CONDUIT

Bending conduit is an art. Like all forms of art, themore often it is done correctly, the more proficient theartist becomes. It is recommended that you attend theSCBT 240.2 course that covers bending andinstallation of electrical conduits using mechanicalbenders. Keep in mind that practice will improve yourskills and always read and follow the manufacturer’sinstruction guide. Following the guide will normallyassure that you make top quality bends in a safe andefficient manner.

POWER BENDERS

Power benders are used for bending larger sizes ofelectrical metallic tubing (EMT), intermediatemetallic tubing (IMC), and rigid conduit. Powerbenders come in many types and sizes. Some of thecommon ones are the hydraulic one-shot, sweep, andthin-wall benders. As for the mechanical benders, thethin-wall and sweep benders are common. Thehydraulic benders use either a hand pump or an electricpump to move a shoe that does the actual bending.Figure 5-20 shows a hydraulic sweep bender that uses a

hand pump. By using different sizes of bending dies atdifferent locations on the tie bar, you can use thisbender to bend several types and sizes of conduit. Theprocedures for making the different types of bendswith power benders are very similar to those used withmanual benders. The main difference is that with thepower benders, the take-up for 90-degree bends andthe distance between bends for offsets will not be thesame. This difference occurs because you are dealingwith larger sizes of conduit or the shoes of the bendergive a different radius of bend. Because there are somany different types and manufacturers of benders,remember to check the manufacturer’s instructionguide before doing any bending.

BENDING FUNCTIONS AND SAFETY TIPS

In the following paragraphs, we will discuss somegeneral information concerning power benders. Thisinformation does not replace the manufacturer’sinstruction guide, but only acquaints you with somebasic functions and safety tips that you (as a crewleader) must be aware of.

When you are bending conduit, the bender must bein a horizontal position. When moving the bender anydistance, place the pipe supports and pins in a 4-inch to5-inch hole position. Then stand up the bender and rollit.

When connecting the high-pressure hose to thefemale quick-coupler on the end of the ram and theother end to the high-pressure pump female coupler,make sure that the quick-coupler is clean beforemaking the connection. For the correct procedures forremoving all the air from the pump and hoses, refer tothe manufacturer’s manual.

Some mechanical benders have an electricalpower pump that is used to apply pressure on the ram.In this case, to operate the hydraulic pump, the motormust be running. Also, the quickest way to stop theadvance of the ram is to stop the motor of the powerpump.

WARNING

Read the pump operating instructionsbefore operating the pump. Always place thecontrol lever in the return position beforestarting the electric motor pump.

Regardless of what hydraulic bender you use, youmust always check the manufacturer’s charts andtables for the minimum stub length. When the

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Figure 5-19.—Procedure used with a neon tester to isolate a defective fuse in a live circuit.

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Figure 5-20.—Hydraulic sweep bender with hand pump.

manufacturer’s tables and charts are not available, theconduit stub length must be equal to or greater than theminimum shown in table 5-3.

When bending conduit up to 90 degrees with abender that has a ram travel scale, you should makeyour bend according to the ram travel scale reading.

An offset bend requires two bends of the samedegree. To determine the distance between the twobends, you must first decide on the distance in inchesof the offset and the degree of bend your conduit

Table 5-3.—Conduit Size/Deductions/MininumStub Lengths

CONDUIT DEDUCT MINIMUM STUBSIZE LENGTH

1/2 1 15/16 10

3/4 1 1/2 10

1 1 7/8 13

1 1/4 2 3/8 15 13/16

1 1/2 2 3/4 18 3/4

2 3 1/4 21 9/16

2 1/2 4 1/8 25

3 4 15/16 28 l/8

3 1/2 5 3/4 31

4 6 1/2 33 7/8

routing requires. Remember that the maximumconduit size and offset in inches may restrict yourbend. Mark and bend your conduit according to thebenders manufacturers’ instructions, tables, and charts.

If you have access to a conduit pipe holder(normally for 1 1/4-inch to 4-inch conduit), it willsimplify your work by keeping the pipe in perfectalignment at all times, achieving an outstanding bend.When offset bends are being made, the pipe holderpermits making the first bend and then reversing thepipe end and making the second bend. The second bendwill then be 180 degrees opposite the first bend.

CAUTION

Before using any pipe bender, make surethe quick-lock pins are through the holes in thebottom frame and the eccentric pin is turnedclockwise past the ball lock. Also, make surethe correct sides of the pipe support pins are inthe proper holes. Failure to ensure correct pinplacement could result in damage to theconduit and/or the bender.

Occasionally conduit will require more bending.In this case, place the conduit in the bender andcontinue bending to the desired degree. This step is notnecessary when using the Bending Degree Indicator(used for exact bends and reduces the necessity tocorrect bending caused by springback) or when usingthe Bending Degree Protractor because the bend willbe accurate.

When you are bending long lengths of conduit,conduit pipe holders are very useful. Check themanufacturer’s instruction guide for tables and chartsthat give vital information about conduit bending kitattachments.

When you have to make a large sweep 90-degreeradius bend, you will need to get the operating manualof the bender you are using and follow the suggestedprocedures for marking the bend spacing and findingthe necessary center location.

One of the benders that you may use in the field isthe GreenleeTM 880 M2 Lightweight HydraulicBender. This bender is designed to make bends up to 90degrees on rigid conduit from 1/2 inch to 2 inchesinclusive. The 15-ton ram, the bending shoes, and theframe unit allow a complete 90-degree bend to be madewith one piston stroke. The units of the bender can berapidly and easily assembled for operation without anytools. By using the bending instructions and the piston

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scale, you can make accurate bends. To assure easyportabiliy, the manufacturer has designed the pipesupports for use as rollers; and parts are made of light-but-strong aluminum alloy whenever possible.

In the bending process, if the pipe is bent to thecorrect scale reading, overbends will not result.However: if you need to correct an overbend, you mustfollow the manufacturer’s instructions that cover thebender that you are using.

As mentioned earlier, bending conduit is an art. Themore you practice, the better you will be. Most bendingcharts show information on how to make bends to 15°.30°, 45°, 60°, 90°, 180° and offset bends. When degreesof bend other than these are required and it is importantthat the bend be accurate. the Bending Degree Indicatorshould be used. The Bending Degree Indicator isextremely accurate and is very easy to use. The indicatoralso should be used when making segment bends tocenter radii greater than those of the bending shoe.

CONDUIT SUPPORTS ANDINSTALLATION METHODS

To install conduit overhead and undergroundproperly, you need to review the appropriate articles ofthe Code. Conduit should run as straight and direct aspossible. There should never be more than theequivalent of four right-angle bends between outlets orfittings.

In installing exposed conduit runs where there areseveral conduits in the run. it is usually better to carry theerection of all of them together. rather than to completeone line before starting the others. If all are carriedtogether. it is easier to keep all the raceways parallel.particularly at turns. and chances are that the job will lookbetter.

Conduit can be supported on surfaces with pipestraps made in one-hole and two-hole types. On woodensurfaces, wood screws secure the straps in position. Onmasonry surfaces, machine screws that turn into leadexpansion anchors can be used. Wooden plugs shouldnever be used because no matter how well seasoned aplug appears to be, it usually will dry out to some extentand loosen in the hole. When laying out multiple-conduitruns, you must keep in mind the spacings between theconduits to permit proper placing of the straps. Thescrew-hole dimension (see table 5-4) enables you to orderscrews of the proper diameters to support the straps.

LOCATION OF CONDUIT SUPPORTS

The Code states that rigid-metal conduit will befirmly secured within 3 feet of each outlet box,junction box, cabinet, or fitting. The Code permits thisdistance to be increased to 5 feet where structuralmembers do not readily permit fastening within 3 feet.Rigid-metal conduit will be supported at least every 10feet; except that straight runs of conduit made up of

Table 5-4.—Spacings Requirements When Laying Out Multiple-Conduit Runs

Size of conduit Conduit. Conduit, Width of Distance Diameter of Size of wood screw(inches) width of height of conduit strap between screw hole required

opening opening (inches) centers of (inches)(inches) (inches) screw hole

(inches)

1/4 9/16 17/32 5/8 1-9/16 0.20 No. 8 × 5/8"

3/8 1 1/16 21/32 5/8 1-3/8 0.20 No. 8 × 3/4"

1/2 7/8 25/32 5/8 l-5/8 0.20 No. 8 × 3/4"

3/4 1/18 1 3/4 2-1/8 0.22 No. 10 × 3/4"

l 1-3/8 1-11/32 3/4 2-3/8 0.22 No. 10 × 7/8"

1-1/4 1-3/4 l-5/8 1-13/16 2-3/4 0.22 No. 10 × 1"

1-1/2 2 1-7/8 1-13/16 3 0.22 No. 10 × 1"

2 2-1/2 2-5/16 1 3-3/4 0.22 No. 10 × 1- 1/4"

2-1/2 2-3/4 2-15/16 7/8 4-3/3 0.25 No. 11 × 1- 1/4"

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approved threaded couplings may be secured as shownin table 5-5, provided such fastening preventstransmission of stress to terminations when conduit isdeflected between supports.

Table 5-5.—Spacing of Rigid-Metal Conduit Supports

CONDUIT SIZE RIGID-METAL SUPPORT(INCHES) (FEET)

1/2 and 3/4 10

1 12

1-1/4 and 1-1/2 14

2 and 2-1/2 16

3 and larger 20

CONDUIT HANGERS AND SUPPORTS

A variety of conduit hangers and supports and severalapplications are shown in figure 5-21. U-channelsupports are ideal for supporting several runs ofconduits. In laying out these supports, considerationshould be given to future conduit runs as well as thoseto be installed initially. It is a simple matter to provideU-channels or trapeze hangers with additional spacefor future conduits. This procedure greatly reduces thecost of installing new conduit at a later date. With theU-channel system, as shown in figure 5-21, specialclamps are slipped into the channel slot, and the topbolt of the clamp securely fastens the conduit tothe U-channel.

The U-channel can be directly fastened to a wall orceiling, or it can be attached to bolted threaded rod

Figure 5-21.—Common conduit supports.

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hangers suspended from ceilings, roof structures, orsimilar members.

Another excellent application for the U-channel is insuspended ceilings that contain lift-out ceiling panels. Inmodem construction, these lift-out panels provide readyaccess to mechanical and electrical equipment within thesuspended-ceiling area. Accordingly, it is important thatconduits installed in such an area do not prevent theremoval of panels or access to the area. Rod-suspendedU-channels provide the solution to conduit wiring in suchareas.

Sections of the U-channel and associated fittingsare available in aluminum or steel types. Another typeof material that can be used for supports is slotted-angle-steel units. Numerous prepunched slots allowinstallers to bolt on rods, straps, and similar materialwithout drilling holes. Slotted steel has unlimitedapplications in forming special structures, racks,braces. or similar items.

A cable-pulling kit (80149) has everything neededfor any wire or cable-pulling job. Most large PublicWorks and all battalions have the wire installation kit.The heavy-duty power wire/cable puller plugs into anyconvenient 115-volt source. It pulls 15 feet of cable perminute and can be used with various attachments foralmost any type of pulling job.

After a “fish” line has been blown or run throughthe conduit, a rope that is provided with the powercable puller can be pulled through the conduit. Thisrope. used with a cable grip, makes the actual pull. Thepower cable puller can be used in almost anyconfiguration. Figures 5-22 through 5-27 are examplesof the different setups.

SOLDERING AND SPLICINGPROCEDURES

As a CE project supervisor or crew leader, youneed to train your crew on the proper solderlessconnector splices, soldering splices, and tapingsplices. You will need to spot-check the connections toensure proper installation.

SOLDERLESS CONNECTORS

Solderless connectors (wire nuts) have almostcompletely eliminated soldering and taping for certaintypes of splices. They are designated to hold severalelectrical wires firmly together and provide an

Figure 5-22.—Pipe adapter to exposed conduit.

Figure 5-23.—Power unit to the power adapter.

insulating cover for the wires. They are available inseveral sizes. The size of the solderless connector isdetermined by the number and the size of the wires tobe joined.

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Figure 5-24.—“Up” pull, using exposed conduit.

SPLICES

An electrical splice is the joining of two or moreelectrical conductors by mechanically twisting themtogether or by using a special splicing device. Sincesplices can cause electrical problems, they must be madecarefully. Splices must be able to withstand anyreasonable mechanical strain that might be placed on theconnection. They also must allow electricity to passthrough as if the wire had never been broken. Some of themore common splices are explained below.

Figure 5-25.—“Down” pull, using exposed conduit.

Figure 5-26.—Pulling in an overhead pull box with the pullermounted independently for extra cable.

Figure 5-27.—Setup for ground pull.

Pigtail Splice

Because it is simple to make, the pigtail splice isprobably the most commonly used electrical splice.

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Figure 5-28 shows how to make a pigtail splice. Note thetwo ways to end the splice. When the splice is taped. theends must be bent back so the sharp edges will notpenetrate the tape (fig. 5-28). When a solderlessconnector is used instead of tape. the ends are cut off (fig.5-28). When more than two wires are joined in a pigtailsplice, as shown in figure 5-29, they should be twistedtogether securely before the solderless connector is put

Figure 5-28.—Simple pigtail splice.

Figure 5-29.—Multiple-wire pigtail splice.

on. Twisting the wires together first ensures that all thewires are fastened together properly.

Western Union Splice

The Western Union splice (fig. 5-30) is used whenthe connection must be strong enough to support longlengths of heavy, wire. In the past. this splice was usedto repair telegraph wires. If the splice is to be taped,care should be taken to eliminate any sharp edges fromthe wire ends.

T-tap

The T-tap (fig. 5-31) is a type of splice that allowsa connection to be made without cutting the main line.This connection is one of the most difficult to make. Acertain amount of practice may be necessary to makethis connection look neat. Study figure 5-3 1 todetermine the proper technique in making this splice.

Portable Cord Splices

Cord splices are weak because there is no connectorto hold them together; therefore. they should be used foremergency purposes only. If the cord must be saved, usetwist lock plugs and receptacles to rejoin the cord. Figure5-32 shows how solid wires are spliced. The individualsplices are staggered to prevent a large bump when thecord is taped. Additional strength may be added to thissplice by soldering each individual splice.

Figure 5-30.—Western Union splice used where substantialstrain may be placed on the connection.

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Figure 5-31.—T-tap used to connect into an ongoing line.

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Figure 5-32.—Portable cord splices.

Cable Splices

Large stranded cables (fig. 5-33) are not often usedin residential wiring; however, they are used in othersituations. such as for battery jumper cables andwelding cables. When jumper cables or welding cablesare broken, they can be temporarily repaired, as shownin figure 5-33.

Soldering Splices

Because solderless connectors (such as plastic endcaps) are time-saving and easy to use. the electrician nolonger needs to solder each and every splice. It not onlytakes less time to make a solderless connection but alsorequires less skill. However. soldering is still the mostreliable method of joining pieces of wire, and everyelectrician should learn how to solder.

Once the decision is made to solder an electricalsplice and the insulation has been stripped off the wire,the splice should be soldered as soon as possible. Thelonger the splice is exposed to dirt and air. the moreoxidation will occur thus lessening the chance of a goodsolder joint. Clean metal surfaces. free from oil. dirt. andrust (oxidation) are necessary to allow the melted solderto flow freely around the splice. The surfaces may becleaned by using light sandpaper or an emery cloth or byapplying flux to the joint asit is heated

Figure 5-33.—Gable splices.

Solder usually comes in either bar or wire form and ismelted with heat from soldering devices. such as asoldering iron. soldering gun. or propane torch (fig. 5-34).

The electric soldering iron and soldering gun areused when electrical service is available. The propanetorch is used to solder large wires or when there is noelectricity at the jobsite. Whatever method you use,be sure to apply solder on the side of the spliceopposite the point where you apply the heat. Figure5-35 shows the three methods of soldering. Themelting solder will flow toward the source of heat.Thus, if the top of the wire is hot enough to melt thesolder, the bottom of the wire closest to the heatsource will draw the solder down through all thewires. Allow the splice to cool naturally withoutmoving it. Do not blow on the joint or dip it in water tocool it. Rapid cooling will take all the strength out of asolder joint. Once it is cooled, clean off any excessflux with a damp rag, then dry and tape it.

WARNING

Avoid breathing the fumes and smoke fromhot solder. Some solder contains lead which ifinhaled or ingested can cause lead poisoning.Avoid prolonged skin contact with fluxes. Yoursupervisor will give you a Material Safety DataSheet (MSDS) with the precautions for solderand flux.

Taping Splices

Taping is required to protect the splice fromoxidation (formation of rust) and to insulate againstelectrical shock. Taping should provide at least asmuch insulation and mechanical protection for thesplice as the original covering. Although one wrap ofplastic (vinyl) tape will provide insulation protectionup to 600 volts, several wraps may be necessary toprovide good mechanical protection.

When plastic tape is used, it should be stretched asit is applied. Stretching will secure the tape morefirmly. Figures 5-36 through 5-39 show the mostcommonly used methods of taping splices.

ELECTRICAL SAFETY

Safety for the electrician today is far morecomplicated than it was 20 years ago. But with properuse of today’s safeguards and safety practices, workingon electrical equipment can be safe. Electricity must berespected. With common sense and safe workpractices, you can accomplish electrical work safely.

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Figure 5-34.—Sources of heat for soldering splices.

An electrician must know and be able to apply theprinciples of electricity safely. If you disregard your ownsafety, you also disregard the safety of your fellowworkers. Remember that the time to prevent an accidentis before it happens. Respect for electricity comes fromunderstanding electricity. Whenever in doubt, always askyour supervisor. Report any unsafe condition, unsafeequipment, or unsafe workpractices to your supervisor assoon as possible.

FUSES

Before removing any fuse from a circuit, be sure theswitch for that circuit is open or disconnected. Whenremoving fuses, use an approved type of fuse puller andbreak contact on the hot side of the circuit first. Whenreplacing fuses, install the fuse first into the load side ofthe fuse clip, then into the line side.

ELECTRICAL SHOCK

Electrical shock occurs when a person comes incontact with two conductors of a circuit or when his or herbody becomes part of the electrical circuit. In either case,

a severe shock can cause the heart and lungs to stopfunctioning. Also, because of the heat produced bycurrent flow, severe bums may occur where the currententers and exits the body.

Prevention is the best medicine for electrical shock.Respect all voltages and follow safe work procedures. Donot take chances. CEs, with the exception of very fewpersonnel with special training, are not qualified to workon live circuits.

PORTABLE ELECTRIC TOOLS

When using portable electric tools, always make surethey are in a safe operating condition. Make sure there is athird wire on the plug for grounding in case of shorts.Theoretically, if electric power tools are grounded and ifart insulation breakdown occurs, the fault current shouldflow through the third wire to ground instead of throughthe operator’s body to ground. Always use a ground-faultcircuit-interrupter (GFCI) with portable electric tools.New power tools are double insulated eliminating theneed for a ground prong; but for safety reasons, they stillshould be used with a GFCI.

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Figure 5-35.—Three methods of heating a solder joint.

OUT-OF-SERVICE PROTECTION

Before any repair is to be performed on a piece ofelectrical equipment, be absolutely certain the source ofelectricity is open and tagged or locked out of service.Whenever you leave your job for any reason or whenever

the job cannot be completed the same day. be sure thesource of electricity is still open or disconnected whenyou return to continue the work. Seabees have diedbecause they did not follow proper tag and lock-outprocedures. These procedures are a must. It takes time todo it, but it is worth your life.

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Figure 5-36.—Technique for taping a pigtail splice.

Figure 5-38.—Technique for taping a cord splice in anemergency only.

clothing and protective equipment requirements forworking around electricity.

Figure 5-37.—Technique for taping a Western Union splice.

SAFETY COLOR CODES

Federal law (OSHA) has established specific colorsto designate certain cautions and dangers. Table 5-6shows the accepted usage. Study these colors and becomefamiliar with all of them.

CLOTHING AND PERSONALPROTECTIVE EQUIPMENT

As a crew leader. you must be familiar with requiredsafety equipment and the conditions under which theequipment is to be used for your crew to perform anassigned task safely. The following is a list of common

Wear thick-soled work shoes for protection againsharp objects, such as nails. Wear work shoes withsafety toes if the job requires.

Wear electrically insulated gloves when there isthe slightest chance that you might come in contactwith energized parts.

Wear rubber boots in damp locations.

Wear safety goggles for protection againstairborne particles, electrical sparks, and acidsplashes.

Wear a hard hat. Wear an approved safety helmetwhen on a project site. Be careful to avoid placingyour head too near rotating machinery.

Wear gloves when handling sharp objects.

FIRE SAFETY

Fire safety should always be of great concern to youas a shop supervisor or leader. Furthermore, everymember of your crew should be concerned with firesafety. The following fire safety information will helpyou prevent or combat fires.

The chances of fire may be greatly decreased byfollowing rules of good housekeeping. Keep debris in adesignated area away from the building. Report to yoursupervisor any accumulations of rubbish or unsafeconditions that are a fire hazard.

If a fire should occur, however, the first thing to do isgive an alarm. All workers on the job should be alerted;the fire department should be called. In the time beforethe fire department arrives, a reasonable effort can bemade to contain the fire. In the case of some smaller fires,portable fire extinguishers that should be available at thesite can be used.

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Table 5-6.—OSHA Safety Color Codes

OSHA SAFETY COLOR CODES

Red Fire protection equipment and apparatus: portable containers offlammable liquids: emergency stop buttons; switches

YellowCaution and for marking physical hazards. waste containers forexplosive or combustible materials; caution against starting.using. or moving equipment under repair: identification of thestarting point or power source of machinery

Orange

Purple

Green

Dangerous parts of machines; safety start buttons; the exposedparts (edges) of pulleys, gears, rollers. cutting devices. and powerjaws

Radiation hazards

Safety; location of first aid equipment (other than fire fightingequipment)

Figure 5-39.—Technique for taping a solderless connector.

The following list gives the four common types offire. Each type of fire is designated by a class.

Class A fires occur in wood. clothing, paper,rubbish, and other such items. This type of fire usually canbe handled effectively with water. (Symbol: greentriangle.)

Class B fires occur with flammable liquids, such asgasoline, fuel oil, lube oil, grease, thinners, paints, and soforth. The agents required for extinguishing this type offire are those that will dilute or eliminate the air byblanketing the surface of the tire. Foam. CO2, and drychemicals are used. but not water. (Symbol: red square.)

Class C fires occur in electrical equipment andfacilities. The extinguishing agent for this type of fire mustbe a nonconductor of electricity and provide a smotheringeffect. CO2 and dry chemical extinguishers may be used,but not water. (Symbol: blue circle.)

Class D fires occur in combustible metals. such asmagnesium. potassium. powdered aluminum. zinc.

sodium, titanium, zirconium, and lithium. Theextinguishing agent for this type of fire must be a dry-powdered compound. The dry-powdered compound mustcreate a smothering effect. (Symbol: yellow star.)

Figure 5-40 shows the symbols that are associatedwith the four classes. One or more of these symbolsshould appear on each extinguisher. Because all fireextinguishers cannot be used on all types of fires, theelectrician should be aware of how to identify which fireextinguisher should be used.

Always read the operator’s instructions beforeusing an extinguisher. Also, never use water againstelectrical or chemical fires. Water also should not beused against gasoline, fuel, or paint fires, as it mayhave little effect and only spread the fire. Figure 5-41shows some common fire extinguishers and theiruses.

Fire extinguishers are normally red. If they are notred, they should have a red background so they can beeasily located.

If the tire department is called, be ready to directthem to the fire. Also, inform them of any specialproblems or conditions that exist, such as downedelectrical wires or leaks in gas lines.

In this chapter we have discussed various aspects ofinterior wiring (above and below grade), bendingconduit. conduit support and installation. soldering andsplicing, and electrical and fire safety. Each of these areaswas briefly discussed and reference given to where youcould find additional specific information. To understandthe material discussed, you must study these references.

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Figure 5-40.—Fire extinguisher markings and capabilities.

Figure 5-41.—Selection of an effective and safe fire extinguisher.

The following listed handbooks are excellent examples American Electrician’s Handbook by Terrell Croftof references for further study. and Wilford I. Summers.

Standard Handbook for Electrical Engineers by National Electrical Code® by the National FireDonald G. Fink and H. Wayne Beaty. Protection Agency.

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CHAPTER 6

FIBER OPTICS AND LIGHTING SYSTEMS

INTRODUCTION

This chapter will expand on the information youlearned in the CE Basic TRAMAN on fiber optics andarea lighting and also introduce you to airfield lightingsystems.

FIBER OPTICS

The CE Basic TRAMAN taught you that a fiber-optic data link had three basic functions:

To convert an electrical input signal to an opticalsignal

To send the optical signal over an optical fiber

To convert the optical signal back to an electricalsignal

The fiber-optic data link converts an electricalsignal into an optical signal, permitting the transfer ofdata along an optical fiber. The fiber-optic deviceresponsible for that signal conversion is a fiber-optictransmitter.A fiber-optic transmitter is a hybriddevice. The transmitter converts electrical signals intooptical signals and launches the optical signals into anoptical fiber. A fiber-optic transmitter consists of aninterface circuit, a source drive circuit, and anoptical source.

The interface circuit accepts the incomingelectrical signal and processes it to make it compatiblewith the source drive circuit. The source drive circuitintensity modulates the optical source by varying thecurrent through the source. An optical source convertselectrical energy (current) into optical energy (light).Light emitted by an optical source is launched, orcoupled, into an optical fiber for transmission.

Fiber-optic data link performance depends on theamount of optical power (light) launched into theoptical fiber. This chapter provides an overview ofoptical sources and fiber optic transmitters.

OPTICAL SOURCE PROPERTIES

The development of efficient semiconductoroptical sources, along with low-loss optical fibers, hasled to substantial improvements in fiber-optic

communications. Semiconductor optical sources havethe physical characteristics and performanceproperties necessary for successful implementationsof fiber-optic systems. Optical sources should do thefollowing:

Be compatible in size to low-loss optical fibersby having a small light-emitting area capable oflaunching light into fiber.

Launch sufficient optical power into the opticalfiber to overcome fiber attenuation and connectionlosses, allowing for signal detection at the receiver.

Emit light at wavelengths that minimize opticalfiber loss and dispersion. Optical sources should have anarrow spectral width to minimize dispersion.

Allow for direct modulation of optical outputpower.

Maintain stable operation in changingenvironmental conditions (such as temperature).

Cost less and be more reliable than electricaldevices, thereby permitting fiber-optic communicationsystems to compete with conventional systems.

Semiconductor optical sources suitable for fiber-optic systems range from inexpensive light-emittingdiodes (LEDs) to more expensive semiconductorlasers. Semiconductor LEDs and laser diodes (LDs)are the principal light sources used in fiber optics.

SEMICONDUCTOR LIGHT-EMITTINGDIODES AND LASER DIODES

Semiconductor LEDs emit incoherent light.Spontaneous emission of light in semiconductor LEDsproduces light waves that lack a fixed-phaserelationship. Light waves that lack a fixed-phaserelationship are referred to as incoherent light. LEDsare the preferred optical source for multimode systemsbecause they can launch sufficient power at a lowercost than semiconductor laser diodes (LDs).

Semiconductor LDs emit coherent light. Lightwaves having a fixed-phase relationship are referred toas coherent light. Since semiconductor LDs emit morefocused light than LEDs, they are able to launch optical

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power into both single mode and multimode opticalfibers; however. LDs usually are used only in singlemode fiber systems because they require morecomplex driver circuitry and cost more than LEDs.

Optical power produced by optical sources canrange from microwatts (µ W) for LEDs to tens ofmilliwatts (µ W) for semiconductor LDs; however, itis not possible to couple all the available optical powereffectively into the optical fiber for transmission.

The amount of optical power coupled into the fiberis the relevant optical power. It depends on thefollowing factors:

The angles over which the light is emitted

The size of the light-emitting area of the sourcerelative to the fiber core size

The alignment of the source and fiber

The coupling characteristics of the fiber

Typically, semiconductor lasers emit light spreadout over an angle of 10 to 15 degrees. SemiconductorLEDs emit light spread out at even larger angles.Coupling losses of several decibels (dB) can easilyoccur when coupling light from an optical source to afiber, especially with LEDs.

SEMICONDUCTOR MATERIAL

Understanding optical emission in semiconductorlasers and LEDs requires knowledge of semiconductormaterial and device properties. Providing a completedescription of semiconductor properties is beyond thescope of this text. In this chapter we will only discussthe general properties of semiconductor LEDs andLDs.

Semiconductor sources are diodes, with all of thecharacteristics typical of diodes; however, theirconstruction includes a special layer, called the activelayer, that emits photons (light particles) when acurrent passes through the layer. The particularproperties of the semiconductor are determined by thematerials used and the layering of the materials withinthe semiconductor. Silicon (Si) and gallium arsenide(GaAs) are the two most common semiconductormaterials used in electronic and electro-optic devices.In some cases, other elements, such as aluminum (Al),indium (In), and phosphorus (P), are added to the basesemiconductor material to modify the semiconductorproperties. These elements are called dopants. Currentflowing through a semiconductor optical sourcecauses it to produce light.

LEDs general ly produce l ight throughspontaneous emission when a current is passedthrough them. Spontaneous emission is the randomgeneration of photons within the active layer of theLED. The emitted photons move in random directions.Only a certain percentage of the photons exit thesemiconductor and are coupled into the fiber. Many ofthe photons are absorbed by the LED materials and theenergy is dissipated as heat. This process causes thelight output from a LED to be incoherent, have a broadspectral width. and have a wide output pattern.

Laser diodes are much more complex than LEDs.Laser is an acronym for Light Amplification by theStimulated Emission of Radiation. Laser diodes pro-duce light through stimulated emission when a currentis passed through them. Stimulated emissiondescribes how light is produced in any type of laser. Inthe laser diode, photons, initially produced by, spon-taneous emission, interact with the laser material toproduce additional photons. This process occurs with-in the active area of the diode called the laser cavity.

As with the LED, not all of the photons producedare emitted from the laser diode. Some of the photonsare absorbed and the energy dissipated as heat. Theemission process and the physical characteristics ofthe diode cause the light output to be coherent, have anarrow spectral width. and have a narrow outputpattern.

It is important to note that in both LED and laserdiodes all of the electrical energy is not converted intooptical energy. A substantial portion is converted toheat. Different LED and laser diode structures convertdifferent amounts of electrical energy into opticalenergy.

FIBER-OPTIC TRANSMITTERS

As stated previously, a fiber-optic transmitter is ahybrid electro-optic device. It converts electricalsignals into optical signals and launches the opticalsignals into an optical fiber. A fiber-optic transmitterconsists of an interface circuit, a source drive circuit,and an optical source. The interface circuit accepts theincoming electrical signal and processes it to make itcompatible with the source drive circuit. The sourcedrive circuit intensity modulates the optical source byvarying the current through it. The optical signal iscoupled into an optical fiber through the transmitteroutput interface.

Although semiconductor LEDs and LDs havemany similarities. unique transmitter designs result

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from differences between LED and LD sources.Transmitter designs compensate for differences inoptical output power, response time, linearity, andthermal behavior between LEDs and LDs to ensureproper system operation. Fiber-optic transmittersusing LDs require more complex circuitry thantransmitters using LEDs.

Transmitter output interfaces generally fall intotwo categories: optical connectors and optical fiberpigtails (fig. 6-1). Optical pigtails are attached to thetransmitter optical source. This pigtail is generallyrouted out of the transmitter package as a coated fiberin a loose buffer tube or a single fiber cable. The pigtailis either soldered or epoxied to the transmitter packageto provide fiber strain relief. The buffer tube or singlefiber cable also is attached to the transmitter package toprovide additional strain relief.

The transmitter output interface may consist of afiber-optical connector. The optical source maycouple to the output optical connector through anintermediate optical fiber. One end of the optical fiberis attached to the source. The other end terminates in

Figure 6-1.—Pigtailed and connectorized fiber-optic devices.

the transmitter optical output connector. The opticalsource also may couple to the output optical connectorwithout an intermediate optical fiber. The opticalsource is placed within the transmitter package tolaunch power directly into the fiber of the matingoptical connector. In some cases, lenses are used tomore efficiently couple light from the source into themating optical connector.

OPTICAL DETECTORS AND FIBER-OPTIC RECEIVERS

A fiber-optic transmitter is an electro-optic devicecapable of accepting electrical signals, convertingthem into optical signals, and launching the opticalsignals into an optical fiber. The optical signalspropagating in the fiber become weakened anddistorted because of scattering, absorption, anddispersion. The fiber-optic device responsible forconverting the weakened and distorted optical signalback to an electrical signal is a fiber-optic receiver.

A fiber-optic receiver is an electro-optic devicethat accepts optical signals from an optical fiber andconverts them into electrical signals. A typical fiber-optic receiver consists of an optical detector, a low-noise amplifier, and other circuitry used to produce theoutput electrical signal (fig. 6-2). The optical detectorconverts the incoming optical signal into an electricalsignal. The amplifier then amplifies the electricalsignal to a level suitable for further signal processing.The type of other circuitry contained within thereceiver depends on what type of modulation is usedand the receiver’s electrical output requirements.

A transducer is a device that converts inputenergy of one form into output energy of another. Anoptical detector is a transducer that converts anoptical signal into an electrical signal. It does this bygenerating an electrical current proportional to the

Figure 6-2.—Block diagram of a typical fiber-optic receiver.

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intensity of incident optical radiation. The relationshipbetween the input optical radiation and the outputelectrical current is given by the detector responsivity.

FIBER-OPTIC SYSTEM TOPOLOGY

Most of the discussion on fiber-optic data linksprovided earlier in this chapter and in the CE BasicTRAMAN refers to simple point-to-point links. Apoint-to-point fiber-optic data link consists of anoptical transmitter, an optical fiber, and an opticalreceiver. In addition. any splices or connectors used tojoin individual optical fiber sections to each other andto the transmitter and the receiver are included. Figure6-3 provides a schematic diagram of a point-to-pointfiber-optic data link.

A common fiber-optic application is the fullduplex link. This link consists of two simple point-to-point links. The links transmit in opposite directionsbetween the equipment. This application may beconfigured using only one fiber. If configured with onefiber. fiber-optic splitters are used at each end to couplethe transmit signal onto the fiber and receive signals tothe detector.

All fiber-optic systems are simply sets of point-to-point fiber-optic links. Different system topologiesarise from the different ways that point-to-point fiber-optic links can be connected between equipment. Theterm topology, as used here, refers to the configurationof various types of equipment and the fiber--opticcomponents interconnecting them. This equipmentmay be computers, workstations, consoles, or otherequipment. Point-to-point links are connected toproduce systems with linear bus, ring, star, or treetopologies. Point-to-point fiber-optic links are thebasic building block of all fiber-optic systems.

SYSTEM INSTALLATION

The Navy has a standard to provide detailedinformation and guidance to personnel concerned withthe installation of fiber-optic cables and cable plants.The fiber-optic cable plant consists of all the fiber-

optic cables and the fiber-optic interconnectionequipment, including connectors, splices, andinterconnection boxes. The fiber-optic cable and cableplant installation standard consists of the following:

Detailed methods for cable storage andhandling, end sealing, repair, and splicing

Detailed methods for fiber-optic equipmentinstallation and cable entrance to equipment

Detailed methods to install fiber-optic cables incableways

Detailed methods for installing fiber-opticconnectors and other interconnections, such assplices

Detailed methods for testing fiber-optic cableplants before, during, and after installation andrepair

There are other standards that discuss fiber-opticsystem installation. Many of these standards incor-porate procedures for repair, maintenance, and testing.The techniques developed for installing fiber-optichardware are not much different than for installinghardware for copper-based systems: however. theprimary precautions that need to be emphasized wheninstalling fiber-optic systems are as follows:

Optical fibers or cables should never be bent at aradius of curvature less than a certain value, called theminimum bend radius. Bending an optical fiber orcable at a radius smaller than the minimum bend radiuscauses signal loss.

Fiber-optic cables should never be pulled tight orfastened over or through sharp comers or cutting edges.Extremely sharp bends increase the fiber loss and maylead to fiber breakage.

Fiber-optic connectors should always be cleanedbefore mating. Dirt in a fiber-optic connection willsignificantly increase the connection loss and maydamage the connector.

Precautions must be taken so the cable does notbecome kinked or crushed during installation of the

Figure 6-3.—A schematic diagram of a point-to-point fiber-optic data link.

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hardware. Extremely sharp kinks or bends increase thefiber loss and may lead to fiber breakage.

FIBER-OPTIC MEASUREMENTS

Fiber-optic data links operate reliably if fiber-optic component manufacturers and you perform thenecessary laboratory and field measurements. Manu-facturers must test how component designs, materialproperties, and fabrication techniques affect theperformance of fiber-optic components. These testscan be categorized as design tests or quality controltests. Design tests are conducted during the develop-ment of a component. Design tests characterize theperformance of the component (optical, mechanical,and environmental) in the intended application. Oncethe performance of the component is characterized, themanufacturer generally only conducts quality controltests. Quality control tests verify that the parts pro-duced are the same as the parts the design tests wereconducted on. When manufacturers ship fiber-opticcomponents, they provide quality control data detail-ing the results of measurements performed during orafter fabrication of the component.

You, as the installer, should measure some of theseparameters upon receipt before installing thecomponent into the fiber-optic data link. These testsdetermine if the component has been damaged in theshipping process. In addition, you should measuresome component parameters after installing or repair-ing fiber-optic components in the field. The valuesobtained can be compared to the system installationspecifications. These measurements determine if theinstallation or repair process has degraded per-formance of the component and will affect data linkoperation.

FIELD MEASUREMENTS

Field measurements measure the transmissionproperties of installed fiber-optic components. Youmust perform field measurements to evaluate thoseproperties most likely affected by the installation orrepair of fiber-optic components or systems.

The discussion on field measurements is limited tooptical fiber and optical connection properties. Opticalfiber and optical connection field measurementsevaluate only the transmission properties affected bycomponent or system installation or repair. Becauseoptical fiber geometrical properties, such as core andcladding diameter and numerical aperture, are notexpected to change, there is no need to remeasure these

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properties. The optical connection properties that arelikely to change are connection insertion loss andreflectance and return loss.

Field measurements require rugged, portable testequipment, unlike the sophisticated test equipmentused in the laboratory. Field test equipment must pro-vide accurate measurements in extreme environmentalconditions. Since electrical power sources may notalways be available in the field, test equipment shouldallow battery operation. In addition, while both fiberends are available for conducting laboratorymeasurements, only one fiber end may be readilyavailable for field measurements. Even if both fiberends are available for field measurements, the fiberends are normally located some distance apart, therebyrequiring two people to perform the measurements.

The main field measurement technique involvesoptical time domain reflectometry. An optical timedomain reflectometer (OTDR) is recommended forconducting field measurements on installed opticalfibers or links of 50 meters or more in length. AnOTDR requires access to only one fiber end. An OTDRmeasures the attenuation of installed optical fibers as afunction of length. It also identifies and evaluatesoptical connection losses along a cable link and locatesany fiber breaks or faults.

Users also can measure fiber attenuation and cableplant transmission loss, using an optical power meterand a stabilized light source. Use this measurementtechnique when optical time domain reflectometry isnot recommended. Measurements obtained with astabilized light source and power meter are more accu-rate than those obtained with an OTDR. Measuringfiber attenuation and transmission loss using a powermeter and light source requires access to both ends ofthe fiber or link. An optical loss test set (OLTS)combines the power meter and source functions intoone physical unit.

OPTICAL TIME DOMAINREFLECTOMETRY

You use optical time domain reflectometry tocharacterize optical fiber and optical connection pro-perties in the field. In optical time domainreflectometry, an OTDR transmits an optical pulsethrough an installed optical fiber. The OTDR measuresthe fraction of light that is reflected back. When youcompare the amount of light scattered back at differenttimes, the OTDR can determine fiber and connectionlosses, When several fibers are connected to form an

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installed cable plant, the OTDR can characterizeoptical fiber and optical connection properties alongthe entire length of the cable plant. A fiber-opticcable plant consists of optical fiber cables,connectors, splices, mounting panels, jumper cables,and other passive components. A cable plant does notinclude active components, such as opticaltransmitters or receivers.

The OTDR displays the backscattered andreflected optical signal as a function of length. TheOTDR plots half the power in decibels (dB) versushalf the distance. Plotting half the power in dB andhalf the distance corrects for round-trip effects. Byanalyzing the OTDR plot, or trace, you can measurefiber attenuation and transmission loss between anytwo points along the cable plant. You also can measureinsertion loss and reflectance of any opticalconnection. In addition, you use the OTDR trace tolocate fiber breaks or faults. Figure 6-4 shows anexample OTDR trace of an installed cable plant.

MECHANICAL AND FUSION SPLICES

Mechanical splicing involves using mechanicalfixtures to align and connect optical fibers.Mechanical splicing methods may involve eitherpassive or active core alignment. Active corealignment produces a lower loss splice than passivealignment; however, passive core alignment methods

can produce mechanical splices with acceptable lossmeasurements even with single mode fibers.

In the strictest sense, a mechanical splice is apermanent connection made between two opticalfibers. Mechanical splices hold the two optical fibersin alignment for an indefinite period of time withoutmovement. The amount of splice loss is stable overtime and unaffected by changes in environmental ormechanical conditions.

The types of mechanical splices that exist formechanical splicing include glass, plastic, metal, andceramic tubes; also included are V-groove, and rotarydevices: Materials that assist mechanical splices insplicing fibers include transparent adhesives and indexmatching gels. Transparent adhesives are epoxyresins that seal mechanical splices and provide indexmatching between the connected fibers.

GLASS OR CERAMIC ALIGNMENT TUBESPLICES

Mechanical splicing may involve the use of a glassor ceramic alignment tube or capillary. The innerdiameter of this glass or ceramic tube is only slightlylarger than the outer diameter of the fiber. Atransparent adhesive, injected into the tube, bonds thetwo fibers together. The adhesive also provides indexmatching between the optical fibers. Figure 6-5illustrates fiber alignment using a glass or ceramictube. This splicing technique relies on the inner

Figure 6-4.—OTDR trace of an installed cable plant.

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Figure 6-5.—A glass or ceramic alignment tube for mechanical splicing.

diameter of the alignment tube. If the inner diameter istoo large, splice loss will increase because of fibermisalignment. If the inner diameter is too small, it isimpossible to insert the fiber into the tube.

V-GROOVED SPLICES

Mechanical splices also may use either a groovedsubstrate or positioning rods to form suitableV-grooves for mechanical splicing. The basicV-grooved device relies on an open-grooved substrateto perform fiber alignment. When you are inserting thefibers into the grooved substrate, the V-groove alignsthe cladding surface of each fiber end. A transparentadhesive makes the splice permanent by securing thefiber ends to the grooved substrate. Figure 6-6illustrates this type of open V-grooved splice.

V-grooved splices may involve sandwichingthe butted ends of two prepared fibers between aV-grooved substrate and a flat, glass plate.Additional V-grooved devices use two or threepositioning rods to form a suitable V-groove forsplicing. The V-grooved device that uses two pois-tioning rods is the spring V-grooved splice. Thissplice uses a groove formed by two rods positionedin a bracket to align the fiber ends. The diameter ofthe positioning rods permits the outer surface ofeach fiber end to extend above the groove formedby the rods. A flat spring presses the fiber ends intothe groove maintaining fiber alignment. Trans-parent adhesive completes the assembly processby bonding the fiber ends and providing indexmatching. Figure 6-7 is an illustration of thespring V-grooved splice. A variation of this splice

Figure 6-6.—Open V-grooved splice.

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Figure 6-7.—Spring V-grooved mechanical splice.

uses a third positioning rod instead of a flat spring. Therods are held in place by a heat-shrinkable band ortube.

ROTARY SPLICES

In a rotary splice, the fibers are mounted into aglass ferrule and secured with adhesives. The splicebegins as one long, glass ferrule that is broken in halfduring the assembly process. A fiber is inserted intoeach half of the tube and epoxied in place, using anultraviolet cure epoxy. The end face of the tubes is thenpolished and placed together, using the alignmentsleeve. Figure 6-8 is an illustration of a rotarymechanical splice. The fiber ends retain their originalorientation and have added mechanical stability sinceeach fiber is mounted into a glass ferrule and alignmentsleeve. The rotary splice may use index matching gelwithin the alignment sleeve to produce low-losssplices.

FUSION SPLICES

The process of fusion splicing involves usinglocalized heat to melt or fuse the ends of two opticalfibers together. The splicing process begins bypreparing each fiber end for fusion. Fusion splicingrequires that all protective coatings be removed fromthe ends of each fiber. The fiber is then cleaved, usingthe score-and-break method. The quality of each fiberend is inspected with a microscope. In fusion splicing,

Figure 6-8.—Rotary mechanical splice.

splice loss is a direct function of the angles and qualityof the two fiber end faces.

The basic fusion-splicing apparatus consists oftwo fixtures on which the fibers are mounted and twoelectrodes. Figure 6-9 shows a basic fusion-splicingapparatus. An inspection microscope assists in theplacement of the prepared fiber ends into a fusion-splicing apparatus. The fibers are placed into theapparatus, aligned, and then fused together. Initially,fusion splicing used nichrome wire as the heatingelement to melt or fuse fibers together. New fusion-splicing techniques have replaced the nichrome wirewith carbon dioxide (CO2) lasers, electric arcs, or gasflames to heat the fiber ends, causing them to fusetogether. The small size of the fusion splice and thedevelopment of automated fusion-splicing machineshave made electric arc fusion (arc fusion) one of themost popular splicing techniques.

MULTIFIBER SPLICES

Normally, multifiber splices are only installed onribbon type of fiber-optic cables. Multifiber splicingtechniques can use arc fusion to restore connection, butmost splicing techniques use mechanical splicingmethods. The most common mechanical splice is theribbon splice.

A ribbon splice uses an etched silicon chip, orgrooved substrate, to splice the multiple fiberswithin a flat ribbon. The spacing between the etchedgrooves of the silicon chip is equal to the spacingbetween the fibers in the flat ribbon. Before youplace each ribbon on the etched silicon chip, eachfiber within the ribbon cable is cleaved. All of thefibers are placed into the grooves and held in placewith a flat cover. Typically, an index matching gel isused to reduce the splice loss. Figure 6-10 shows theplacement of the fiber ribbon on the etched siliconchip.

Figure 6-9.—A basic fusion-splicing apparatus.

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Figure 6-10.—Ribbon splice on etched silicon chip.

AREA LIGHTING SYSTEMS LIGHTING INTENSITY

Streetlighting at naval facilities usually need notproduce as high a level of illumination as that requiredin many municipal areas. Because night activity byvehicles and pedestrians is low, only enough light issupplied to permit personnel to identify streets andbuildings and to furnish sufficient visibility for localsecurity requirements. Requirements for security andfloodlighting systems will depend on the situation andthe areas to be protected or illuminated.

The illumination and uniformity requirements aregiven in table 6-1. Note that the illumination level isdependent upon the roadway classification and thearea classification that are defined in the followingmaterial.

Streets are classified into three major categories:major, collector, and local.

STREET AND AREA CLASSIFICATION

Major: The part of the roadway system thatserves as the principal network for through traffic flow.The routes connect areas of principal traffic generationand important rural highways entering the city.

Streetlighting requirements generally consist of aminimum average maintained footcandle level and amaximum allowable uniformity ratio for the instal-lation. The authority for these requirements is theAmer ican Na t iona l S tandards Ins t i t u te(ANSI)/Illuminating Engineering Society (IES)publication, Standard Practice for Roadway Lighting.Another publication that may prove helpful isInformational Guide for Roadway Lighting, publishedby the American Association of State Highway andTransportation Officials. The only significant dif-ference between the two publications is that the latterallows a 4 to 1 uniformity ratio instead of the 3 to 1uniformity ratio specified by IES. These uniformityratios are defined as the ratio of the average footcandlevalue divided by the minimum footcandle value.

Collector: Distributor and collector roadwaysserving traffic between major and local roadways.These are roadways used mainly for traffic movementswithin residential, commercial, and industrial areas

Local: Roadways used primarily for directaccess to residential, commercial, industrial, or otherabutting property. They do not include roadwayscarrying through traffic.

The locality or area is also defined by three majorcategories: commercial, intermediate, and residential.

Commercial: That portion of a municipality in abusiness development where ordinarily there are largenumbers of pedestrians and a heavy demand for parkingspace during periods of peak traffic or a sustained high

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Table 6-1.—Roadway Illumination and Lamp Selection Guide.

Area Class Roadways Min. Average. Uniformity

Classification Maint. FC Avg./Min.FC/FC

Local 0.4 6:l

Residential Collector 0.6 3:l

Major 1.0 3:1

Intermediate

Local

Collector

Major

0.6 3:l

0.9 3:l

1.4 3:l

Commercial Collector 1.2 3:l

Major 2.0 3:l

pedestrian volume and a continuously heavy demandfor off-street parking during business hours.

Intermediate: That portion of a municipalitywhich is outside of a downtown area but generallywithin the zone of influence of a business or industrialdevelopment; characterized often by a moderatelyheavy nighttime pedestrian traffic and a somewhatlower parking turnover than is found in a commercialarea. This definition includes military installations,hospitals, and neighborhood recreational centers.

Residential: A residential development, or amixture of residential and commercial establishments,characterized by few pedestrians and a lower parkingdemand or turnover at night. This definition includesareas with single-family homes and apartments.

SELECTION OF LUMINAIRES

Luminaries are designed to provide lighting to fitmany conditions. For street and area lighting, fivebasic patterns are available, as shown in figure 6-11.While many luminaries can be adjusted to producemore than one pattern, no luminaire is suitable for allpatterns. Care must be used, especially in repair andreplacement, to install the proper luminaire for thedesired pattern, as specified in the manufacturer’sliterature. Even when the proper luminaire is installed,care must be used to ensure that all adjustments havebeen properly made to produce the desired results.

Type I (fig. 6-11a) is intended for narrowroadways with a width about equal to lamp-mounting

height. The lamp should be near the center of the street.A variation of this positioning (fig. 6-11b) is suitable forintersections of two such roadways with the lamp at theapproximate center.

Type II (fig. 6-11c) produces more spread thandoes Type I. It is intended for roadways with a width ofabout 1.6 times the lamp-mounting height with the lamplocated near one side. A variation (fig. 6-11d) is suitablefor intersections of two such roadways with the lampnot near the center of the intersection.

Type III (fig. 6-11e) is intended for luminarieslocated near the side of the roadway with a width of notover 2.7 times the mounting height.

Type IV (fig. 6-11f) is intended for side-of-roadmounting on a roadway with a width of up to 3.7 timesthe mounting height.

Type V (fig. 6-11g) has circular distribution andis suitable for area lighting and wide roadwayintersections. Types III and IV can be staggered onopposite sides of the roadway for better uniformity inlighting level or for use on wider roadways.

MOUNTING HEIGHT AND SPACING

There are two standards for determining apreferred luminaire mounting height: the desirabilityof minimizing direct glare from the luminaire and theneed for a reasonably uniform distribution ofillumination on the street surface. The higher theluminaire is mounted, the farther it is above the normal

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Figure 6-11.—Light distribution patterns for roadway lighting.

line of vision and the less glare it creates. Greatermounting heights may often be preferable, butheights less than 20 feet cannot be considered goodpractice.

You must be somewhat familiar with theterminology relating to how fixtures are locateddown a roadway. Figure 6-12 shows theserelationships graphically. The followinginformation will be useful when determining themost appropriate mounting arrangements:

The “transverse direction” is defined as backand forth across the width of the road, and the“longitudinal direction” is defined as up and down thelength of the road.

Modern roadway fixtures are designed to bemounted in the vicinity of one of the curbs of the road.

The “overhang” is defined as the dimension between thecurb behind the fixture and a point directly beneath thefixture.

A luminaire overhang should not exceed 25percent of the mounting height.

No attempt should be made to light a roadwaythat is more than twice the width of the fixture-mounting height. A roadway luminaire produces abeam in both longitudinal directions and is limited in itsability to light across the street.

There are three ways that a luminaire may bepositioned longitudinally down the roadway (fig. 6-12).Note that the spacing is always the dimension from onefixture to the next down the street regardless of whichside of the street the fixture is located.

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Figure 6-12.—Luminaire arrangement and spacing.

A staggered arrangement generates betteruniformity and possibly greater spacing than a one-sidearrangement. That is particularly true when the width ofthe road becomes significantly greater than themounting height. When the width of the road startsapproaching two mounting heights, an oppositearrangement definitely should be considered. Thatwould, in effect, extend the two-mounting-height widthlimitation out to four-mounting heights.

The classification of a road and the correspondingillumination levels desired influences the spacingbetween luminaries. On a residential road, it may bepermissible to extend the spacing so that the lightbeams barely meet (fig. 6-13). For traffic on businessroadways where uniformity of illumination is moreimportant, it may be desirable to narrow the spacing toprovide 50-to 100-percent overlap.

MANUFACTURER’S LITERATURE

The performance specifications of each model,type, and size of luminaire are provided with the

fixture or obtained from the manufacturer’s orderinginformation. A working knowledge of this informationwill assist you in selecting and installing the correctluminaire to accomplish the job. Manufacturersprovide technical literature for every luminaire theymake. This literature includes utilization and isofootcandle curves. These curves are important incalculating the lighting intensity of a particularlumunaire. Figure 6-14 is a sample of manufacturer’sliterature for a 250- or 400-watt light fixture.

Utilization Curve

The utilization curve (fig. 6-14A), a measure ofluminaire efficiency, shows the amount of light thatfalls on the roadway and adjacent areas. The amount oflight that is usable or actually falls on the area to belighted is plotted as a percentage of the total lightgenerated in the luminaire for various ratios oftransverse distance (across the street from theluminaire on both the house side and street side) to themounting height (fig. 6-15). The coefficient of

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Figure 6-13.—Pavement brightness.

utilization for any specific situation is obtained fromthis curve. The utilization curve will determine theamount of light that actually strikes the roadwaysurface. This percentage of light has an impact on thespacing distance of the luminaries.

elevation. Thus, at any point on the diagram (orroadway), we know the magnitude and direction of theillumination with respect to nearby points. To makethis data more universal, you are given both the tophorizontal and left vertical axes in terms of mounting-height ratios.

Isofootcandle Curve It is sometimes convenient for you to replot the

The isofootcandle diagram (fig. 6-14B) shows the isofootcandle data to the same scale as that used on a

distribution of illumination on the road surface in thedrawing containing a lighting layout. By

vicinity of the luminaire.superimposing this diagram, you can study thedistribution of light. Under the unity correction factor

The lines on this diagram connect all points having in the mounting-height table (fig. 6-14B), one can findequal illumination, much as the contour lines on athe mounting height for which the data are calculated.topographical map indicate all points having the sameThe numbers beside each line represent the initial

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Figure 6-14.—Streetlight manufacturer’s literature.

footcandle values per 1,000 lamp lumens. EachMaintenance Factorfootcandle value must be multiplied by 50 to obtain thecorrect footcandle value on the isofootcandle diagram. Lighting efficiency is seriously impaired by

This ratio of actual lamp lumens divided by 1,000 is blackened lamps, by lamp life, and by dirt on the

known as the lamp factor (LF). Note that the lamp reflecting surfaces of the luminaire. Tocompensate

factor allows a curve to represent the distribution from for the gradual loss of illumination, you must applymore than one lamp wattage; for example, from 250-a maintenance factor (MF) to the lightingand 400-watt lamps. calculations.

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Figure 6-15.—Luminaire utilization.

Normally, each luminaire manufacturer cansupply you with the maintenance factor for your lampmodel; however, when the manufacturer’s informationis not available, a 0.70 maintenance factor is widelyused in the industry.

LIGHTING INTENSITY CALCULATIONS

Achieving the most satisfactory solution for anygiven lighting problem requires sound judgment inmaking necessary compromises of all factorsinvolved.

Selection of the luminaire can be influenced bybudget constraints, present stock levels in the FederalSupply System, and availability. Once the luminaire isselected, it is important that you use the manufacturer’s

literature to determine the number of luminaries,mounting height, and spacing required to produce thedesired illumination intensity.

Using the manufacturer’s literature supplied infigure 6-14, let us solve this sample problem:

Find:

1.

2.

One-sided spacing required to provide specifiedillumination

Uniformity of illumination

Given: (fig. 6-16)

Street width, 50 feet

Mounting height, 40 feet

Pole setback from curb, 2 feet

Figure 6-16.—Streetlight sample problem.

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Bracket length, 12 feet

Required average maintained level ofillumination, 2 footcandles

400-watt luminaire (50,000 lamp lumens)

Solution:

1. Spacing. The equation to determine correctspacing is

Spacing (S) =(LL)(MF)(CU)

(fc)(W)

Where:

LL =

MF =

CU =

fc =

W =

rated initial lamp lumens

maintenance factor

coefficient of utilization

illumination in footcandles

street width. curb to curb

The values are given for LL (50.000), MF (assume0.70). W (50). and fc (2). After a value for CU isdetermined, you can solve the equation for averagespacing.

To determine the coefficient of utilization,calculate the amount of wasted light on the street side(SS) and the house side (HS) where:

Ratio of HS =Transverse Distance 10= =0.25

Mounting Height 40

50-10 40Ratio of SS=

Transversel Distance= =1.0Mounting Height 40 40

From the utilization curve in figure 6-17, the ratioof 1.0, street side,corresponds to 40 percent. and theratio of 0.25, house side, corresponds to3 percent. for atotal of 43 percent CU.

Spacing can be determined as

S = (50,000) (0.70) (0.43)= 150 feet.(2)(50)

2. Uniformity.

The uniformity of illumination is expressed interms of a ratio of

Average fcMinimum fc

It has been determined that one-side spacing of150 feet will produce an average of 2 footcandles onthe roadway surface. The point of minimumillumination can now be determined from theisofootcandle diagram.

The minimum value of the illumination can befound by studying the isofootcandle diagram and tak-ing into account all luminaries that are contributingsignificant amounts of light. Generally, the minimumvalue will be found along a line halfway, between twoconsecutively spaced luminaries. The minimum valuecan be determined by. checking the minimum foot-candle values at points P1, P2, and P3. as shown infigure 6-18.

The roadway surface can be plotted on theisofootcandle curve by observing the 40-footmounting height to longitudinal and transversedistance ratios. (See fig. 6-19.) Since PI is locatedoutside the 0.02 footcandle line. it is the lowest totalfootcandle value. This value would be 0.03 fc (0.015footcandle from each luminaire).

Figure 6-20 shows a perspective view of the twoisofootcandle lines that are considered whendetermining the illumination value at P1.

The following factors are now applied to this“raw” footcandle value, as shown in the formula:

fc min = (fc) (LF) (MF) (CF)

Where:

fc min = minimum point footcandles

fc = raw footcandle from isofootcandlediagram

LF = lamp factor

MF = maintenance factor

CF = mounting height correction factor

The values are given for fc (0.03) and MF (assume0.70). The value for LF was determined earlier as 50for the 400-watt lamp. The CF factor can bedetermined from the correction chart below theisofootcandle curve in figure 6-14. The CF for a 40-foot mounting height is 0.56.

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Figure 6-17.—Utilization curve

FLOODLIGHTS

Streetlighting systems usually give lighting

Figure 6-18.—Streetlight layout.

intensity from .01 to 0.5 footcandle; however, thisvalue is too low for any night activity requiring goodvisibility. Figure 6-21 gives recommendedillumination intensities for specific night activities.The following suggestions should be followed toimprove the efficiency of floodlighting systems:

Select floodlight locations so beams strike the

The minimum point footcandies are

fc min = (0.03) (50) (0.70) (0.56) = 0.58

Therefore, the average-to-minimum ratio of uni-formity would be

2 fc = 3.400.58 fc

surface to be illuminated as nearly perpendicular aspossible.

When lighting irregular surfaces, use two ormore floodlights to reduce sharp shadows caused bysurface contour.

A uniformity ratio of 3.40 meets the ANSI/IESrecommended roadway illumination levels (table 6-1)for a major, commercial roadway.

For lighting extended horizontal surfaces, suchas work areas, mount floodlights high enough tominimize glare.

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Figure 6-19.—Isofootcandle curve.

Figure 6-20.—Roadway perspective view.

For lighting extended vertical surfaces, such assmoke stacks or towers, mount floodlights so distancebetween floodlights or groups does not exceed twicethe distance from the floodlight to the illuminatedsurface.

4. Class OI—Same as Class O except with anauxiliary inner reflector to modify the beam

The suffix letter “B” should be added to the aboveclass designations to indicate when an integral ballastis required.

Use a smaller number of large floodlights Example: A heavy-duty floodlight with an integralinstead of a larger number of smaller floodlights. ballast would be designated as a Class HDB floodlight.

SELECTION OF LUMINAIRES

The National Electrical Manufacturer’sAssociation (NEMA) has classified floodlightingluminaries into four classes according to construction:

1. Class HD (Heavy Duty)—Enclosed with anouter housing into which is placed a separate andremovable reflector, or an enclosure in which a separatehousing is placed over the reflector

2. Class GP (General Purpose)—Enclosed with aone-piece housing with the inner surface serving as areflector and the outer surface being exposed to theelements

3. Class O (Open)—One-piece housing withoutcover glass

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Figure 6-21.—Recommended intensities for specific night activities.

The beam spread can be described in degrees or byNEMA types (table 6-2). The beam spread is based onthe angle to either side of the aiming point where thecandlepower drops to 10 percent of its maximumvalue. The lamp and floodlight NEMA type is given inthe upper left-hand corner of each isofootcandlediagram.

a vertical (V) designation. The horizontal value isalways given first.

Example: NEMA TYPEH V

x7 6

MOUNTING HEIGHT AND SPACING

The NEMA type should only be used as areference. It does not describe the shape of the lightpattern the floodlight produces or the peakillumination level (footcandles). Symmetricalfloodlights have the same horizontal and vertical beamspread and are classified with one NEMA number.Asymmetrical beam spreads have a horizontal (H) and

The size of the area to be illuminated has a directeffect on determining the number and spacing of thepoles. The suggested area that can be covered by asingle pole is four times the mounting height. That isknown as the “2X-4X” rule (fig. 6-22).

Areas lighted from interior poles or other centrallocations (fig. 6-22A) can be more economical, but

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Table 6-2.—Luminaire Designations

Min. Beam Efficiency %

Beam Spread NEMA Type Beam Incandescent, High-IntensityDegrees Designation Description Tungsten, Discharge

Halogen

10 up to 18 1 very narrow 38

18 up to 29 2 narrow 30 30

29 up to 46 3 medium narrow 46 34

46 up to 70 4 medium 50 38

70 up to 100 5 medium wide 54 42

100 up to 130 6 wide 56 46

130 and up 7 very wide 60 50

perimeter locations are also desirable to provideneeded visibility at entrances and exits. in the case ofperimeter poles (fig. 6-22B), if comer locations are notused, the distance from any side location to the edge ofthe area should not exceed twice the mounting height.If building-mounted luminaire locations are limited toonly one side of the area to be lighted (fig. 6-22C), thesystem will be effective for a distance of only twomounting heights unless glare is not a determiningfactor.

According to the 2X-4X rule, the spacing isdetermined to be, from the corner to the first pole, twotimes the mounting height(X). The next pole is set fourtimes this mounting height (X), and the CE willcontinue in this manner until reaching the last pole,which also is to be set two times the mounting heightfrom the far corner. This rule can be used to calculatethe minimum number of poles. For long, narrow areas,it is better to choose several short poles than one tallone, especially since pole costs increase substantiallyabove 40 feet. It is wise to consider severalalternatives, however. to determine the system with thelowest cost.

If the pole is located inside the area to be lighted,there should be at least three floodlights or twostreetlights per pole. For one side perimeter mounting,there should be two floodlights or one streetlight perpole.

6-20

FLOODLIGHT AIMING

When a fixture is aimed at the surface at an angleother than perpendicular, the maximum lighting levelwill always occur behind the aiming point, or point ofmaximum candela. That is important to know when thefixtures are placed close to the base of a tall structure.In this case, the highest lighting level will occur at thebase, even though the fixture is aimed at the top.

For vertical aiming, the aiming point should be twothirds to three fourths of the distance across the area ortwice the mounting height, whichever is the lowestvalue. Higher aiming angles will not improveutilization and uniformity. (See fig. 6-23.)

The highest light level (vertical and horizontal) afloodlight can produce at a distance from the poleoccurs when the maximum intensity or candlepower isaimed to form approximately a three, four, fivetriangle. (See fig. 6-24.) That is useful whendetermining pole height for area lighting or setback forbuilding floodlighting.

Floodlights with NEMA 6 or 7 horizontal beamswill effectively light an area 45 degrees to either side ofthe aiming line. In figure 6-25, the perimeter poleneeds at least two floodlights to cover the area in alldirections. Narrower beam floodlights require lessseparation to achieve uniform lighting.

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Figure 6-22.—2X-4X mounting height rule.

Figure 6-23.—Vertical aiming. Figure 6-24.—Maximum candlepower of illumination.

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Figure 6-25.—Horizontal aiming.

Select lighting fixtures with a beam spread greaterthan the area being lighted. When several units arerequired, good lighting overlap occurs when the edgeof the beam of one fixture coincides with the aimingpoint of the adjacent fixture.

By examining the shape (beam spread) of thelighting pattern emitted by the fixture, you can beginthe process of selecting the NEMA type of floodlightbest suited for the application.

Horizontal and vertical lumen distribution is statedon each photometric test. Generally, the moreconcentrated the luminous intensity (candela), thetighter the beam spread; for instance, the NEMA Type2 Power Spot® floodlight has a beam spread of 22-degrees horizontal by 21-degrees vertical; whereas, aNEMA Type 5 has a beam spread of 77-degreeshorizontal by 77-degrees vertical. The isofootcandlediagrams shown in figure 6-26 compare 1,000-wattmetal halide Power Spot® luminaries of NEMA Type2 and Type 5 when each luminaire is aimed out adistance of twice its mounting height.

The initial footcandle level at the aiming point ofdifferent NEMA types varies a great deal; for example,assume that each luminaire is mounted at a 50-footmounting height and aimed 100 feet (2 x MH) directlyin front of its location. If you are using a NEMA Type 2distribution, the approximate initial footcandle level atthat point would be 20; however, if you are using aNEMA Type 5 distribution, the initial footcandle levelwould be approximately 1.5.

By understanding the intensity of the lightingpattern, you can now appreciate the need for a range ofdistribution patterns.

MANUFACTURER’S LITERATURE

The performance specifications of each model,type, and size of luminaire are provided with thefixture or obtained from the manufacturer’s orderingcatalog. A working knowledge of this information willassist you in selecting and installing the correctfloodlight to accomplish the job. Figure 6-27 shows asample of manufacturer’s literature for a 250- to 1,000-watt light fixture.

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Figure 6-26.—Isofootcandle diagrams.

ISOFOOTCANDLE DIAGRAMS

The isofootcandle diagrams show what the lightlevel will be at any given point. The dimensions for thediagram are based on the mounting height (MH) of thefloodlight. The aiming point (p) is also based on themounting height. Figure 6-27 provides a diagram formounting heights of MH x 0.5, MH x 1, and MH x 2.

The grid pattern is also based on the mountingheight. The grid line values left and right give thedistance to either side of the floodlight. The values up

the side show the distance in line with the aimingdirection of the floodlight. The number 3, for instance,represents 3 x 40, or 120, feet from a 40-foot mountingheight.

Each isofootcandle line shows where thefootcandle level is the same. These lines are identifiedby a letter, which is used with the initial footcandle (fc)table. The footcandle values between isofootcandlelines do not change more than 2 to 1. That makes itpossible to approximate the level between lines.

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Figure 6-27.—Floodlight manufacturer’s literature.

6-24

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The initial footcandle table gives the footcandlevalue for each isofootcandle curve at a specificmounting height. The values for each letter are thesame on each set of curves. That makes it possible tocompare diagrams directly and interpolate betweencurves for different aiming distances.

The mounting heights given in the initialfootcandle table are representative of the wattage andbeam pattern associated with the floodlight. Toconvert to other mounting heights, use the followingformula:

OLD NEW

(FROM CHART) (FROM CALCULATION)

(fc)(MH2) (fc)(MH2)

For example, a 5-footcandle level at 50 feet(isofootcandle curve F) would have a value of 4.13 at a55-foot mounting height.

(5)(502) = (fc)(552)fc = 4.13

In figure 6-27 (aiming point MH x 2), thefloodlight is aimed a distance of two mounting heightsaway from a point on the ground directly below thefloodlight. That would be 80 feet for a 40-footmounting height.

UTILIZATION GRAPH

The luminaire utilization data graph (fig. 6-27)gives the percentage of the initial lamp lumens that fallinto the area being lighted. Knowing this, you caneasily determine the average lumens per square foot, orfootcandles.

The number beside each curve identifies theaiming point, so that the utilization curve can beidentified with the associated isofootcandle diagrams.In the example, for instance, the floodlight aimed twomounting heights away from the pole would have autilization of 35 percent if it were lighting an area threemounting heights wide. The same floodlight aimed atone mounting height away from the pole would have autilization of 45 percent for the same area.

MAINTENANCE FACTOR

Lighting efficiency in floodlighting, as instreetlighting, is seriously impaired by blackenedlamps, by lamp life. and by dirt on the reflectingsurfaces of the luminaire. A maintenance factor (MF)must be applied in the lighting calculations to

compensate for the gradual losses of illumination onthe lighted area.

The following maintenance factors have beenwidely used in industry when manufacturer’sinformation is not available:

Enclosed flood lamps, 0.76

Open flood lamps, 0.65

LIGHT INTENSITY CALCULATIONS

There are a number of ways by which to determineluminaire requirements. Since most methods wouldrequire an engineering background, we will onlydiscuss the basic area lighting design considerationsthat you, as a Construction Electrician, can perform inthe field if engineering assistance is not available. Tobetter understand how the calculations are performed,solve this sample problem:

Determine the average, initial light level in a 160-foot x l60-foot material storage yard using two NEMA6 x 5 HLX 1,000-watt floodlights.

Solution:

1. Apply the 2X-4X rule (fig. 6-28) to determinespacing and mounting height. A 40-foot mountingheight provides MH x 2 or an 80-foot aiming distance.

2. The formula used to calculate the average,initial light level (fc) is as follows:

f c = (N)(LL)(CU)AREA

Figure 6-28.—Material yard sample problem.

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Where:

N = number of floodlights

LL = initial lamp lumens

CU = utilization of the floodlights

From the utilization data (fig. 6-27), you can findthat the utilization for the HLX luminaire aimed at twomounting heights across an area 160 feet or fourmounting heights wide is 38 percent. The initiallumens for the 1,000 watt lamp are 140,000 lumens,obtained from the manufacturer’s literature.Substituting in the formula,

fc=(2)(140,000)(0.38)

=4.2 fc(160)(160)

The maintained light level is obtained bymultiplying the initial light level by the maintenancefactor.

fc = (4.2)(0.75) = 3.15 fc

Using the isofootcandle diagram, we obtain pointby point footcandle values: for example, the center ofthe area occurs just inside isofootcandle line E. Fromthe initial footcandle table, the 1,000-watt HLX at 40feet produces 3.1 footcandles at line E and 7.8 at line F.Since the point is approximately one fourth of thedistance between the two isofootcandle lines, the valuewill be about 4.0 footcandles. With the two floodlightscontributing, the value in the center will be 8.0footcandles. Note that the corners of the area will havevery little light. That is why two or more floodlights arerecommended at perimeter locations.

Another design method that will yield sufficientaccuracy is the quick selector design method. Thegeneral layout considerations shown in figure 6-28should be followed. The watts per square foot obtainedfrom the graph in figure 6-29 produce an averagelighting level accurate to within 20 percent of desiredvalue. That is close enough, since the differencebetween the luminaire requirement obtained from thegraph and the number that will actually be needed tosatisfy the physical requirements of the job involveadjustments greater than 20 percent. It is not unusual,for instance, to need two poles instead of one or torequire three luminaries per pole instead of two. Thiscalculation method should not be used for sportslighting or where the poles are set back from the area tobe lighted.

Before determining the number of luminaries, youshould work out the size of the area to be lighted. Also,

you should determine the maintained illuminationlevel. The following rules of thumb provide someguidelines to help in these decisions.

1. From figure 6-21, you find that the minimumaverage footcandles recommended for industrialyard/material handling is 5.

2. Read up the left side of the graph in figure 6-29until you come to 5. Follow this line across until youintersect the dark diagonal line representing Lucalox®.

3. By reading straight down from this intersectionto the value at the bottom of the chart, you find 0.095lamp watts/square foot of the area is required to light theyard to 5 footcandles.

4. Area to be lighted is (160)( 160) = 25,600 squarefeet.

5. Multiply 25,600 by 0.095 = 2,432 lamp watts.

2,432 is more than two 1,000-watt Lucalox®

lamps

2,432 is approximately equal to six 400-wattLucalox® lamps

2,432 is approximately equal to ten 250-wattLucalox® lamps

6. By using the general layout considerations, youwill find that the most economical floodlightinstallation will use the 400-watt Lucalox® lamps,mounted on 40-foot poles, as shown below.

2X + 2X = 4X = 160 feet

X =160 feet

=40 feet MH.4

SECURITY LIGHTING

Requirements for security lighting at activitieswill depend upon the situation and the area to beprotected. Each situation requires careful study toprovide the best visibility that is practical for guardduties, such as identifying personnel and vehicles,preventing illegal entry, detecting intruders, andinvestigating unusual or suspicious circumstances.

The type of security lighting may be either thecontinuous or the standby type. The continuous type,as the name implies, is on all the time during the hoursof darkness. The standby type is activated eithermanually or automatically when suspicious activity isdetected.

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Figure 6-29.—Lamp watts per square foot chart.

SECURITY AREA CLASSIFICATION

The installation of security lighting is set forth inUnited States Navy Physical Security Manual,OPNAVINST 5530.14. It provides specifications onsearchlights and minimum footcandle requirementsunder given situations. The illumination ofboundaries, entrances, structures, and areas must beaccording to the security manual.

LIGHTING CONTROL

Each security lighting system is designed to meet aparticular need of the activity. The design is such that itprovides the security required at maximum economy.

Multiple circuits may be used to advantage here.The circuits are so arranged that the failure of any onelamp will not darken a long section of the area. The

protective lighting system should be independent ofother lighting systems and protected from interruptionin case of fire.

6-27

The switches and controls of the system should belocked and/or guarded at all times. The most effectivemeans is to have them located in a key guard station orcentral station similar to the system used in intrusionalarm central station installations.

ALTERNATE POWER SOURCES

In general, any security area provided withprotective lighting should have an emergency powersource located within that security area. Theemergency power source should be adequate to sustainall security requirements and other essential servicerequired within the security area. Provisions should bemade to ensure the immediate availability of the

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emergency power in the event of power failure.Security force personnel should be capale of operatingthe power unit. If technical knowledge prevents this,plans must provide for responsible personnel torespond immediately in times of emergency. Inaddition, battery-powered lights and essentialcommunications should be available at all times at keylocations within the secure area.

AIRFIELD LIGHTING

As a Construction Electrician second class pettyofficer. you may be responsible for the installation ofexpeditionary airfield lighting and any repairs ormaintenance required to the installation as well as topermanent advanced base launch and landingfacilities.

Since the Seabees existence is based on being usedin contingency operation, you should know theequipment and components of such a contingencylighting system. The “Expedient Airfields Facility,”13610A, as taken from the Advanced Base FunctionalComponent Facility Listings, provides suchinformation. If the world situation should develop to apoint where the Seabees are alerted and tactical airsupport is required, such a kit would accompany you tothe forward area. For contingency operations, the typesof airfields used may be any of the following:

1. Vertical takeoff and landing (VTOL) airfields

3. Expeditionary airfield (EAF)

4. Strategic expeditionary landing field (SELF)

6-28

2. Vertical short takeoff and landing (VSTOL)airfields (600 and 1,800 feet)

The scope of this chapter is not to provide detailson the electrical systems used at each of the above-mentioned airfields but rather to acquaint you with thecomponents of the systems and their functions for bothexpeditionary and permanent airfields.

Normally, the VTOL airfield is an installationmade of aluminum matting and is used as a forwardlanding field by either helicopters or Harrier type ofaircraft; whereas, the VSTOL airfield, also analuminum matted installation, is usually used as aforward operational facility. The EAF is used by high-performance aircraft and is also used as a forward airfacility. The SELF is similar to the EAF, but with alonger runway.

AIRFIELD LIGHTING SYSTEMS

Airfield lighting systems are designed to aid pilotsduring launch, recovery, and taxi operations. Thereasons for these systems date back to the days ofsmudge pots and the burning of brush piles to helpguide pilots into safe landings. Through the years, themethods of lighting airfields have become much moresophisticated. The lighting systems today have thelight properly distributed, have light controls, and alsohave the ability to define certain areas by means ofdifferent colored lenses and filters inside of thelighting fixtures.

The patterns and colors of the light, as well as themarkings, at each airfield are uniform to enable thepilots to interpret what is seen and then to react almostautomatically. To ensure that airfield lighting standardsare met, the Federal Aviation Administration (FAA) hasbeen tasked with developing the standards and with thepolicing authority to ensure compliance within theUnited States. In addition, FAA standards are used inairfields constructed by the military overseas.

The design of airfield lighting systems mustprovide for locating an obstructional warning system,runway and approach markings, and taxiway andparking facility markings.

AIRFIELD LAYOUT

The VTOL forward operating site is a portableairfield of minimum size designed for operationsdependent upon logistic or tactical support byhelicopters and other vertical takeoff or landingaircraft. The field consists of a surface pad 72 feetsquare, as shown in figure 6-30, view A, withoutlighting, communications, or recovery systems.

A VSTOL facility is a portable airfield capable ofproviding support to VSTOL fixed-wing aircraft aswell as helicopters. The field consists of a surfacedrunway 900 feet long and 72 feet wide and turnoff,parking, and maintenance areas. The nature of theaircraft to be serviced precludes the necessity forarresting gear; however, a field lighting system and acommunications system are supplied to providesuitable aircraft recovery capability. A VSTOL facilitycan readily be converted to a VSTOL air base.

A VSTOL air base also is a portable airfieldcapable of providing support for VSTOL fixed-wingaircraft as well as helicopters. The field consists of asurfaced runway 1,800 feet long and 72 feet wide andturnoff, maintenance, and parking areas to

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Figure 6-30.—Field arrangement direct installation.

accommodate up to 12 aircraft. From the VSTOL air communications system are incorporated to providebase assets, plans are provided from which threesuitable aircraft support. A VSTOL air base readilyVSTOL FACILITIES can be constructed. The VSTOL may be converted to an expeditionary airfield (EAF).air base can support at least one squadron of lightVSTOL attack aircraft and a number of helicopters.

The EAF is a portable airfield that provides asurfaced runway 5,200 feet long and 96 feet wide, as

The nature of the aircraft serviced by the VSTOL airbase precludes the necessity for arresting gear;however, a field lighting system, a Fresnel® lens

shown in figure 6-30, view D, and parking andmaintenance areas for up to six squadrons of light-to-medium fighter/attack aircraft, in addition to a

opt ica l landing system (FLOLS), and a complement of reconnaissance aircraft and

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helicopters. The field includes two M-21 aircraftrecovery systems. two FLOLS, and field lighting andcommunications systems. An EAF may readily beconverted to a strategic expeditionary landing field(SELF).

The SELF is a portable airfield that provides asurfaced runway 8,000 feet long and 96 feet wide, asshown in figure 6-30, view E. The SELF is a pre-positioned war reserve (PWR) setup. The airfieldprovides turnoff, maintenance, and parking areas toaccommodate up to six squadrons of light-to-mediumfighter/attack aircraft, a detachment of tanker aircraft,and various transient logistic support aircraft. TheSELF configuration includes two M-21 aircraftrecovery systems as well as two FLOLS and fieldlighting and communications systems.

AIRFIELD LIGHTING VAULT

The beginning of the airfield lighting system is theairfield lighting vault. The primary power feederenters the vault and supplies power to all of the majorcomponents. These components, in turn, control andoperate the airfield lights. The vault houses the high-voltage power cables, the current regulators, the relaycabinets, and the control panels.

The control cables are installed between the vaultand the control tower or other control points. The high-voltage cables are connected to the regulators and runout to the lights. The lighting control panels are used togive local/remote control of the system. The same typeof remote control panel that is in the vault should alsobe installed in the control tower.

The airfield lighting vault should be about 3,000feet from the runway. This distance ensures that nointerference will occur with the operation of theairfield, and still. it is not so far away that voltage dropsmight cause a problem. The lengths of the controlcircuits between the control tower and the vault arelimited by operational characteristics; for example,size of field, obstructions, and so forth. The minimumdistance is 350 feet; that is to prevent the equipment inthe vault from causing radio interference. If the controlcable leads terminate into actuating coils of relays inthe pilot relay cabinet, the maximum distance is 7,350feet.

Safety

The airfield lighting vault should have certainitems of safety equipment affixed to a board. This

board should be an open display and easily accessible.It should be a minimum of 1/2 inch thick and 4 by 4 feetin width and length. The color should be dark greenwith white letters and borders.

On this board, some of the safety items you shouldhave are as follows:

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Operating instructions for the equipment in thevault

Resuscitation instructions

A phone and a list of emergency phone numbers

A first-aid kit

A switch stick with a minimum length of 5 feetand a 300-pound pull ability

A hemp rope, l/2 inch thick, with a minimumlength of 15 feet

Insulated fuse pullers (for secondary cartridgefuses)

A nonmetallic-encased flashlight marked withluminescent tape to aid in its location in the dark

A shorting stick

Rubber gloves

For the safety of personnel, the airfield lightingvault must be grounded. That may be accomplished byusing two 1/2-inch-diameter, 8-foot-long, copper-plated electrodes, driven into the ground about 8 feetapart and connected in a loop with the vault or groundcable part of the ground grid. This typical connection isshown in figure 6-31.

Power Supply

In many cases, the power supply will not be allhigh or low voltage. In fact, in many expeditionaryairfields, the system may be a combination of high andlow voltage. However, if you are assigned to a naval airstation, chances are that you may be required to main-tain high-voltage airfield lighting systems. Basically,the systems are identical, but because of safety require-ments, the high-voltage systems will have a fewvariables. As an example, take the isolation trans-former (IT) in the high-voltage system; it serves to stepthe voltage down, but its primary purpose is to preventan opening in the primary series loop when a lampfailure occurs. In a low-voltage system, thetransformer is usually a 2: 1 or 1: 1 ratio unit that servesto maintain a closed loop-the same function as theone in the high-voltage system. Even though we will

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Figure 6-31.—Vault grounding arrangement.

be talking primarily about high-voltage systems mostof the time, the functions of the components will applyto either system.

In the 2,400/4,160-volt system, the four-wire wyeprimary source is usually from the base electricalsystem by means of either an overhead or anunderground line. Inside the vault, the lines areconnected to a suitable switch, then to a bus systemconsisting of heavy metal bars that are supported oninsulators. This bus system may be mounted on eitherthe wall or the ceiling.

The bus is divided into a high-voltage (2,400-volt)bus and a low-voltage (120/240-volt) bus for service asfollows: the 2,400-volt bus supplies all of the 2,400-volt regulators and one or more distribution type oftransformers. The distribution transformers supply240 volts to the low-voltage bus that is connected to theregulators operating from this lower voltage as well asfor light and power inside the lighting vault.

Where an emergency power supply is available forairfield lighting, a changeover switch makes theprimary connection to the bus. This changeover switchin its normal position connects the bus to the basepower source. Changing the switch to the emergencyoperation position connects the bus to the emergency

power and, at the same time, disconnects the basepower source.

Emergency power can be supplied by a completelyautomatic engine-driven generator; for example,failure of the base power causes the engine to start. In amatter of seconds, the changeover switchautomatically shifts to the emergency position,connecting the generator to the airfield lighting bus.

At many advance bases, this automatic featuremay not exist. You would have to hook up the propersized generator manually. The generator should have akilowatt (kW) rating capable of handling the airfieldlighting systems, runway edge lights, threshold lights,approach lights, distance markers, optical launchingsystem (OLS), and other circuits that may be used. Thegenerator is three phase; its voltage output varies from120/240 volts delta or 120/208 volts wye to2,400/4,160 volts, and it has to be capable of beingoperated at frequencies of 50 or 60 hertz (Hz).

Constant-Current Regulator

Runway lighting systems are supplied from seriescircuits served by constant-current regulators (CCRs).Each lighting circuit on the airfield has a separateregulator. The CCRs maintain the output currentthroughout its rated output value, depending on theload. Some of the regulators are equipped withbrightness controls. These brightness controls adjustthe brightness of the lamps in the lighting system tocompensate for visibility conditions.

The CCR uses solid-state devices to maintain aconstant-current level in its respective lighting system.The regulators are silicon-controlled rectifiers (SCRs)in a feedback circuit to obtain a constant-current outputinstead of resonant circuits, moving transformerelements, or saturable reactors. The SCRs arecontrolled to vary the part of a cycle during which thecurrent is permitted to flow into the load circuit. In theload circuit, the current is maintained constant at anyvalue preset with the brightness control by means of afeedback circuit as the load resistance is varied frommaximum to zero. The block diagram (fig. 6-32) showsthe elements constituting the regulator. Load current ismeasured by the current transformer and the Hall unit,or multiplier unit, that has an output voltageproportional to the square of the load current. The Hallunit, or multiplier, output is filtered and fed into theinput of an amplifier and compared with an input froma brightness control potentiometer. The output voltageis a function of the difference between the two inputs.

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Figure 6-32.—Block diagram of constant-current regulator.

The output voltage is applied to the input of the gatepulse generator that determines the condition angle ofthe SCRs and changes it to bring the system toequilibrium. Transient overload protection is providedfor the semiconductor element of the Hall unit. Open-circuit protection is provided when no current is drawnby the load and the brightness potentiometer outputvoltage is any value other than zero. Under these con-ditions, the SCRs will be prevented from conducting,and the output voltage to the load will be zero.

Remote Control

The airfield lighting systems may be operatedcompletely by the remote control panel assembly. Theonly operation required at the electrical distributionvault is to ensure that all circuit breakers are engaged,

the regulators are set for remote operation, and the loadswitches are in the ON position. The electrician mustensure that the unit is installed properly and that thedifferent levels of light intensity desired can beachieved. Figure 6-33 is a typical view of a remotecontrol unit that you may encounter in the installationof a contingency airfield lighting system.

The unit uses 120 volts as the control voltage withlow-burden pilot relays to compensate for the voltagedrop caused by the long distances usually foundbetween the control tower and the vault. In this type ofcontrol system, the switches on the control panelactuate low-burden relays; these, in turn, actuate thepower switches, contactors, and the relays controllingthe regulators that supply the airfield lighting circuits.

Figure 6-33.—Typical remote control panel operating controls.

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Both the tower and vault control panels are wiredinto a double-throw “transfer-relay cabinet” located inthe vault. That is shown in figure 6-34 with a single linerepresenting the control cable. The transfer relay canconnect either control panel to the pilot-relay cabinet.It can switch the system control from the tower to thevault or from the vault to the tower. The transfer relayhas an eight-pole, double-throw, transfer-relayassembly unit. This unit is actuated by a toggleswitch.

The low-burden pilot relay is designed to operateat a wide range of voltages lower than the designedl20-volt ac rating. The pilot relay can be actuated atvoltages from 50 to 90 volts ac.

The standard control cable is a No. 7 conductor,600-volt, insulated, polychloroprene-sheathed cable.One conductor (black) is a No. 12 American WireGauge (AWG), and the remaining conductors are No.16 AWG. The No. 12 conductor is the hot lead, and theNo. 16, the “switch legs.”

LIGHTING CIRCUITS

Several different lighting circuits are used on air-fields: runway edge lighting circuits, taxiway lightingcircuits, approach lighting circuits, obstruction ligh-ting circuits, beacon lighting circuits, and the

Figure 6-34.—Airfield lighting control system

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and the condenser discharge circuits. Each of thesecircuits will be covered separately.

Runway Edge Lights

Runway edge lighting is designed to show thewidth and length of the usable landing area; there aretwo rows of lights—one row on each side—that run thelength of the runway. The light they give off is aviationwhite (clear). The edge lights are installed not morethan 10 feet from the edge of the full-strength runwaypaving. Both lines of lights will be the same distancefrom the runway center line. It is best if the lines oflights are located as close to the runway as the basemounting for the lights allows. The lights are equallyspaced along the runway at distances not to exceed 200feet. (See fig. 6-35.)

The runway lighting controls are set up so that thelights on intersecting runways cannot be on at the sametime. Also. the controls must turn all the light systemsof one runway on at the same time. The runway edgelights are controlled so all the lights are the samebrightness. In a high-intensity system, threshold lightsare one step higher than the runway edge lights exceptwhen the runway edge lights are at full brightness. Atthis time. both the runway edge lights and the thresholdlights are at full brightness. In a medium-intensityrunway lighting system, all lights (runway edge lightsand threshold lights) are the same brightness.

In some instances, it is a good practice to userunway edge light fixtures and lamps for the thresholdlights, so that the difference is noticeable when thethreshold lighting configuration has to be stepped upone brightness higher than the runway edge lights. Todetermine the number of circuits required for runwayedge lights, you need to determine the length of therunway. You determine the number of lights on onecircuit by considering not only the number of lightsconnected to the circuit but also the voltage loss for thecircuit cables and the feeder cables from the vault to therunway. If this distance is long, you may need to adjustthe number of lights in the circuit.

Do not load the regulator less than one half of itsrated kilowatt (kW) output. If more than one regulatoris required, each regulator should be equally loaded.

Each light circuit will be fed by a series loop. Thecurrent leaves one terminal of the CCR, goes throughthe circuit to each light unit, and returns to the otherterminal of the regulator.

Taxiway Lights

Taxiway lights are used to show the pilot the widthand direction of the “taxiing route.” The lights areaviation blue in color. They are basically the same asrunway lighting circuits.

Approach Lights

Runway approach light systems are used on high-intensity-equipped runways. The system starts at thethreshold and extends outward for 3,000 feet. Whenthe full length of the land cannot be used, the greatestlength possible is used. Condenser discharge (strobe)lights that put out a high-intensity, bluish white lightstart at the 3,000-foot mark and flash in sequencetoward the threshold. The system is used to help thepilots land under low-visibility conditions. Thecondenser discharge lights are discussed in more detaillater in this chapter.

The lights of the approach system are located on animaginary line that extends from the runway centerline. Each light bar is centered on this imaginary lineand spaced the same distance apart for the entire 3,000feet.

The supply and control circuits of the approachlighting systems are installed underground and areusually in conduit; however, in some cases, the last2,000 feet of the approach lights can be above ground.In some cases, the supply cable from the series circuitcan be direct burial.

Aboveground circuits may be used for approachlighting when the cables do not present a hazard tovehicular traffic or are not accessible to unauthorizedpersonnel and animals. The cable must be installed,normally, a minimum of 22 feet above ground. Wherethe area is completely closed off (fenced): a lowerground clearance is acceptable. Control circuits mayuse a small-size conductor when it is supported by amessenger cable. DO NOT USE ALUMINUMCONDUCTORS. Use standard overhead constructionpractices for series circuits. Use lightning arresterswhen the cables go from underground to overhead.Connect the ends of the circuits in the same way asunderground cables.

Besides the basic runway light configuration, thereare other airfield lighting aids to help the pilot inlanding and takeoff operations. Four such aids forlanding and taking off are the visual approach slopeindicators (VASI), the Fresnel® lens optical loadingsystem (FLOLS), the runway distance markers, andthe threshold lights.

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Figure 6-35.—Typical airfield lighting layout.

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VISUAL APPROACH SLOPE INDICATORS(VASI) —The VASI system provides the pilot withvisual approach slope angle information while on finalapproach. The VASI system is helpful during daylightor night operations. There are three standard VASIsystem configurations: VASI-4. VASI-12, and VASI-16. We will discuss the VASI-12 system as it willappear on most Navy airfields.

The VASI system consists of twelve light boxeswith three lights in each box. There is one completesystem for each end of the runway. There are two pairsof bars-one pair of bars on each side of the runway.Each wing bar is composed of three light boxes (fig.6-36). The set of bars nearest the threshold is called thedownwind bars. and the other pair. the upwind bars.Each light box projects a beam of light that is white(clear) in its upper part and red in its lower part. Thelights are arranged so that the pilot of an airplane,during the approach. sees all of the wing bar lights asred when below the glide slope. When on the glideslope. the pilot sees the downwind bar lights as whiteand the upwind bar as red. When above the glide slope,the pilot sees all the wing bar lights as white.

FRESNEL® LENS OPTICAL LANDINGSYSTEM (FLOLS).—Another system designed forcontinuous automatic operation is the FLOLS. (See

fig. 6-37.) It also provides optical landing assistanceby indicating the correct glide slope angle to the pilot ofan approaching aircraft. This system contains twogroups of horizontal datum lights set perpendicular tothe approach path; two vertical bars of wave-off lights;two double types of cut lights; and a source lightindicator assembly, consisting of five vertical cellassemblies. Each cell assembly contains source lights,a Fresnel® lens. and a lenticular lens. The arrangementof these lenses gives the pilot the glide slope. The unitshould be set up on the left side of the runway, from thepilot’s perspective, about 10 feet from the edge of thepavement and 750 feet from the runway threshold.

Power for the system is provided by an installedfield lighting supply or by an auxiliary, power unitcapable of 20 kilowatt (kW). 60 hertz (Hz), three-phase, 120 volts phase to neutral.

RUNWAY DISTANCE MARKER. —With theuse of high-speed aircraft, the runway distance markersystem is needed to tell the pilots how much runway isleft to take off or to land. The distance information, inthousands of feet, is given by numbers on the side of themarker. The numbers are on two sides of the signs, sothat the distance left can be shown for both directions.There is one row of signs on each side of the runway.Each row is the same distance from the runway center

Figure 6-36.—Visual approach slope indicators (VASI).

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Figure 6-37.—Fresnel® lens optical landing system (FLOLS).

line. They are spaced 1,000 feet apart. The signs havepainted numbers that are lit so they can be seen at nightand during periods of restricted visibility.

The power supply for serving the runway distancemarkers should be from a separate series circuit. Do not

THRESHOLD LIGHTS. —The threshold lightsare a part of the approach light system. Four sets oflight systems are used in the threshold lightconfiguration. These lights are as follows: inboardthreshold lights, winged-out threshold lights,prethreshold wing bars, and a terminating bar. These

have the markers supplied from circuits feeding either four sets of lights are installed on both ends of thethe runway, threshold, or the approach lighting runway and are used to mark the beginning of thecircuits, since these circuits are operated at variousrunway.brightness steps, and the signs are operated at their fullbrightness at all times. Also, do not connect them to

Inboard Threshold Lights.—Inboard threshold

taxiway circuits because of the intermittent operationlights are installed in the area at the end of the runwaybetween the two runway edge light lines. This line of

requirements. The cable used for the runway distancemarker circuit is a single conductor, No. 8 AWG,stranded, 5,000 volts.

lights will be at a right angle to the runway center line.They arc as close to the full-strength paving aspossible but not more than 10 feet from it. The lights

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are spaced 10 feet apart. Their color is aviation green.(See fig. 6-35.)

Winged-Out Threshold Lights.—The winged-out threshold light bar is on the same light line as theinboard lights. These lights extend out from the end ofeach side of the inboard light bar. Each bar is 40 feetlong and has nine lights spaced 5 feet apart. The firstlight location is at the intersection of the runway edgelight line and the threshold light line. The color of theselights is also aviation green. (See fig. 6-35.)

Prethreshold Wing Bars.—A prethreshold wingbar is located on each side of the extended runwaycenter line 100 feet out from the threshold. Theinnermost light of the bar is 75 feet from the center line.Each bar (14 feet long) has five aviation red lightsspaced 3 l/2 feet apart. (See fig. 6-35.)

Terminating Bar.—The terminating bar islocated in the overrun area. The light bar is at a rightangle to the runway center line and 200 feet out fromthe runway threshold (100 feet out from theprethreshold lights). There are 11 aviation red lights inthe bar. The bar is 50 feet long and is arranged so thatone half of the bar is on each side of the center line. Thelights are arranged in three groups: five lights spaced3 l/2 feet apart on a 14-foot bar in the middle and, oneach side, one I O-foot bar of three lights spaced 5 feetapart. (See fig. 6-35.)

Obstruction Lights

Obstruction lighting is a system of red lights usedto show the height and width of natural or man-madeobjects that are hazardous to air flight. These lights arefor the safety of aircraft in flight. The lights must beseen from all directions and are aviation red in color.

The obstruction lights are turned on during allhours of darkness and during periods of restrictedvisibility. They are placed on all objects with an overallheight of more than 150 feet above ground or waterwithin the airspace.

At least two lights (or one light fixture with twolamps) are located at the top of the obstruction. Whenthe top of an obstruction is more than 150 feet abovethe level of the surrounding ground, an intermediatelight. or lights, is provided for each 150 feet. Theselights are equally spaced from the top to the bottom.

Where obstructions cover an extensive horizontalplane, the top lights will be put on the point or edge ofthe obstruction highest in relation to the obstruction-marking surface. The lights should not be spaced more

than 150 feet apart. This spacing indicates the generalextent of the obstruction. Double lights are used at thehorizontal limits of the obstruction, and single lightsare used for intermediate lights. If two or more edgesare of the same height. the edge nearest the airfield islit.

On overhead wires, obstruction lights are placed atintervals not exceeding 150 feet and at a level notbelow that of the highest wire at each light location.

Obstruction lighting systems are served by, either aseries or a multiple circuit. The type of circuit useddepends on the location of the obstruction and the typeof lighting equipment installed. The six most commontypes of circuits that may be used for the obstructionlights are as follows:

1.

2.

3.

4.

5.

6.

Low-voltage multiple service from the vaultwhen the length of the circuit is less than 800feet

Series circuit when the load is less than 4kilowatts (kW) from a taxiway type of regulatorin the vault

Twenty-four hundred-volt service from thevault to a distribution transformer to serve amultiple circuit

Twenty-four hundred-volt service from thevault to a CCR that serves a series circuit

Control circuit from the vault that operates anyof the previously listed circuits by means of arelay

Time clock or a photocell with a series ormultiple circuit for the lights

Obstruction lights on objects that are more than150 feet above ground or water must be on all the timeor controlled by a photocell.

Beacon Lights

The landing facility location is provided by theaeronautical beacon. The beacon is a high candlepowerflashing light visible throughout 360 degrees. Itprovides the pilot a visual signal to locate and identifyairfields during night operations or during periods ofrestricted visibility, day or night.

There are three functional types of beacons that wewill discuss: the airport beacon; the identification, orcode beacon; and the hazard, or obstruction beacon.

The airport beacon is normally located within5,000 feet of the airfield. The rotatable unit will display

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alternate double-peaked white flashes and a singlegreen flash to identify the airfield as a military facility.The size of the unit is about 24 inches; a rigid drumduplex type with a clear double-flasher spread-lightlens on one end and a plain green lens on the other.There is an automatic built-in lamp change in case oflamp burnout. An illustration of a typical airportbeacon is shown in figure 6-38. Beacon lights may bemanually controlled from the tower or from thelighting vault. If the facility is not operated on a 24-hour basis, an automatic control is possible with aphotoelectric control that turns the unit ON or OFFautomatically.

The identification beacon, or code beacon,identifies an airfield where the airport beacon is morethan 5,000 feet away from the airfield or where two ormore airfields are close enough to use the same airportbeacon. This nonrotatable unit can be seen from alldirections and is equipped with a flasher switchoperating at 40 flashes per minute with a rangeadjustment. The beacon has white lenses with greenfilters and is manually controlled from the tower butmay be controlled automatically.

The third beacon, the hazard, or obstructionbeacon, furnishes visual identification of naturalfeatures or structures that are 150 feet above airfieldelevation for on-station or off-station hazards; that is,

tanks, towers, stacks, and so forth. The beacon useswhite lenses with red filters and is manually controlledfrom the tower. When automatic controls are desirable,a photoelectric control system may be used. Since thebeacon does not rotate, a flashing system isused-flashing 26 times per minute. The beacon lampsand motor require 120 volts for operation. Most of thetime, this unit is fed by a 120/240-volt or 120/208-volt,three-wire service. You can use a 120-volt, two-wireservice, but it is not recommended. When the lightingvault is less than 800 feet away from the beacon, a low-voltage service can be used. When the vault is morethan 800 feet away, high voltage (2,400 volts) from thelighting vault is used to supply a distributiontransformer at the base ofthe beacon. You also can runa control wire from the vault to the beacon to operate arelay that, in turn, switches on the power from a localsource near the beacon. The last method works bestwhen the beacon is at a remote location from theairfield.

Because of the extreme hazard to life, an alternatelow-voltage source near the beacon is usually required.

TYPES OF FIXTURES AND LAMPS

To meet different system requirements, you musthave different intensities of lighting. Along with thesesystems, you need different kinds of fixtures to meet

Figure 6-38.—Beacon with one door open and base pan dropped.

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the needs of designated locations. In each fixture, acertain type of lamp must be used to give off the rightkind of light. A runway light fixture, in a series loopsystem, requires an isolation transformer (IT). Thesetransformers must be matched to each lamp accordingto amperage and watts. Figure 6-39 provides you witha pictorial view of the lighting fixtures used incontingency airfield operation; table 6-3 provides theNaval Air System Command part number of eachfixture plus the number of fixtures required per giventype of field installation.

Several different types of lights are used. Theexact type used depends on the system. Not only arethere different fixtures for different widths of runways,but there are different intensities. In most cases, high-intensity lighting systems are used for high-speed air-

craft. Also, high-intensity lighting systems are requiredduring low-visibility conditions.

CONDENSER DISCHARGELIGHTING SYSTEM

The condenser discharge lights are added to makethe approach system complete. Because the lampsflash on and off to give a stroboscopic effect, the termstrobe is used for these lights. From here on out, theterm strobe will be used when referring to condenserdischarge lights.

The transformer and the master sequence timercabinet are located in a small vault or pad near thecenter ofthe approach system. The vault or pad shouldbe secured so neither animals nor unauthorized per-sonnel can enter..

Table 6-3.—Airfield Lighting Equipment Required.

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1. Electrical distribution vault

2. Remote control assembly

9. Approach light 17. Status light

10. Strobe light 18. 500-W floodlight

3. 4-kW constant current regulator 11. Extended line-up light 19. 200-W floodlight

4. 15-kW constant current regulator 12. Strobe timer 20. Wind cone assembly

5. Center-line sight 13. Strobe power supply 21. Rotation light

6. Runway light 14. Obstruction light 22. Transformer - runway and approach

7. Threshold light 15. Circling guidance light 23. Transformer - taxiway

8. Taxiway light 16. Rotating beacon light 24. Transformer - work area

Figure 6-39.—Airfield lighting components.

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The major components of the condenser dischargelighting system are the elevated and semiflush strobelight units, the master sequence timer cabinet(containing the local/remote control unit, the monitorand control chassis, and the master sequence timer),and the tower control unit.

Strobe Light System

The strobe lights are installed on each center-linelight bar starting 300 feet from the runway thresholdand extending outward for the length of the system.The strobe light will be located on the center-line lightbar, midway between the center light and the next lighton either the left or right side. They can be placed infront of the light bar but not more than 10 feet. Nomatter where they are placed, they must be in the sameposition on each light bar throughout the entireapproach system.

In the overrun area, the strobe lights are installed asflush lights. Starting with the 1,000-foot bar (decisionbar) and going out, an elevated type of strobe light isused. An elevated approach light bar looks like the oneshown in figure 6-40.

The strobe lights are controlled from the remotecontrol panel. They can be turned on and offindependently or so triggered that they come on whenthe approach light switch is in either the third, fourth,or fifth brightness position. The brightness of thestrobe lights cannot be controlled.

The strobe lights put out a high beam of light thatpeaks at 30 million candlepower. DO NOT LOOKINTO THE BEAM OF LIGHT WHEN YOU ARENEAR ONE OF THE LAMPS OR YOUR EYESCOULD BE DAMAGED. The system we discuss hereis one of several different types manufactured. Theoperation is the same no matter who manufacturesthem. Your knowledge of one will give you anunderstanding of the others.

Strobe lights are either flush mounted or elevated.The operation of the flush light is exactly the same asthat of the elevated light unit. The main differencebetween the units is the way in which the componentsare arranged. We will be discussing the condenserdischarge strobe light unit (figure 6-41); the numberedareas in parenthesis will refer to the numbered items inthe figure.

Figure 6-40.—Elevated approach light bar.

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Each strobe light has four inputs from the rest ofthe system: (1) 240 volts ac, (2) ground, (3) 120 voltsac timing pulses at the rate of two per second, and (4) adc voltage connection to the monitor system. Theseinputs are plugged into a cable through a four-pinconnector (No. 10). The unit steps up the 240-volt acinput voltage to 1,460 volts ac with a transformer (No.15) and passes this voltage through a full-waverectifier circuit of vacuum tubes (No. 13). Theresultant 2,000 volts dc is applied to the electrodes of aflashtube and across the flash capacitor (No. 4).

The xenon-filled flashtube will fire only whenionization is initiated by a trigger pulse of about 5,000volts applied to its third electrode. This pulse issupplied by a trigger coil. At the same time that theflash capacitor is storing its charge, the triggercapacitor is also being charged by the primary of thetrigger coil, which is an autotransformer, and cuts thebleeder resistors in series out of the circuit. When thel20-volt ac timing signal arrives, it is applied to thecoil of the trigger relay (No. 9), thus closing the relaycontacts, allowing the trigger capacitor to dischargethrough the primary ofthe trigger coil. That generatesthe necessary trigger pulse in the secondary of thetrigger coil, the flashtube fires, and the flash capacitordischarges across the flashtube electrodes. The flashcapacitor discharges down to the deionizationpotential of the flashtube, at which point the tubebecomes a nonconductor. The light-producing arcceases, and the charge cycle begins again.

The charge stored in the flash capacitor is apotential safety hazard. To make sure that thecapacitor is discharged when the light unit is shutoff, provide a discharge circuit by a series of bleederrelays. The bleeder relay (No. 5) closes this dischargecircuit when the power to the transformer is turned off.

The current that charges the flash capacitor createsa pulse voltage in a surge resistor twice each second. Apart of this voltage is applied to a silicon rectifierthrough a tap-off of the surge resistor. The rectifiedvoltage is then filtered and applied to the monitor relay.The value of this voltage is sufficient to keep themonitor relay energized when the unit is flashingnormally. When the unit stops operating because of acomponent failure in the unit, the absence of the pulsevoltage at the surge resistor will allow the contacts ofthe monitor relay to close. This action completes acircuit from the monitor connection through a monitorresistor of 22 kilohms to ground. The monitor andcontrol chassis react to the ground by warning theoperator.

Master Sequence Timer Cabinet

The master sequence timer cabinet has all of thecontrols for the strobe light system except the towercontrol unit. The cabinet is supplied from a 240-volt,phase-to-ground circuit. Our discussion of how thesystem operates is keyed to the numbered items infigure 6-42.

LOCAL/REMOTE CONTROL UNIT. —Thelocal/remote control unit (No. 1) gives you a way toturn the system on locally or give control to the tower.In the center of this unit is a control knob with threepositions: REMOTE/OFF/LOCAL-ON. There aretwo red indicator lights above the control knob and twogreen lights below it. When the control knob is in theLOCAL-ON position, the system is turned on, and redlights will glow to indicate that the system is onLOCAL CONTROL. The green monitor lights shouldburn unless there is a fault in the system; in which case,they will go out. When the control knob is placed in theREMOTE position, the system can be turned on and offat the tower control unit. The red indicator lights willgo out, but the monitor lights will continue to work asbefore. You should remember that the tower has nocontrol except when the switch is in REMOTE.

MONITOR AND CONTROL CHASSIS. —Themonitor and control chassis has several functions.They are as follows:

1. It de-energizes the monitor lights in both controlunits when a set number of lights stop working.

2. It has a step-down transformer to supply thevoltages needed for control and indication.

3. It has a diode rectifier that supplies direct cur-rent for relay operation.

4. It has the fuses that protect the master sequencetimer, the indicator circuits, and other components.

The main power transformer in the monitor andcontrol chassis is energized all the time from a local240-volt ac supply. The secondary voltage from thistransformer energizes the indicator lamp transformerand the transformer of the dc circuit. The indicatorlamp transformer supplies 12 volts ac to the indicatorlights in the local/remote control unit. The transformerfor the dc power will supply 95 volts ac to a bridgerectifier that supplies 120 volts dc to the dc monitorcircuit.

As long as the master control switch is on, power isfed to the tower csontrol unit no matter what positionthe local/remote control unit switch is in. When the

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1. Cabinet light (240 V)

2. Light switch and fuse

3. Safety interlock switches

4. Flash capacitor

5. Capacitor bleeder relay

6. Fuse and switch, 240-volt power

7. Connector receptacle

8. Monitor relay

9. Trigger relay

10. Four-pin connector

11. Tracks

12. Flashtube socket

13. Rectifier tubes

14. Plate caps

15. Transformer

16. Reflector

17. Glass

18. Door stop and bracket

19. Lightning arresters

Figure 6-41.—Condenser discharge strobe light unit.

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1. Local/remote control

2. Elapsed time meter

3. Main relay and switch

4. Sensitivity rheostat

5. Sensitivity selector switch

6. DC power supply

7. DC regulator tube

8. Fuses

9. 12-volt transformer

10. Terminal blocks

11. Lightning

12. Timer motor

13. Timer switches

14. Cabinet light (240 volts)

15. Fuse and light switch

Figure 6-42.—Master sequence timer and controls.

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flasher control switch in the vault control unit isclosed, the dc power interlock relay closes andenergizes the monitor lights in the tower control unit.The unit responds in the same way as if the systemwere in full operation and working well. For thisreason. the tower personnel must be notified when theswitch in the local/remote control unit is in the OFFposition. When the flasher control switch on thelocal/remote control unit is in the OFF or LOCAL-ONposition, the red indicator lights tell you that the towercontrol unit is not in full operation.

There is a monitor-sensing relay to monitor theoperation of the strobe lights. When all the light unitsare working correctly, there will not be enough currentthrough the coil ofthe monitor-sensing relay to actuatethe relay. A variable adjustable resistor can be adjustedso that there will be 7,333 ohms of resistance betweenthe monitor-sensing relay and ground. A resistance of7,333 ohms equals three 22-kilohm resistors in series.The monitoring circuit in each light unit has a 22-kilohm resistor. So, if you take the three 22-kilohmresistors out of the monitor control unit, the monitor-sensing relay actuates when at least three light unitshave ceased to work and their monitoring circuits aregrounded, as described earlier.

The sensitivity selector switch lets you reduce thenumber of malfunctioning lights needed to actuate themonitor-sensing relay by increasing the currentflowing through its coil. There are three 22-kilohmresistors in the monitor control unit. Each of these threeresistors simulates the effect of a grounded monitorconnection to one of the lights.

If the monitor-sensing relay is tripped, the monitorlights on the local/remote control unit will go out. Atthe same time. the monitor lights in the tower controlunit go out and a buzzer sounds.

The adjustment for the sensitivity of the monitorsystem is made at the monitor and control chassis in themaster sequence timer cabinet.

With all of the strobe lights operating and thesensitivity selector switch in the No. 1 UNIT position,the green monitor lamps should be on. If you turn thestrobe light units on and the monitor lights do not comeon, you need to adjust the sensitivity of the variableresistor (sensitivity rheostat). You need a smallscrewdriver to fit the slot in the rheostat shaft (No. 4).Turn the shaft clockwise as far as it will go (about half aturn). The green lamps should now be lit. Now, turn therheostat counterclockwise slowly until the greenlamps go out. Then turn the rheostat back clockwise

slowly and stop as soon as the green lamps light. Checkthis setting by slipping a piece of paper between thecontacts of one of the timer switches. The monitorlamps should go out. Remove the paper and turn thecontrol switch to OFF for a few seconds and then toON. The green lamps should now stay lit. Repeat thisprocedure for different lamps and shift the rheostatslightly if you need to until you find a setting that willoperate for any of the approach lights.

Change the sensitivity selector switch to the No. 2UNIT position and repeat the procedure whileblocking two ofthe switches with pieces of paper. Thatis like having two strobe light units out and should havethe same results as before. Restore the monitor lightsthe same as before. Repeat the procedure with thesensitivity switch in the No. 3 UNIT position while youblock three of the timer switches. Now, check theoperation ofthe monitor circuit with number 1, 2, and 3strobe lights out.

When you find the correct setting of the rheostat,no further adjustments should be needed. When yourbase requires the selector switch to be on the No. 1UNIT position, then, in proper operation, if one strobelight fails, the alarm is silenced by just moving theselector switch to the No. 2 UNIT position. The switchis left in this position until the bad strobe light is fixed.At that time, the selector is returned to the No. 1 UNITposition.

MASTER SEQUENCE TIMER. —The mastersequence timer controls the order and rate of thetriggering impulses to the light units. The timer has twocamshafts driven by a motor (No. 12) through areduction gear. The cams actuate 30 contacts (No.13)—one for each light unit—staggered on the shaftsso that the contacts are closed in rapid succession as theshafts turn. Note that although there are 30 contacts,only 28 are used. Each ofthe 28 contacts is electricallyconnected to one of the light units. Thus, when themotor is energized, the contacts are momentarilyclosed in a predetermined sequence twice each second.That provides a series of 120-volt ac pulses to thetrigger relays in the lights. These pulses are known asthe timing circuit. Power for the 120-volt motor and the120-volt timing pulses comes from the monitor andcontrol chassis. An elapsed time meter (No. 2) ismounted next to the timer to show the total time theequipment has been in use; thus it serves as a guide formaintenance. Forty-five lightning arresters (No. 11)are installed in the lower part of the cabinet to protectthe equipment from voltage surges on any ofthe lines.

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Tower Control Unit

The control switch on the tower control unit worksonly when the local/remote control unit in the timercabinet is in the REMOTE position. The audible andvisible monitoring alarms, however, are operablewhenever the system is in use, even if the local/remoteunit is at the LOCAL-ON position. Adjustments areprovided on the panel for regulating the brightness ofthe two green monitor lights and the loudness of thebuzzer. A push-button switch is used to test theoperation of the buzzer.

MAINTENANCE OF AIRFIELDLIGHTING SYSTEMS

Regardless of the design of an airfield system,maintenance is highly recommended to ensure theoperational dependency of the field. Routinescheduled downtime is much better than unscheduleddowntime in the midst of an operation. Simple visualinspection plus periodic resistance readings of circuitdevices, components, and cables reveal probabletrouble areas.

Do not get caught in the “jury-rigged trap.” Thistendency to patch, bypass, piece together, or otherwiserig a system to work “just for a little while” can be asdangerous as a coiled rattlesnake. That “temporaryfix” is just sitting there waiting to catch someuninformed individual sent out to work on the system.This section covers routine maintenance for airfieldlighting and underground systems, troubleshootingcable systems, and cable splicing and repair.

ROUTINE MAINTENANCE

Routine maintenance includes, but is not limitedto, cleaning, adjusting,lubricating, painting, andtreating for corrosion. Components and connectionsmust be checked for condition and security. Theinsulation of the conductors should be checked forgood condition and burns, scrapes, breaks, cracks, orevidence of overheating.

Visual Inspection

During your visual inspection of an airfieldlighting wiring system, you should check the constant-current regulator (CCR) for chipped or crackedporcelain bushings, correct connections, proper fusesand switches, and relays for freedom of movement.Only relay panel covers should be removed. It is not

necessary to open the main regulator tank. All coversthat are removed should be cleaned and thenreinstalled tightly. Cable and isolation transformerconnectors require close visual inspections for cuts,bruises, or other mishandling; these conditions couldcause premature failure to the system. The matingsurfaces of these molded rubber connectors must beclean and dry when they are plugged together. Eitherdirt or moisture prevents the mating surfaces frommaking complete surface contact and causes a failureat the connector. When connectors are pluggedtogether, trapped air can cause them to disengagepartially. Wait a few seconds and push them togetheragain. Apply two or three turns of tape to hold them inplace. When the connectors are clean, dry, and tapedproperly, the connection is equal or superior to a high-voltage splice.

Check light fixture connections for tightness.Look for cable bends that are too sharp; sharp bendscan cause insulation breakdown or connector failure.

Operational Check

Once all components of the system have beenvisually inspected for damage and the cable system hasbeen checked with a megger and hi-pot, make anoperational check ofthe entire airfield lighting system.

1. Working from the control tower with anobserver in the vault, operate each switch of the airportand taxiway panel, so that each position is reached atleast twice. You must have radio or telephonecommunication with the observer in the vault duringthis operation. The observer in the vault determines thateach switch properly controls its corresponding circuit.

2. Repeat this operation from the vault (alternatecontrol panel) in the same manner, assuring that eachswitch position is reached twice.

3. Now, repeat the test by using the local controlswitches on the regulator.

4. Operate each lighting circuit at maximumbrightness for 6 continuous hours. Make a visualinspection of all lights, both at the beginning and at theend of this test to assure that the proper number of lightsare operating at full brightness. Measure lamp terminalvoltage on at least one lamp in each multiple circuit toassure that this voltage is within ±5 of the rated lampvoltage. Dimming of some or all of the lights in a circuitindicates grounded cables.

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Condenser Discharge Light System

Periodic maintenance of this system is fairlysimple. Remember, however, that high voltages existin the components of the system and you must be extracareful. One such area is the flash capacitor. Thiscapacitor may contain as much as 2,000 volts. Anyoneworking on the light fixture should make sure thatthis capacitor is discharged before working on thelight unit. The capacitor should bleed down throughits resistor network in 5 seconds; however. thecapacitor should be shorted out before any work isdone inside the unit. In a flush unit short betweenterminals 7 and 10 ofthe terminal board with a shortingstick. In the elevated light, short the two contacts on theleft side of the flashtube socket. That must be donebefore any work is done inside the light unit, such aschanging a flashtube or cleaning the reflector.

WARNING

Anyone working on a condenser dischargelight system must make sure that the capacitoris discharged before working on the light unit.

Since these are sealed units, cleaning the reflectorsrarely should be required. When such cleaning isrequired, be sure to use a nonabrasive cleaner. Thelenses in both the ‘elevated and flush units should becleaned periodically,depending on the localconditions.

Inspect the timer contacts to see that they are cleanand making good contact. If not, the stationary timercontacts can be adjusted. The timer gears ofthe mastersequence timer require periodic lubrication. Match thegrease to the ambient temperatures expected in yourparticular area. NEVER use a graphite-based grease,as graphite is electrically conductive.Check to seethat both pairs of green indicator lights will light.When only one lamp is lit on either unit, the other bulbhas burned out. To replace one of these bulbs, removethe front panel, pull off the colored lens, push out theold bulb, and insert the new bulb from the front of thepanel. Replace the lens and panel.

Underground Distribution System

Normally speaking, underground systems that areproperly installed require little maintenance of theroutine type. Since both the equipment and the cableare well protected from man and the elements, thesystem normally is not subject to the same problemsthat overhead systems experience.

In some areas, groundwater or dampness maycreate some problems for underground systems byincreasing rust or corrosion. Racks and splice boxesmay require more painting and other rust or corrosionmaintenance. Look especially for rusted nuts on boxesand rack hangers. They should be cleaned and painted.The manholes and vaults should be cleaned. Theseareas should not be used for storage or should trash beallowed to collect in them.

Check the manhole walls for evidence of cracks,breaks, or other evidence of water seepage or leakage.Check empty ducts for plugs and evidence of waterseepage.

You will find manholes with enough water in themto hamper or prohibit work operations. In such cases,bail the water out with a bucket and rope or pump it outwith a manhole pump. Sometimes sump holes are builtinto the floor of manholes, and these provide places tobail from or to pump from the lowest places in themanhole. When water runs into a manhole fromunoccupied ducts, hard rubber plugs are provided tostop or slow the water. When the manhole pump is used,place it in a position so the flow of water will be awayfrom the manhole. That would be on the downhill side.Place the pump at least 10 feet from the manholeopening. The pump has a hose to be inserted in themanhole and an outlet hose to carry the water away fromthe manhole. Check cables for proper racking, makingsure that they are trained in the proper direction andpositioned so an ample cable radius is left for bends andexpansion/contraction. This radius is basically 5 to 12times the cable diameter, depending on the sheath typeand the number of conductors. Make sure that 6 inchesof straight cable exists for racking on each side of thesplice. Check splices for evidence of leakage ortracking. Look for scrapes, burns, cracks, corrosion, orany other evidence of cable insulation deterioration. Seethat all cables are properly tagged for identification.

Check potheads and terminations that are attachedto risers for leakage, tracking, and evidence ofoverheating or an overvoltage. Also, check the securityof the mounting of the pothead and conduit.

TROUBLESHOOTING CIRCUITS

Troubleshooting of cable systems is much thesame as any other type of electrical troubleshooting.You need a thorough knowledge of the system as wellas the ability to analyze problems. A review of thehistory ofthe system provides clues to present or futuretroubles. Simply using your eyes and head is

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sometimes the most effective method of locating thetrouble. A knowledge of test equipment, an ability toread drawings or schematics, and an understanding ofelectricity are the key factors in locating electricaltroubles.

Types of Trouble

The same basic types of trouble can occur in theairfield lighting cable system whether that system is inseries or in multiple; however, the results of thesecircuit troubles can cause dramatic differences; forinstance, a short circuit across the terminals of adistribution transformer supplying a multiple system isa dangerous overload; and the same short circuit acrossthe output terminals of a CCR and series transformer isa no-load condition. An open in the output circuit of aCCR, on the other hand, creates a dangerous overload.Burned-out lamps in the secondary of a series circuitwill not damage the transformer, but the secondaryvoltage will rise above normal and distort the waveshape ofthe primary current. When enough lamps bumout. the primary current may rise high enough toshorten lamp life and possibly damage the regulator.These critical factors should tell you why you need toknow the circuit.

In the discussion above, all types of electricaltrouble were mentioned; for example, opens, shorts,grounds, and improper power.

OPENS.—An open circuit is an incompletecircuit. Somewhere the circuit has a break;therefore, there is not a complete path for currentflow throughout the circuit. Because there is nocurrent flow, the circuit cannot operate. In analyzingcircuit trouble, if the lights are not burning, themotor is not running, and so forth, you need to lookfor a break in the circuit. Usually this break will be atthe unit(s) of resistance (burned-out lamp, brokenresistor, motor burned out), but sometimes the breakwill happen in the cable. When the cable breaks, thisbreak is most likely to happen at a splice orconnection. Other cable breaks may be caused bydigging operations being done in the wrong place.That occurs when base maps are not kept up to dateand when unauthorized digging operations takeplace. It is an excellent reason for installing andmaintaining direct burial cable markers.

Improper installation of cables can cause them tofail. Cables may be damaged by kinking, bruised byrocks, crushed by wheels, or cut by shovels whenproper care is not exercised during handling and

installation. While the damage at the time it occursmay not be great enough to take the cable out ofservice, it may be the starting point for a cable failure ata later date. This failure may be either in the form of abroken cable (open), cross type of short (two cablestouching), or a short to ground (cable in contact withearth ground). Any of these troubles can render thecircuit inoperative. The indication of the type oftrouble that you have in the circuit and the point in thecircuit where this indication appears should assist youin locating and repairing the circuit.

With an open circuit, that portion of the lightingsystem being supplied by the effected cable will notoperate. A string of lamps that do not light, then, wouldindicate an open cable.

SHORTS.—If lamps are lit when they are notsupposed to be or if a circuit is affected by anothercircuit, you most likely have a cross type of shortbetween the two circuits. The logical point to startlooking for this trouble is where the two cables crossorss where they are close to each other.

GROUNDS.—When a string of lights bums dimor when fuses blow on a circuit, you have a short toground. The insulation on the supply cable is damaged.This defect lets current pass directly from theconductor to the earth and prevents the lamps fromreceiving enough power to operate correctly; that is,some of the resistance of the circuit is being bypassed.The amount of resistance being bypassed in the circuitgoverns the effect of the short to ground. If enoughresistance is removed (bypassed), then the current risesto a point that is sufficient to blow the fuses and thusdisconnect the circuit.

IMPROPER POWER.—Improper power canresult when regulators or distribution transformers arenot connected properly. If the incorrect input voltage isconnected or if the regulator has been purposelyconnected for an unusual load requirement, improperpower can be applied to the system and serious damagemay result.

Underground Lighting Problems

The care and craftsmanship of the originalinstallation will, to a large extent, determine the life ofthe system. Still, no system lasts forever. Even the bestinstallation and the most conscientious inspection andmaintenance program cannot prevent the aging andgradual breakdown of a system. In almost all caseswhen an underground cable breaks down, it goes toground. Where more than one conductor is enclosed in

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one sheath, the insulation within the sheath maydeteriorate so that a cross type of short occurs. Thiscontact almost always creates enough heat andpressure to rupture the sheath and put the conductors incontact with ground.

Moisture is one of the most common causes of anunderground system breakdown. Impurities in thewater help set up corrosion cells, break downneoprene, and rot rubber. Only a trace of moisture,when superheated by the electrical power of the circuitand converted to steam, can cause an explosion thatwill rip the cable to shreds. Groundwater containsenough minerals to provide an excellent conductor toall other parts of the system. Some underground cablesare bonded together. The usual way to find out that anunderground power cable has a problem is to checkwhen the circuit opens.

In ducted systems, the maximum runs betweenmanholes are 500 feet. The normal method of repair isto replace the cable. In direct burial cable systems, the

cable runs may be quite long, and it would beimpractical to replace the entire run. In this case, cablefault locators are used to locate the fault. Beforestarting to work, make sure that all power is off on thecircuits in the trench before you start digging orrepairing the cable.

This chapter does not discuss detailed circuittroubleshooting because each system is different.When you troubleshoot complex problems thatinvolve airfield lighting, you should refer to thefollowing publications: Definitive Designs for NavalShore Facilities, NAVFAC P-272; GeneralRequirements for Shorebased Airfield Marking andLighting, NAVAIR 51-5OAAA-2; and Lighting andMarking Systems for Expeditionary Airfields.NAVAIR 51-4OABA-7. Problems, such as improperpower connections, component connections, safetygrounding, cable splices, cable terminations, and cableinstallations, are discussed in detail in thesepublications.

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CHAPTER 7

ELECTRICAL EQUIPMENT

INTRODUCTION

As a Construction Electrician, you will encountermany pieces of electrical equipment and manyappliances. A solid background in electrical theory andstandards and a working knowledge of the componentsand of the machines themselves will allow you toinstall, maintain, troubleshoot, and repair a widevariety of equipment and appliances.

In one way or another, all machines use the sametechnologies. The differences are in the complexity oftheir operation and the tasks they perform. Thischapter will not cover specific pieces of equipment orappliances but will concentrate on electricalcomponents, motors, controllers, and circuitry that arecommon to most equipment and appliances.

In this chapter you will find many references toarticles, parts, and sections of the National ElectricalCode® (NEC®). You should have an NEC® book onhand while reading this chapter. The chapter text iswritten in general terms. Many of the exceptions givenin the NEC® are not included. Look up the sectionswhen they are referenced. The NEC® can be quiteconfusing, so read the articles closely and pay specialattention to the notes and exceptions.

MOTOR-BRANCH CIRCUITS

A motor-branch circuit is a wiring systemextending beyond the final automatic overloadprotective device. Thermal cutouts or motor overloaddevices are not branch-circuit protection. These aresupplementary overcurrent protection. The branchcircuit represents the last step in the transfer of powerfrom the service or source of energy to utilizationdevices.

MOTOR-BRANCH-CIRCUIT SHORT-CIRCUIT AND GROUND-FAULTPROTECTION (NEC ® 430, PART D)

The Code requires that branch-circuit protectionfor motor circuits must protect the circuit conductors,the control apparatus, and the motor itself againstovercurrent caused by short circuits or grounds(sections 430-51 through 430-58). Fuses or circuit

breakers are the most common protectors used asbranch-circuit protective devices. These protectivedevices must be able to carry the starting current of themotor. To carry this current, they may be rated 300 or400 percent of the running current of the motor,depending on the size and type of motor.

Motor controllers provide motor protectionagainst all ordinary overloads but are not intended toopen during short circuits.

Motor-branch circuits are commonly laid out in anumber of ways. Figures 7-1 through 7-3 show threemotor-branch circuits and how the circuit protection isused in various types of layouts.

As mentioned before, the motor-branch-circuitshort-circuit and ground-fault protective device mustbe capable of carrying the starting current of the motor.For motor circuits of 600 volts or less, a protectivedevice is permitted that has a rating or setting that doesnot exceed the values given in table 430-152 of theCode. An instantaneous-trip circuit breaker (withouttime delay) may be used ONLY if it is adjustable and ispart of a listed combination controller, having motoroverload and also short-circuit and ground-faultprotection in each conductor.

When values for branch-circuit protective devices,as shown in the NEC®, table 430-152, do notcorrespond to the standard sizes or ratings of fuses,nonadjustable circuit breakers, or thermal protectivedevices, you may use the next higher size, rating, orsetting.

The National Electrical Manufacturer’sAssociation (NEMA) has adopted a standard ofidentifying code letters that may be marked by themanufacturers on motor nameplates to indicate themotor kilovoltampere input with a locked rotor. Thesecode letters, with their classification, are given in theNEC®, table 430-7(b). In determining the startingcurrent to use for circuit calculations, use values fromtable 430-7(b). Exceptions to the above are given intable 430-52.

When maximum branch-circuit protective deviceratings are shown in the manufacturer’s overload-relaytable for use with a motor controller or are marked on

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Figure 7-1.—Branch-circuit layout #1.

Figure 7-2.—Branch-circuit layout #2.

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Figure 7-3.—Branch-circuit layout #3.

equipment, you may not exceed them even if highervalues are indicated in table 430-152 of the NEC®;however, you may use branch-circuit protectivedevices of smaller sizes. If you use a branch-circuitdevice that is smaller, you only need to be sure that ithas sufficient time delay to permit the motor-startingcurrent to flow without opening the circuit.

Often it is not convenient or practicable to locatethe branch-circuit short-circuit and ground-faultprotective device directly at the point where thebranch-circuit wires are connected to the mains. Insuch cases, the size of the branch-circuit wires betweenthe feeder and the protective device must be the sameas the mains unless the length of these wires is 25 feet(7.6 meters) or less. When the length of the branch-circuit wires is not greater than 25 feet, the NEC® rulesallow the size of these wires to be such that they havean ampacity not less than one third of the ampacity ofthe mains if they are protected against physicaldamage.

Figure 7-4 gives you an example of branch-circuitconductor sizing, using the figures found in the NEC®

tables 430-152 and 430-7(b).

SEVERAL MOTORS OR LOADS ONONE BRANCH CIRCUIT

You may use a single-branch circuit to supply twoor more motors or one or more motors and other loadsaccording to section 430-53 of the Code. Someexamples are as follows:

1. Several motors, each not exceeding 1horsepower, are permitted on a branch circuit protectedat not more than 20 amperes at 120 volts or less, or at

600 volts or less protected at not over 15 amperes if allof the following conditions can be met:

The rating of the branch-circuit short-circuit andground-fault protective device marked on thecontrollers is not exceeded.

The full-load rating of each motor does notexceed 6 amperes.

Individual overload protection conforms withsection 430-32 of the NEC®.

2. You may connect two or more motors of anyrating to a branch circuit that is protected by a short-circuit and ground-fault protective device selectedaccording to the maximum rating or setting of thesmallest motor.

3. You may connect two or more motors of anyrating and other loads to one branch circuit if theoverload devices and controllers are approved for groupinstallation and if the branch-circuit fuses or circuit-breaker rating is according to section 430-52 of theNEC®.

MOTOR FEEDER SHORT-CIRCUITAND GROUND-FAULT PROTECTION(NEC® 430, PART E)

Overcurrent protection for a feeder to severalmotors must have a rating or setting not greater than thelargest rating or setting of the branch-circuit protectivedevice for any motor of the group plus the sum of thefull-load currents of the other motors supplied by thefeeder.

Protection for a feeder to both motor loads and alighting and/or appliance load must be rated on the

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basis of both of these loads. The rating or setting of theovercurrent device must be sufficient to carry thelighting and/or appliance load plus the rating or settingof the motor branch-circuit protective device.

MOTOR CONTROLLER PROTECTION(NEC® 430, PART G)

A controller is a device that starts and stops a motorby making and breaking the power current flow to themotor windings. A push-button station, a limit switch,or any other pilot-control device is not considered acontroller. Each motor is required to have a suitablecontroller that can start and stop the motor and performany other control functions required. A controller mustbe capable of interrupting the current of the motorunder locked-rotor conditions (NEC® 430-151) andmust have a horsepower rating not lower than therating of the motor, exceptions as permitted.

Branch-circuit fuses or circuit breakers areconsidered to be acceptable controller devices underthe following conditions:

Figure 7-4.—Branch-circuit conductor sizing.

For a stationary motor rated at one-eighthhorsepower or less that is normally left runningand is constructed so that it cannot be damagedby overload or failure to start.

For a portable motor rated at one-thirdhorsepower or less, the controller may be anattachment plug and receptacle.

The controller may be a general-use switch havingan ampere rating at least twice the full-load currentrating of a stationary motor rated at 2 horsepower orless and 300 volts or less.

A branch-circuit breaker, rated in amperes only,may be used as a controller. When this circuit breakeris also used for short-circuit and ground-fault and/oroverload protection, it will conform to the appropriateprovisions of the NEC® governing the type ofprotection afforded. Figure 7-5 will help you tounderstand controller definitions.

Generally, each motor must have its ownindividual controller. The exception is for motors rated600 volts or less; a single controller rated at not lessthan the sum of the horsepower ratings of all of the

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Figure 7-5.—Motor controllers basic rules and exceptions.

motors of the group should be permitted to serve the distance of morethan 50 feet (15.3 meters) is

group of motors under any one of the followingconditions:

Where a number of motors drive several parts ofa single machine or a piece of apparatus, such asmetalworking and woodworking machines,cranes, hoists, and similar apparatus.

Where a group of motors is under the protectionof one overcurrent device, as permitted in NEC®

section 430-53(a).

Where a group of motors is located in a singleroom within sight of the controller location. A

considered equivalent to being out of sight.

DISCONNECTING MEANS, MOTORS, ANDCONTROLLERS (NEC ® 430, PART H)

Each motor, along with its controller or magneticstarter, must have some form of approved manualdisconnecting means, rated in horsepower, or a circuitbreaker. This disconnecting means, when in the OPENposition, must disconnect both the controller and themotor from all ungrounded supply conductors. It mustplainly indicate whether it is in the OPEN or theCLOSED position and may be in the same housing asthe controller.

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For motor circuits of 600 volts or less, thecontroller manual disconnecting means must be withinsight and not more than 50 feet away from the locationof the motor controller. There are two exceptions in theCode rule requiring a disconnect switch to be in sightfrom the controller:

1. For motor circuits over 600 volts, the controllerdisconnecting means is permitted to be out of sight fromthe controller, provided the controller is marked with awarning label giving the location and identification ofthe disconnecting means, and the disconnecting meanscan be locked in the OPEN position.

2. On complex machinery using a number ofmotors, a single common disconnect for a number ofcontrollers may be used. This disconnect may be out ofsight from one or all of the controllers if it is adjacent tothem.

The Code also stipulates that a manualdisconnecting means must be within sight and notmore than 50 feet from the motor location and thedriven machinery. The exception to this rule is that thedisconnecting means may be out of sight if it can belocked in the OPEN position. See figure 7-5 for otherexceptions and basic rules.

The NEC® rules allow a single switch to be thedisconnecting means of a group of motors under 600volts. Also, manual switches or circuit breakers ratedin horsepower can be used as a disconnecting meansand the controller for many motor circuits.

MOTOR AND BRANCH-CIRCUITOVERLOAD PROTECTION(NEC® 430, PART C)

Each continuous-duty motor must be protectedagainst excessive overloads under running conditionsby some approved protective device. This protectivedevice? except for motors rated at more than 600 volts,may consist of fuses, circuit breakers, or specificoverload devices. Overload protection will protect thebranch circuit, the motor, and the motor controlapparatus against excessive heating caused by motoroverloads. Overload protection does not include faultscaused by shorts or grounds.

Each continuous-duty motor rated at more than 1horsepower must be protected against overload by oneof the following means:

1. A separate overload device that is responsive tomotor current. This device is required to be rated or

selected to trip at no more than the following percentageof the motor nameplate full-load current rating:

MOTOR PERCENT

Motors with a marked servicefactor not less than 1.15

125

Motor with a marked tempera- 125ture rise not over 40°C

All other motors 115

For a multispeed motor, each winding connectionmust be considered separately. Modification of thesevalues is permitted. See section 430-34.

2. A thermal, protector, integral with the motor, isapproved for use with the motor that it protects on thebasis that it will prevent dangerous overheating of themotor caused by overload and failure to start. Thepercentages of motor full-load trip current are given insection 430-32 (a-2).

3. A protective device. integral with the motor,that will protect the motor against damage caused byfailure to start is permitted if the motor is part of anapproved assembly that does not normally subject themotor to overloads.

Nonportable, automatically started motors of 1horsepower or less must be protected against runningoverload current in the same manner as motors of over1 horsepower, as noted in section 430-32 (c).

Motors of 1 horsepower or less that are manuallystarted, within sight of the controller location and notpermanently installed are considered protected by thebranch-circuit protective device.

FUSES FOR MOTOR-OVERLOADPROTECTION (NEC ® 430, PART C)

If regular fuses are used for the overload protec-tion of a motor, they must be shunted during thestarting period since a regular fuse having a ratingof 125 percent of the motor full-load current wouldbe blown by the starting current. Many dc-motor andsome wound-rotor-induction-motor installations areexceptions to this rule. Aside from these exceptions, itis not common practice to use regular fuses for theoverload protection of motors. Time-delay fusessometimes can be used satisfactorily for overload pro-tection since those rated at 125 percent of the motorfull-load current will not be blown by the starting

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current. In fact, the manufacturers of these fusesrecommend that for ordinary service. fuses of a smallerrating than 125 percent of the motor full-load currentbe used.

Even time-delay fuses may not be satisfactoryunless they are shunted during the starting periodbecause the 125 percent value cannot be exceeded.

OVERLOAD DEVICES OTHER THANFUSES (NEC® 430, PART C)

The NEC® (table 430-37) indicates the numberand location of overload protective devices, such astrip coils, relays, or thermal cutouts. These overloaddevices are usually part of a magnetic motor controller.Typical devices include thermal bimetallic heaters,resistance or induction heaters, and magnetic relayswith adjustable interrupting and/or time-delaysettings. Overload devices can have a manual orautomatic reset.

THERMALLY PROTECTED MOTORS(NEC® 430, PART C)

Thermally protected motors are equipped withbuilt-in overload protection, mounted directly insidethe motor housing or in the junction box on the side.These devices are thermally operated and protectedagainst dangerous overheating caused by overload,failure to start, and high temperatures. The built-inprotector usually consists of a bimetallic elementconnected in series with the motor windings. Whenheated over a certain temperature, the contacts willopen, thereby opening the motor circuit. On sometypes, the contacts automatically close when cooled, ora reset button must be operated manually to restart themotor.

PROTECTION OF LIVE PARTS(NEC® 430, PART K)

The NEC® requires that live parts be protected in amanner judged adequate to the hazard involved. Thefollowing rules apply:

1. Exposed live parts of motors and controllersoperating at 50 volts or more between terminals must beguarded against accidental contact by enclosure or bylocation as follows:

a. By installation in a room or enclosure acces-sible only to qualified persons

b. By installation on a suitable balcony, gal-lery. or platform so elevated and arranged asto exclude unqualified persons

c. By elevation 8 feet (2.4 meters) or more overthe floor

2. If the live parts of motors or controllers,operating at more than 150 volts to ground, are guardedagainst accidental contact only by location, as specifiedin paragraph I, and if adjustment or other attendancemay be necessary during the operation of the apparatus,suitable insulating mats or platforms must be providedso that the attendant cannot readily touch live partswithout standing on the mats or platforms.

EQUIPMENT GROUNDING

An equipment ground refers to connecting thenoncurrent-carrying metal parts of the wiring systemor equipment to ground. Grounding is done so that themetal parts a person might come into contact with arealways at or near ground potential. With this condition,there is less danger that a person touching the equip-ment will receive a shock.

GROUNDING EQUIPMENT FASTENEDIN PLACE OR CONNECTED BYPERMANENT WIRING METHODS(FIXED) (NEC® 250, PART E)

The word fixed, as applied to equipment requiringgrounding, now applies to equipment fastened in placeor connected by permanent wiring, as shown in figure7-6. That usage is consistently followed in other Codesections also.

The Code requires that all exposed noncurrent-carrying metal parts, such as equipment enclosures,boxes, and cabinets, must be grounded. Equipmentmust be grounded where supplied by metallic wiringmethods; in hazardous locations; where it comes intocontact with metal building parts; in wet, nonisolatedlocations; within reach of a person who is in contactwith a grounded surface; and where operated at over150 volts.

METHODS OF GROUNDING(NEC® 250, PART F)

Section 250-51 sets forth basic rules on the effec-tiveness of grounding. This rule defines the phraseeffective grounding path and establishes mandatoryrequirements on the quality and quantity of conditionsin any and every grounding circuit. The three requiredcharacteristics of grounding paths are very importantfor safety:

1. That every grounding path is permanent andcontinuous. The installer can ensure these conditions by

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Figure 7-6.—Definition of fixed equipment.

proper mounting, coupling, and terminating of theconductor or raceway intended to serve as thegrounding conductor. The installation must be made sothat it can be inspected by an electrical inspector, thedesign engineer, or any other authority concerned. Acontinuity test with a meter, a light, or a bell will assurethat the path is “continuous.”

2. That every grounding conductor has thecapacity to conduct safely any fault current likely to beimposed on it. Refer back to the section of the Code thatspecifically establishes a minimum required size ofgrounding conductor.

3. That the path to ground has sufficiently lowimpedance to limit the voltage to ground and tofacilitate the operation of the circuit protective devicesin the circuit.

USE OF GROUNDED CIRCUITCONDUCTOR FOR GROUNDINGEQUIPMENT (NEC®, SECTION 250-61)

Part (a) of NEC®, section 250-61, permits thegrounded conductor (usually the neutral) of a circuit tobe used to ground metal equipment enclosures andraceways on the supply side of the service disconnect.Figure 7-7 shows such applications. At (A), thegrounded service neutral is bonded to the meterhousing by means of the bonded neutral terminal lug inthe socket. The housing is thereby grounded by thisconnection to the grounded neutral, which itself is

grounded at the service equipment as well as at theutility transformer secondary supplying the service. At(B), the service equipment enclosure is grounded byconnection (bonding) to the grounded neutral, whichitself is grounded at the meter socket and at the supplytransformer. These same types of groundingconnections may be made for cabinets, auxiliarygutters, and other enclosures on the line side of theservice entrance disconnect means, including theenclosure for the service disconnect. At (C),equipment is grounded to the neutral on the line(supply) side of the first disconnect fed from a step-down transformer (a separately derived system).

Aside from the permission given in the fiveexceptions to the rule of part(b) of section 250-61, theCode prohibits connection between a grounded neutraland equipment enclosures on the load side of theservice. So bonding between any system groundedconductor, neutral or phase leg, and equipmentenclosures is prohibited on the load side of the service(fig. 7-8). The use of a neutral-to-ground panelboard orother equipment (other than specified in theexceptions) on the load side of service equipmentwould be extremely hazardous if the neutral becameloosened or disconnected. In such cases, any line-to-neutral load would energize all metal componentsconnected to the neutral, creating a dangerouspotential for electrocution. Hence such a practice isprohibited. This prohibition is fully described in figure7-9.

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Figure 7-7.—Equipment housing ground connections (line side).

Figure 7-8.—Equipment housing ground connections (load side).

Although this rule of the Code prohibits neutral cord or run with the circuit conductors. The conductorsbonding on the load side of the service, sectionsmay be bare or insulated. The insulated conductors250-50(a) and 250-53(b) clearly require such bonding must have a continuous outer finish of green or greenat the service entrance. with one or more yellow stripes.

The circuit conductors used for equipment When the equipment grounding is to begrounding must be within the same raceway, cable, oraccomplished by the protective device of the circuit

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Figure 7-9.—Subpanel bonding hazards.

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conductors, it must be rigid metal conduit,intermediate metal conduit, electrical metallic tubing,flexible metal conduit, type AC cable, or the combinedmetallic sheath and grounding conductors of type MCcable.

Flexible metal conduit is permitted as an equip-ment grounding conductor if the following conditionsare met: the length of the flex does not exceed 6 feet,the circuit conductors within are rated at 20 amperes orless, and the connectors are fittings listed for ground-ing. If the 6 feet of flex is exceeded, a bonding jumperwire, run inside the flex, must be used.

CONTROL CIRCUITS

The subject of electric control circuits is quitebroad. The following text will cover a few of the basiccontrol circuit requirements and controls. For moreinformation, refer to special books devoted to thisimportant phase of motor circuitry. Two such booksare Electric Motor Control by Walter N. Alerich andElectric Motor Repair by Robert Rosenberg andAugust Hand. These textbooks provide an excellentinsight on how to understand, select, and design con-trol circuits.

CONTROL CIRCUITS GENERAL (NEC®

430, PART F and ARTICLE 725)

A control circuit is a circuit that exercises controlover one or more other circuits. These other circuitscontrolled by the control circuit may themselves becontrol circuits, or they may be “load” circuits thatcarry utilization current to a lighting, heating, power,or signal device. Figure 7-10 clarifies the distinctionbetween control circuits and load circuits.

The elements of a control circuit include all theequipment and devices concerned with the function ofthe circuit: conductors, raceway, contactor-operatingcoil, source of energy supply to the circuit, overcurrentprotective devices, and all switching devices thatgovern energization of the operating coil.

Typical control circuits include the operating-coilcircuit of magnetic motor starters, magneticcontactors, and relays. Control circuits include wiringbetween solid-state control devices as well as betweenmagnetically actuated components. Low-voltage relayswitching of lighting and power loads also areclassified as remote-control wiring.

A control circuit is divided into three classes:

Class 1 system may operate at any voltage thatdoes not exceed 600 volts. They are, in many cases,merely extensions of light and power systems, and, witha few exceptions, are subject to all the installation rulesfor light and power systems.

Class 2 and Class 3 systems are those systems inwhich the current is limited to certain specified lowvalues. This limiting may be accomplished by fuses orcircuit breakers, by transformers that deliver only verysmall currents, or by other voltages at which the systemoperates from 5 milliamps or less. All Class 2 and Class3 circuits must have a power source with the power-limiting characteristics described in NEC®, table725-31(a). These requirements are in addition to theovercurrent device.

Conductors for any Class 1 control circuit must beprotected against overcurrent. Number 14 and largerwires must generally be protected at their ampacities.(Review NEC®, table 310-16.) Number 18 andNumber 16 control wires must always be protected at 7and 10 amperes, respectively.

Figure 7-10.—Defining a control circuit.

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Any number and any type of Class 1 circuitconductors may be installed in the same conduit,raceway, box, or other enclosure if all conductors areinsulated for the maximum voltage at which any of theconductors operates and the wires are functionallyassociated with each other.

Class 1 circuit wires may be run in raceways bythemselves according to the NEC®. The number ofconductors in a conduit must be determined fromtables 1 through 5 in chapter 9 of the NEC®).

CONTROL SYMBOLS

In figures 7-11 and 7-12, you see the electrical symbolsthat conform to the standards established by the NationalElectrical Manufacturer’s Association (NEMA). WhereNEMA standards do not exist, American StandardsAssociation (ASA) standards are used; however, not allmanufacturers use these established symbols. In spite of thelack of standardization, knowledge of the symbolspresented in this unit will give you a firm basis forinterpreting variations found in the field.

Figure 7-11.—Standard wiring diagram symbols.

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Figure 7-12.—Standard wiring diagram symbol—Continued.

The control-circuit line diagram of figure 7-13shows the symbol of each device used in the circuit andindicates its function. The push-button station wiringdiagram on the right of figure 7-13 represents thephysical control station and shows the relative positionof each device, the internal wiring, and the connectionswith the motor starter.

line diagrams to develop the ability to interpret thetable quickly and use it correctly; for example, refer tofigure 7-14 and the three-phase column of table 7-1.Note that the control circuit switching is connected toline 1 (L1) and the contactor coil is connected to line 2(L2)

Control WiringControl and Power Connections

Control wiring can be very confusing. A singleoperation of an electrical circuit is usually notcomplicated; however, a sequence of operations, onedepending on the other, in a complex circuit can be

The correct connections and component locationsfor line and wiring diagrams are shown in table 7-1.Compare the information given in the table with actual

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Figure 7-13.—Control circuit components.

Figure 7-14.—Three-phase motor controller diagram.

TWO-WIRE CONTROL. —Two-wire controlprovides no-voltage release or low-voltage release.Two-wire control of a starter means that the starterdrops out when there is a voltage failure and picks up assoon as the voltage returns. In figure 7-15, the pilotdevice is unaffected by the loss of voltage. Its contactremains closed, ready to carry current as soon as linevoltage returns to normal.

difficult to understand. As you already know, most The phrases no-voltage release and two-wireelectrical circuits are represented as a wiring diagramcontrol should indicate to you that an automatic pilotor a line diagram. Work through the examples given device, such as a limit switch or a float switch, opensthroughout this chapter. This practice will improve and closes the control circuit through a single contact.

your skills in reading and understanding electricaldiagrams. If the diagrams are too complex, break themdown to a more elementary diagram. These diagramsare your key to understanding how a machine operatesand how to repair it when it breaks.

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Table 7-1.—Power and Control Connections for Across-the-Line Motor Controllers/Starters

DIRECT SINGLECURRENT PHASE

THREEPHASE

Line markings for. . . . . . . . . . . L1 & L2 L1 & L2 L1, L2, & L3

Overload relay heaters in . . . . . . . . . . . .

Contactor coil connected to . . . . . . . . . . .

L1 L1 T1, T2, & T3

L2 L2 L2

Overload relay contacts in . . . . . . . . . . . . . L2 L2 L2

Control circuits connected to . . . . . . . . . . . . . L1 & L2 L1 & L2 L1 & L2

Control circuit switching connected to. . . . . . L1 L1 L1

Reversing interchange lines. . . . . . . . . . . . . . N/A N/A L1 & L3

Requiring grounding. . . . . . . . . . . . . . . . . . . . L1 is always L1 is always L2ungrounded ungrounded

Figure 7-15.—Two-wire control circuit.

THREE-WIRE CONTROL. —The three-wirecontrol involves the use of a maintaining circuit. Thismethod eliminates the need for the operator to presscontinuously on the push button to keep the coilenergized. Refer to the elementary control circuitdiagram in figure 7-16. When the START button ispressed, coil M is energized across L1 and L2. Thisaction closes contact M to place a shunt circuit aroundterminals 2 and 3. the START button. A parallel circuitis formed with one circuit through push-buttonterminals 2 and 3 and one circuit through contact M.As a result. current will flow through the M coil. Ifpressure is removed from the START button, terminals2 and 3 open. The other circuit through contacts Mremains closed. supplying current to coil M and

maintaining a started-closed position. Such a circuit iscalled a maintaining circuit: a sealing circuit, or aholding circuit.

The phrases no-voltage protection and three-wire control should indicate to the electrician that themost common means of providing this type of controlis a start-stop push-button station.

The main distinction between the two types ofcontrol is that in no-voltage release (two-wire control),the coil circuit is maintained through the pilot-switchcontacts; in no-voltage protection (three-wirecontrol), the circuit is maintained through a stopcontact on the push-button station and an auxiliary(maintaining) contact on the starter.

Figure 7-16.—Three-wire control circuit.

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LOW-VOLTAGE CONTROL. —Sometimes itis desirable to operate push buttons or other controldevices at some voltage lower than the motor voltage.in the control system for such a case. a separate source.such as an isolating transformer or an independentvoltage supply, provides the power to the controlcircuit. This independent voltage is separate from themain power supply for the motor.

One form of separate control is shown in figure7-17. When the thermostat calls for cooling and thehigh-low pressure control is activated, the com-pressor motor starter coil M is energized through thestep-down isolating transformer. When coil M isenergized, power contacts in the 240-volt circuitclose to start the refrigeration compressor motor.Since the control circuit is separated from the powercircuit by the isolating control transformer, there isno electrical connection between the two circuits.For this reason, the wire jumper attached to L2 on astarter should be removed for different voltages;however, the overload relay control contact must beincluded in the separate control wiring.

TROUBLESHOOTING AND TESTINGCONTROLLERS

In this section it is assumed that the motor and fuseare in good condition. To make certain that the motor isnot at fault, connect a voltmeter at the motor terminalsand determine whether voltage is available when thecontacts of the controller are closed. If there is novoltage, the trouble probably, lies in the controller.

Figure 7-17.—Low-voltage control circuit.

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TROUBLESHOOTING

By using a snap-around type of voltmeter-ohmmeter or individual instruments, you can conductmany of the tests needed to determine opens, shorts,grounds. and continuity in just a short time. You cantest malfunctioning circuits for shorted coils; opencoils; grounded coils; open resistances; shortedresistances; low voltages; high voltages: excessiveamperes; broken, loose, or dirty connections; andmany other problems with comparative ease. Thistesting is true of all motors. as well as starters.

You should follow a systematic procedure whentroubleshooting controls.

WARNING

You must exercise extreme caution when test-ing live components. Always use the one-handrule to avoid completing the circuit between thelive component and a metal sur-face. Alwayshave a second person standing by when work-ing on energized equipment and ensure theperson is qualified in CPR. When working onanything that should have the power off, alwaysshut the power off yourself. Most disconnectshave allowances for a padlock to be used tokeep the power from being turned back on. Thissafety precaution is called “LOCKOUT.” TheNAVOSH Manual, OPNAVINST 5 100.23,provides guidance on the Lockout/Tag out pro-gram at shore activi-ties according to OSHAregulations. It is extremely important to takethis precaution. Controls with voltage over 240volts should never be energized when you aretroubleshooting.

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Because there are so many different kinds and makesof controllers, we will outline a genera! procedure forlocating the source of trouble.

1. If the motor does not start when the main con-tacts close, the trouble may be as follows:

a.

b.

c.

d.

e.

f.

g.

Open overload heater coil or poorconnection.

Main contacts not making contact. It is notunusual for one or more contacts to wear tothe degree that they will not make whenclosed. This fault will also occur if thecontacts become dirty, gritty, or burned.

Broken, loose, or dirty terminal connection.

Loose or broken pigtail connection.

Open resistance units or open autotrans-former.

Obstruction of the magnet core, preventingthe contacts from closing.

Mechanical trouble, such as mechanicalinterlocks, gummy pivots, and poor springtension.

2. If the contacts do not close when the STARTbutton is pressed, the trouble may be as follows:

a.

b. Dirty START button contacts or poor contact.

c.

d.

e.

f.

g.

h.

Open holding coil. This can be tested by con-necting a voltmeter across the coil terminalswhen the START button is pressed. If thereis voltage when the START button is pressedbut the coil does not become energized, the coilis defective.

Open or dirty STOP button contacts. If morethan one station is connected to the samecontroller, each station should be checked. IfFORWARD-REVERSE stations are usedand they are interlocked, check all contacts.

Loose or open terminal connections.

Open overload-relay contacts.

Low voltage.

Shorted coil.

Mechanical trouble.

3. If the contacts open when the START button ispressed, the trouble may be as follows:

a. Contacts that do not close completely or aredirty, pitted, or loose.

b. Wrong connection of station to the con-troller.

4. If a fuse blows when the START button ispressed, the trouble may be as follows:

a. Grounded circuits.

b. Shorted coil.

c. Shorted contacts.

5. If the magnet is noisy in operation, the troublemay be as follows:

a. Broken shaded pole causing chattering.

b. Dirty core face.

6. If the magnet coiltrouble may be as follows:

a. . Overvoltage.

is burned or shorted, the

b. Excessive current due to a large magneticgap caused by dirt, grit, or mechanicaltrouble.

c. Too frequent operation.

TESTING COMPONENT CIRCUITS

The example used here is a control that is operatedby a remote switch, such as a float switch. It is assumedthat the device being controlled (a three-phrase motor)is in good working order but is not receiving power.Figure 7-18 shows such a circuit.

The first thing you should check is the line voltage.To do this check, remove the cover of the control boxand test each line with a voltmeter. You should take thevolt readings between L1 and L2, L2 and L3, and thenbetween L3 and L1 . If full voltage is found, you shouldvisually check the power circuit for loose connections.These terminals include L1, L2, L3, T1, T2, and T3.Look for signs of heating at these connections. When aconnection becomes loose, the terminal becomes veryhot; and the screw, wire, and terminal becomediscolored or charred. Check all terminals and tightenthem if necessary. You should only do this checkingand tightening with the power OFF.

Next, check the control circuitry within thecontroller. Do this check by looking at the controlcircuit shown in figure 7-18. The external controls, themagnetic holding coil, and the normally closedoverload contacts are always located between line 1and line 2. Unless the control has been altered, line 3 isnot part of the control circuit. Check also that theexternally located controlling switches, such as the

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Figure 7-18.—Three-phase starter controlled by a floatswitch.

push button, the float, the pressure, or the limitswitches, are connected between line 1 and the holdingcoil. The normally closed overload contacts are alwayslocated between the holding coil and line 2. A wiringdiagram usually can be found in the cover of thecontroller. Now it has been established that the motorand line voltage are in working order. This checkinghas narrowed the problem to the control circuit and thechance that some components are open.

You can locate opens in the control circuit with avoltmeter. Connect one lead of the voltmeter to line 1,and touch the other lead to first one terminal or theholding coil and then the other terminal. There shouldbe the same voltage reading that is read between line 1and line 2. If the control circuit voltage is supplied witha transformer. the voltage read should be that of thetransformer output. If there is no voltage on either sideof the holding coil, the overload contacts are open.Pushing the RESET button should close the overloadcontacts. If they do not close after they have had time tocool. they may be defective. In this case. they should bereplaced.

If there is a voltage on one terminal of the holdingcoil but not the other, the coil is open. You must then

replace the coil. If there is a voltage on both terminalsof the holding coil, the coil and the overload contactscan be assumed to be in working order. To double-check these components, short out line 1 and theterminal marked 3 with a piece of wire. This action willbypass the external control, and then the holding coilshould close the contacts. You can use a current-limiting resistor in place of a w-ire. If the controlfunctions, the problem is in the external controllingdevice.

Solid-state controllers have very complicatedcircuitry; thus, troubleshooting these units requires agood background in electronics and electric motors.These controllers have repair instructions with them aswell as a list of parts that should be stocked for repairpurposes. Repairs consist of replacing boards ormodules that plug into the circuity.

COMBINATION STARTERS

A combination starter consists of a magneticstarter and disconnect switch mounted in the sameenclosure. These starters are supplied with either afused disconnect switch or a circuit breaker. The fuses(or circuit breaker) provide short-circuit protection bydisconnecting the line. A combination starter andcircuit breaker will prevent single phasing bysimultaneously opening all lines when a fault occurs inany one phase. This type of starter can be quickly resetafter the fault has been cleared. Figure 7-19 shows afused combination starter. Figure 7-20 shows acombination starter and a thermal-magnetic circuitbreaker.

PUSH-BUTTON-STATION CONNECTIONS

We will now show you a number of control circuitswith various combinations of push-button stations. A!!of these diagrams use one type of magnetic switch, butothers can be used. Figure 7-21 shows a magneticswitch that is operated from any of three stations.Figure 7-22 shows a straight-line diagram of thecontrol circuit of three start-stop stations. Figure 7-23shows the control circuit of two start-stop stations. Inthese diagrams, the START buttons are connected inparallel, and the STOP buttons are connected in series.These button connections must be done regardless ofthe number of stations. Note that the maintainingcontact is always connected across the START button.All STOP buttons are connected in series with oneanother and in series with the holding coil, so the motorcan be stopped from any position in case of emergency.

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Figure 7-19.—Combination starter with a disconnect switch.

Figure 7-20.—Combination starter with a thermal-magneticcircuit breaker.

START-STOP STATION WITH APILOT LIGHT

Sometimes it is advisable to have a pilot light onthe push-button station to indicate whether the motor isrunning. The lamp usually is mounted on the stationand is connected across the holding coil. Such a con-nection is shown in figures 7-24 and 7-25. Figure 7-26shows a control circuit with the pilot light on when themotor is stopped. Normally closed contacts are neededon this starter. When the motor is running, these con-tacts are open. Contacts are closed when the motor isstopped, and the pilot light goes on.

MOTOR MAINTENANCE

Modern methods of design and construction havemade the electric motor one of the least complicatedand most dependable forms of machinery in existenceand thereby have made the matter of its maintenanceone of comparative simplicity. This statement,however, should not be taken to mean that propermaintenance is not important; on the contrary, it mustbe given careful consideration if the best performanceand longest life are to be expected from the motor. Thetwo major features, from the standpoint of their effectupon the general performance of the motor, are thoseof proper lubrication and the care given to insulation.Lubrication and insulation protect the most vital, andprobably the most vulnerable, parts of the machine.

LUBRICATION

The designs of bearings and bearing housings ofmotors have been remarkably improved. However,this advance in design can cause problems. The bear-ings of modem motors, whether sleeve, ball, or roller,require infrequent attention. In the case of olderdesigns with housings less tight than on modemmachines, oiling and greasing are done frequently. Theperpetuation of this habit causes the oiling andgreasing of new motors to be overdone. The result isthat oil or grease is copiously and frequently applied tothe out-side, as well as the inside, of bearing housings.Some excess lubricant is carried into the machine andlodges on the windings where it catches dirt and there-by hastens the ultimate failure of the insulation.

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Figure 7-21.—Magnetic switch controlled by three start-stop stations.

Figure 7-22.—Control circuit for three start-stop stations.

Figure 7-23.—Control circuit for two start-stop stations.

Greasing Ball Bearings

Only a high grade of grease with the followinggeneral characteristics should be used for ball-bearinglubrication:

1. Consistency, a little stiffer than that ofpetroleum jelly, maintained over the operatingtemperature range

2. Melting point preferably over 150°C

3. Freedom from separation of oil and soap underoperating and storage conditions

4. Freedom from abrasive matter, acid, and alkali

In greasing a motor, you must take care not to addtoo much grease. Overgreasing will cause too high anoperating temperature with resulting expansion andleaking of the grease, especially with large bearingsoperated at slow speeds.

CAUTION

Always review the Material Safety Data Sheet(MSDS) for greases, oils, lubricants, and otherhazardous materials before use. Avoid pro-longed skin contact with lubricants. Dispose ofwaste materials in an environmentallyresponsible manner.

Pressure-Relief Systems

The following procedures are recommended forgreasing ball-bearing motors equipped with apressure-relief greasing system.

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Figure 7-24.—Push-button station with a pilot light.

With a clean screwdriver or similar tool, free therelief hole of any hardened grease so that any excessgrease will run freely from the bearing. With the motorrunning, add grease with a hand-operated pressure gununtil it begins to flow from the relief hole. Thisprocedure tends to purge the housing of old grease.

Figure 7-25.—Control circuit with a pilot light.WARNING

It might prove dangerous to lubricate the motorwhile it is running; follow the procedures withthe motor at a standstill.

Figure 7-26.—Pilot light indicates when motor is not running.

After adding the grease, allow the motor to runlong enough to permit the rotating parts of the bearingto expel all excess grease from the housing. This veryimportant step prevents overgreasing of the bearing.Stop the motor and tightly replace the relief plug witha wrench.

Before pumping grease into the grease fitting,wipe it clean to prevent the grease from carrying dirtinto the fitting and bearing housing. Always removethe relief plug from the bottom of the bearing beforeusing the grease gun. This action prevents applyingexcessive pressure, which could rupture the bearingseals inside the bearing housing.

Motors that are not equipped with the pressure-gunfitting and the relief plug on the bearing housingcannot be greased by the procedures described. Underaverage operating conditions, the factory-packedgrease in the bearing housings of these motors issufficient to last approximately 1 year. When the firstyear of service has elapsed and once a year thereafter(or more often if conditions warrant), you should

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remove the old grease and lubricate the bearings withnew grease. To do this. disassemble the bearinghousings and clean the inside of the housings andhousing plates or caps and the bearings with a suitablesolvent. When you have thoroughly cleansed them ofold grease. reassemble all parts except the outer platesor caps. Apply new grease, either by hand or from atube, over and between the balls. The amount of greaseyou should use varies with the type and frame size ofthe particular motor. You should consult theinstruction sheet that accompanied the motor for thisinformation.

You should add enough grease to fill the bearinghousing one-third to one-half full. Do not use morethan the amount specified. After reassembling themotor, you should refill any V-grooves that are foundin the housing lip with grease (preferably a fibrous.high-temperature-sealing grease) that will act as anadditional protective seal against the entrance of dirt orforeign particles.

Roller Bearings

The technique for greasing motors equipped withroller bearings is quite similar to that used for ballbearings. However, you should follow specificinstructions for the individual design because morefrequent greasing or slight changes in technique maysometimes be necessary.

Sleeve Bearings

With the motor stopped, you periodically shouldcheck the oil level in the sleeve-bearing housings. Ifthe motor is equipped with an oil-filler gauge, thegauge should be approximately three-quarters full atall times.

If the oil is dirty. drain it off by removing the drainplug, which is usually located in the bottom or side ofthe bearing housing. Then flush the bearing with cleanoil until the outcoming oil is clean.

Fractional-Horsepower Motors

In fractional-horsepower motors, there may be nomeans of checking the oil level, as all the oil may beheld in the waste packing. In such cases, a good generalrule for normal motor service is to add 30 to 70 drops ofoil at the end of the first year and to reoil at the end ofeach subsequent 1,000 hours of motor operation.

Most fractional-horsepower motors built todayrequire lubrication once a year. Small fan and agitatormotors often require more frequent lubrication with3-month intervals between oilings.

MOTOR STORAGE

Motors should be stored in a dry, clean place untilready for installation. Heat should be supplied,especially for larger high-voltage machines, to protectthem against alternate freezing and thawing. Thisadvice is equally applicable to spare coils.

Motors that have been in transit in a moistatmosphere or have been idle for an extended periodwithout heat to prevent the accumulation of moistureshould be dried out thoroughly before being placed inservice. Machines also may become wet by accident.or they may sweat as a result of a difference betweentheir temperature and that of the surrounding air. Thiscondition is harmful particularly in the case of large orimportant motors, and should be prevented, by keepingthem slightly warm at all times.

You can pass current at a low voltage through thewindings, use electric heaters, or even use steam pipesfor protective purposes. During extended idle periods,you can stretch tarpaulins over the motor and place asmall heater inside to maintain the proper temperature.

If a motor should become wet from any cause, youshould dry it out thoroughly before operating it again.The most effective method is to pass current throughthe windings, using a voltage low enough to be safe forthe winding in its moist condition.

You can apply heat externally by placing heatingunits around or in the machine and cover the machinewith canvas or some other covering, and then leave avent at the top to permit the escape of moisture. Youcan use small fans to help circulation. You should notallow the temperature of the windings to exceed 100°Cfor Class A insulated motors.

PERIODIC INSPECTION

A systematic and periodic inspection of motors isnecessary to ensure best operation. Of course, somemachines are installed where conditions are ideal; anddust, dirt, and moisture are not present to anappreciable degree. Most motors, however, are locatedwhere some sort of dirt accumulates in the windings,lowering the insulation resistance and cutting downcreepage distance. Dusts are highly abrasive andactually cut the insulation while being carried byventilating air. Fine cast-iron dust quickly penetratesmost insulating materials; hence, you can see whymotors should be cleaned periodically. If conditionsare extremely severe, open motors might require acertain amount of cleaning each day. For less severeconditions. weekly inspection and partial cleaning are

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desirable. Most machines require a completeoverhauling and thorough cleaning out once a year.

BRUSH INSPECTION

Essential for satisfactory operation of brushes isfree movement of the brushes in their holders. Uniformbrush pressure is necessary to assure equal currentdistribution. Adjustment of brush holders should be setso that the face of the holder is approximately oneeighth of an inch up from the commutator; any distancegreater than this will cause brushes to wedge, resultingin chattering and excessive sparking.

Check the brushes to make sure that they will notwear down too far before the next inspection. Keep anextra set of brushes available so that replacements canbe made when needed. Sand in new brushes, and runthe motor without a load to seat the brushes.

Make sure that each brush surface in contact withthe commutator has the polished finish that indicatesgood contact and that the polish covers all contactsurfaces of the brush. Check the freedom of motion ofeach brush in the brush holder. When replacing abrush, be sure to put it in the same brush holder and inits original position. It will be easier for you to replacethe brush properly if you scratch a mark on one side ofthe brush before you remove it.

Check the springs that hold the brushes against thecommutator. Improper spring pressure may lead tocommutator wear and excessive sparking. Excessiveheating may have annealed the springs, in which caseyou should replace them and correct the cause ofoverheating.

COMMUTATOR INSPECTION

Inspect the commutator for color and condition.The part where the brushes ride should be clean andsmooth and should be a polished brown color. A bluishcolor indicates overheating of the commutator.

You should remove any roughness on thecommutator by sandpapering or stoning. Never use anemery cloth or an emery stone. For this operation, runthe motor without load. If you use sandpaper, wrap itpartly around a wooden block. The stone is essentiallya piece of grindstone, known to the trade as a com-mutator stone. With the motor running without load,press the stone or sandpaper against the commutatorwith moderate pressure and move it back and forthacross the commutator surface. If the armature is veryrough, it should be taken out and the commutatorturned down in a lathe.

WARNING

Use care not to come into contact with movingparts.

RECORDS

The electrical shop should have a record card forevery motor. As a minimum, the information on thecard should include inspections, repair work, age, andreplacement stock number.

CLEANING

About once a year or more often if conditionswarrant, motors should be cleaned thoroughly.Smaller motors, the windings of which are not easilyaccessible, should be taken apart.

First, remove the heavy dirt and grease with aheavy, stiff brush; wooden or fiber scrapers; andcloths. You can use rifle-cleaning bristle brushes in theair ducts. You can blow-dry dust and dirt off, usingdry-compressed air at a moderate pressure, perhaps25 to 50-psi pressure at the point of application, takingcare to blow the dirt out and away from the windings. Ifthe dirt and dust are metallic? conducting, or abrasive,using air pressure is not as satisfactory as using asuction system.

CAUTION

When cleaning motors with compressed air,wear safety goggles and hearing protection.Dispose of lubricants and contaminatedmaterials in an environmentally responsiblemanner.

You can easily remove grease, oil, and sticky dirtby applying cleaning liquids specifically designed forthe purpose. These liquids evaporate quickly and, ifnot applied too generously, will not soak or injure theinsulation. If you do use one of these liquids, be sure tofollow the manufacturer’s direction for use.

MOTOR START-UP

After new motors and controls are installed, theyshould be checked for operation under load for aninitial period of at least 1 hour. During this time, theelectrician can observe if any unusual noise or hotspots develop. The operating current must be checkedagainst the nameplate ampere rating. This checkrequires skill in the proper connection, setting, andreading of a clamp-on ammeter. The nameplateampere reading multiplied by the service factor (if any)

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sets the limits of the steady current. This value shouldNOT be exceeded.

Check the power supply against the nameplatevalues; they should agree. Most motors will operatesuccessfully with the line voltage within 10 percent(plus or minus) of the nameplate value or within 5percent of the frequency (hertz). Most 220-volt motorscan be used on 208-volt network systems but withslightly modified performance. Generally, 230-voltmotors should not be used on 208-volt systems.

To reconnect a dual-voltage motor to a desiredvoltage, follow the instructions on the connectiondiagram on the nameplate.

Motor-starter-overload-relay heaters of the propersize must be installed. The motor will not run withoutthem. Sizing information is found inside the controlenclosure cover. The starting fuses should be checkedin a similar manner. The selection of the correct fusesize must be according to the NEC® or localrequirements.

If the motor has not been installed in a clean, well-ventilated place, clean the area. Good housekeeping,as well as direct accident and fire-preventiontechniques, must be emphasized.

Check the motor mounts to be sure that they aresecure and on a firm foundation. If necessary, addgrout to secure the mounts.

Rotate the end shields to place grease fittings,plugs, or any openings in the best, or most accessible,location. Oil or grease the bearings, if necessary.

EQUIPMENT TROUBLESHOOTING

In troubleshooting motors, the first step is to shutdown the machine and lock it out for repair oradjustment. The most valuable troubleshooting asset isyour ability to apply common sense when analyzing acontrol operation. Also, experienced ConstructionElectricians learn to use sensory functions to diagnoseand locate trouble.

LOOKING may reveal contacts stuck and hungup, thereby creating open circuits.

LISTENING may indicate loose parts, faultybearings, excessive speed, and so forth.

SMELLING may indicate burning insulation ora coil failure.

TOUCHING may reveal excessive motor shaftplay, vibration, or normal heat.

Using this seemingly oversimplified procedure tolocate a problem may save you many hours of labor.Consider the length of time it would take to becomethoroughly familiar with a complicated schematicdiagram, compared with locating a few contacts thatare stuck by merely LOOKING.

However, finding a problem in an installation isnot usually this easy. An orderly, step-by-stepapproach is required. Circuit operation is separatedinto logical parts. Circuits and components are thendivided into smaller parts to determine theirfunctions, the relationships to one another, and theeffect that they have on each other in the overallcontrol system operation. Each step leads closer to thesource of the difficulty, finally pinpointing theproblem. This procedure may require the use of avoltage tester, ammeter, multimeter, jumper wires,and other tools.

Check the power supply to see if it is on and if it iscorrect. Test all protective devices. If a coil does notenergize (fig. 7-27), connect a jumper wire from L1 toterminal 3 of the control circuit. By jumping acrossthe contacts of the limit switch and push buttons, youhave separated the circuit operation into logical parts.If the starter coil is now energized, the problem maybe in the limit switch or STOP or START pushbuttons. You now can test smaller circuits and com-ponents by “jumping” around them individually. Testthe limit switch, for example, then go to the controlstation, if necessary.By an orderly process ofelimination accomplished by testing all possible faultareas, you can locate the problem accurately andefficiently.

Figure 7-27.—Start-and-hold control circuit.

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WARNING

Indiscriminate jumping, however, should not bepracticed because of the danger of short circuits.For example, a jumper should never be placedacross a power-consuming device, such as acontactor coil; voltage or ohmmeters testers are

used in this instance. If an ohm-meter is used totest a coil for continuity, the power must beOFF.

Table 7-2 is provided as an aid to servicing elec-tric control equipment. Refer to the table to find thepossible causes of a controller symptom.

Table 7-2.—Controller Troubleshooting Tips

Controller Symptoms

Arcing and burning of contacts

Bellows distorted (on thermally operated devices)

Blowout coil overheats

Breakage, distortion and wear

Breakdown (of static accessories)

Broken flexible shunt

Broken pole shader

Bulbs distorted (on thermallv operated devices)

Burning and welding of control contacts andshunts

Coil failure

Contact opens prematurely

Contact takes longer than normal too open

Contact-tip troubles

a. Filing or dressing

Possible Causes and Recommended Items to Investigate

Should handle very little current and have sealing circuit;misapplied

Mechanical binding; temperature allowed to pass controllimits

Overcurrent; wrong size of coil; loose connections onstud or tip; tip heating; excess frequency

Overheating; mechanical abuse; severe vibration; shock

High temperature; moisture; overcurrent; overvoltage;corrosive atmosphere; mechanical damage; overload; acon dc capacitor; continuous voltage on intermittent types

Large number of operations; improper installation;extreme corrosive conditions; burned from arcing

Heavy slamming caused by overvoltage; weak tippressure; wrong coil; mechanical overload; lowfrequency

Liquid frozen in capillary tube

Shorts circuits on control circuits with too largeprotecting fuses; severe vibration; dirt; oxidation

Moisture; overvoltage; high ambient temperature; failureof magnet to seal in on pickup; too rapid duty cycle;metallic dust; corrosive atmosphere; chattering ofmagnet; wrong coil; holding resistor not cut in;intermittent coil energized continuously; mechanicalfailure; mechanical overload; mechanical underload;handling fluid above rated temperature

Dirt in air gap; shim too thick; too much spring and tippressure; misalignment; not enough capacitance; notenough resistance

Shim too thin; weak spring and tip pressure; gummysubstance on magnet faces; too much capacitance; toomuch resistance

Do not file silver tips; rough spots or discoloration willnot. harm efficiency

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Table 7-2.—Controller Troubleshooting Tips—Continued

b. Interrupting excessively high current Check for grounds, shorts, or excessive motor currents

c. Excessive jogging Install larger device rated for jogging service

d. Weak tip pressure Replace contacts and springs; check carrier for damage

e. Dirt on surfaces Clean contacts; reduce exposure

f. Short circuits or ground fault Remove fault; be sure fuse/breaker size is correct

g. Loose connection Clean then tighten

h. Sustained overload

Corrosion

Check for excessive motor current or install largercontroller

Excess moisture; salt air; acid fumes

Excess wear or friction

Failure to break arc

Failure to hold load

Abrasive dust; high inertia load; excess temperature

Too much current; too much voltage (dc);misapplication; too much inductance

Worn parts; out of adjustment; misapplication; failure touse recommended substitute parts

Failure to make contact

Failure to open or close

Mechanical damage; dirt; corrosive; wear allowancegone

Low voltage; coil open; mechanical binding; mechanicaloverload; no voltage; wrong coil: shorted turns;excessive magnet gap: mechanical binding; gummysubstance on magnet faces: air gap in magnet destroyed;contact tip welded; voltage not removed; corrosion;scale; dirt; operating above rated pressure; damagedmotor

Failure to operate properly

Failure to release

Failure to reset overload relay

Failure to set overload relay

Coils connected wrong; wrong coil; mechanical binding

Improper adjustment; coil not energized; mechanicalbinding: low voltage or current; coil open; shorted turns

Mechanical binding; worn parts; dirt; broken mechanism;corrosion; worn parts; resetting to soon

Improper adjustment; mechanical binding; coil not de-energized; worn parts

Failure to time out (on motor operated relays) Mechanical binding; worn parts; motor damaged; novoltage to motor; dirt

Failure to trip (during overload conditions) Heater incorrectly sized; mechanical binding; relaypreviously damaged by short circuit current; dirt;corrosion; motor and relay in different ambienttemperatures

Fast trip (on overload relays)

Flashover

High temperature; wrong heaters

Jogging; short circuits; handling too large motor;moisture; acid fumes; gases; dirt

Heating Overcurrent; loose connection; spring clips loose orannealed; oxidation: corrosion

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Table 7-2.—Controller Troubleshooting Tips—Continued

High trip Mechanical binding; wrong or shorted coil; assembledwrong

Insulation failure Moisture; acid fumes; overheating; accumulation of dirton surfaces; voltage surges; short circuits; mechanicaldamage; overvoltage

Leaks and mechanical failure (on pneumatic and Corrosion; mechanical damage; excessive pressure; wornhydraulic controllers) seat; solid matter in seat/strainer

Low trip Wrong coil; assembled wrong

Mechanical wear or failure Abrasive dust and dirt; misapplication; mechanicaldamage;excessive operatingspeed

Noisy magnet

Overheating

Pitted, worn, or broken arc-chutes

Broken pole shader; magnet faces not true as result ofwear or mounting strains; dirt on magnet faces; lowvoltage; mechanical overload; improper adjustment (toomuch pressure or incorrect lever ratio)

Incorrect heat rating; running on starter resistor;overload; overvoltage; intermittent-rating deviceoperating too long

Abnormal interrupting duty; excessive vibration orshock; moisture; improper assembly; rough handling

Extra heating from outside; copper oxide on ferrules andclips; high ambient temperature

Overcurrent; moisture; corrosive atmospheres

Premature blowing of protective fuses

Resistor failure (on static accessories)

Short contact life Jogging; handling abnormal currents; lack of lubricationwhere recommended; abrasive dirt

Slow trip (of overload relays) Mechanical binding; dirt; low temperature; wrongheaters

Sticking Dirt; worn parts; improper adjustment; corrosion;mechanical binding

Too slow blowing (of fuse)

Trips too low (on overload relay)

Various mechanical failures

Wrong size fuse for application

Wrong heater; relay in high ambient temperature (motor)

Overvoltage; heavy slamming; chattering; abrasive dust;underload

Wear on magnet Overvoltage; broken pole shader; wrong coil; underload;weak tip pressure; chattering; load out of alignment

Wear on segments or shoes (of a rheostat) Abrasive dust; very heavy duty; no lubrication

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CHAPTER 8

ALARM SYSTEMS

INTRODUCTION

Many buildings and complexes being constructedtoday are equipped with some type of intrusiondetection and fire-alarm systems. You, as aConstruction Electrician, will be challenged to install,troubleshoot, and maintain these systems. Numerousdetection and fire-alarm systems are in existencetoday. In this chapter, we will discuss the function andoperation of a typical detection system and variousfire-alarm systems. When you are in charge of theinstallation or maintenance of either a detection or afire-alarm system, you should acquire referencematerial, such as manufacturer’s literature. If suchmaterial is unattainable, refer to Maintenance of FireProtection Systems, NAVFAC MO-117, that providesan excellent description of several fire-alarm systems.Commercial Intrusion Detection Systems (IDS),Design Manual 13.02, provides descriptions ofvariousintrusion detection systems.

The purpose of any alarm system is either toprotect life or property or to detect an intrusion. Alarmsystems are set up to (1) give early warning sooccupants may evacuate the building and (2) notify thefire department and/or security so they can react assoon as possible.

This chapter will increase your knowledge aboutsecurity/fire-alarm system installation techniques,operations, and maintenance.

INSTALLATION TECHNIQUES

Before the installation of a security/fire-alarmsystem is started, a sketch of the building should beprepared or the original blueprints should be obtained.This sketch should be drawn to scale and should showthe location of all windows and doors, chases, closets,and so forth. A simple riser diagram showing thevarious components, such as smoke and heat sensors,control panel, and alarm signals, should also appear onthe sketch. When this is completed, the installer canbegin the design of the security/fire-alarm system. As aSeabee, it is important to check all supportingdocuments in the manufacturer’s manual before

installing a system. If you encounter a problem,contact the NAVFAC alarm systems coordinator.

TYPES OF FIRE-ALARM SYSTEMS

Building alarm systems may be local or local withbase alarm system connections. They may be coded ornoncoded and may operate either on line-voltage orlow-voltage electric power. Their characteristics aredescribed in the following paragraphs.

Coded Alarm Systems

A coded alarm system has audible or visual alarmsignals with distinctive pulsing or coding to alertoccupants to a fire condition and the location or type ofdevice that originated the alarm. Coding the audibleappliances may help personnel to distinguish the fire-alarm signal from other audible signals. Clear andearly recognition of the signal should encourage amore orderly and disciplined evacuation of thebuilding. A common characteristic of coded alarmsystems, especially of selective coded and multiplexcoded systems, is that the coded alarm identificationprovided by the audible alarm signals is not repeatedcontinuously. Normally, after four completerepetitions of the coded signal, the coding processends.

Noncoded Alarm Systems

A noncoded alarm system has one or more alarm-indicating appliances to alert the building occupants ofa fire but does not tell the location or the type of devicethat has been activated (manual alarm or automaticprotection equipment). The audible or visual alarmappliances operate continuously until they are turnedoff, until a predetermined time has passed, or until thesystem is restored to normal. The location or type ofdevice originating the alarm condition can bedetermined by using an annunciator system. Anannunciator is a visual-indicating device.

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NATIONAL ELECTRICAL CODEREQUIREMENTS FOR SECURITY/FIRE-ALARM SYSTEMS

Because of the potential fire and explosion hazardscaused by the improper handling and installation ofelectrical wiring. certain rules in the selection ofmaterials and quality of workmanship must befollowed as well as precautions for safety,. TheNational Electrical Code® (NEC®) was developed tostandardize and simplify these rules and provide somereliable guide for electrical construction.

The NEC® is published (and frequently revised)by the National Fire Protection Association (NFPA),Batterymarch Park. Quincy, MA 02269. It containsspecific rules and regulations intended to help in thepractical safeguarding of persons and property fromhazards arising from the use of electricity,, includinglow voltage. used in the majority of security/fire-alarmsystems.

Article 725 of the NEC® covers remote-control.signaling, and power-limited circuits that are not anintegral part of a device or appliance. The NEC®

(section 725-1) states:

The circuits described herein (Article 725) arecharacterized by usage and electrical powerlimitations that differentiate them from lightand power circuits and. therefore. specialconsideration is given with regard to minimumwire sizes, derating factors, overcurrentprotection, and conductor insulationrequirements.

Personnel assigned to install security/fire-alarmsystems should become familiar with Article 725 ofthe NEC® as well as Article 760, “Fire ProtectiveSignaling Systems.” This article covers theinstallation of wiring and equipment of fire-protective signaling systems operating at 600 volts orless.

Other NEC® articles of interest to security/fire-alarm installers include the following:

1. Section 300-21, ‘Spread of Fire or Products ofCombustion.”

2. Articles 500 through 516 and Article 517, Part G(dealing with installations in hazardous locations).

3. Article 110, “Requirements for ElectricalInstallations” and Article 300. “Wiring Methods.”

4. Article 310. -“Conductors for General Wiring.”

5. Fire-protectile signaling circuits andequipment will be grounded according to Article 250,except for dc-power limited fire-protective signalingcircuits that have a maximum current of 0.03 amperes.

6. The power supply of nonpower-limited fire-protective signaling circuits will comply with chapters1 through 4 and the output voltage will not be more than600 volts, nominal.

7. Conductors of No. 18 and No. 16 sizes will bepermitted to be used provided they, supply loads that donot exceed the ampacities given in table 402-5 and areinstalled in a raceway or a cable approved for thepurpose. Conductors larger than No. 16 will not supplyloads greater than the ampacities given in tables 310-16through 310-19.

8. When only nonpower-limited fire-protectivesignaling circuits and Class 1 circuits are in a raceway,the number of conductors will be determined accordingto section 300-17. The derating factors given in Note 9to tables 310-16 through 310-19 will apply if suchconductors carry continuous loads.

9. Where power-supply conductors and fire-protective signaling circuit conductors are permitted ina raceway according to section 760-15, the number ofconductors will be determined according to section300-17. The derating factors given in Note 8 to tables310-16 through 310-19 will apply as follows:

a. For all conductors when the fire-protective signaling circuit conductors carrycontinuous loads and the total number of conductorsis more than three.

b. For the power-supply conductors only whenthe fire-protective signaling circuit conductors do notcarry continuous loads and the number of power-supplyconductors is more than three.

10. When fire-protective signaling circuitconductors are installed in cable trays. comply withsections 318-8 through 318-10.

UNDERSTANDING BASICINSTALLATION OF SECURITY/FIRE-ALARM SYSTEMS

The installation of a protective security/fire-alarmcircuit should always start at the protective-circuitenergy source, as if it were an end-of-line battery-abattery. remote from the control panel-even though itmay actually be a power supply installed in the panel.A pair of wires is run from this power source to the firstcontact location, but just the positive wire is cut and

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Figure 8-1.—Contacts are connected into the positive wireonly. Break positive wire only at door contacts.

connected to the two contact terminals, as shown infigure 8-l. The neutral or common wire is not cut butcontinues on in parallel with the positive or “hot” wire.The pair is then run on to the next contact-a door,window, or sensor-and again only the hot wire isconnected to the contacts. This procedure is repeateduntil all contacts are wired in series, and then the pair ofwires is run from the last contact device on the system tothe protective-circuit terminals in the panel. Althoughthe markings will vary from manufacturer tomanufacturer, the terminals for the starting connectionswill read something like LOOP POWER OUT, whilethe terminating terminals will read IN, or a similar term.

Figure 8-2.—Negative conductor is run with a positiveconductor to all contacts, even though the system wouldoperate with just a single-wire, positive-leg wire run from

contact to contact.

A simple circuit of the wiring connections justdescribed is shown in figure 8-2. Obviously, thesystem would operate with just a single-wire,positive-leg circuit run from contact to contact, withthe negative power-supply terminal connecteddirectly to the negative protective-circuit terminalwithin the cabinet. However, manufacturersdiscourage this practice since troubleshooting asingle-wire circuit can be extremely time consuming.and the single wire is more vulnerable to defeat by anintruder with no trouble symptoms occurring to warnthe user of the loss of protection.

An exit/entry delay relay is sometimes used onsecurity systems so that authorized personnel mayexit and enter (using their door keys) withoutactivating the alarm. However, a shunt switch is moreoften preferred (fig. 8-3). The purpose of the shuntlock is to enable an authorized person with a key toshunt out the contacts on the door used for exit/entry,allowing him or her to enter or leave the premiseswithout causing an alarm when the alarm system isturned on. The shunt lock does extend outside theprotected premises; however: it is a potential weaklink in the system. Following the two proceduressuggested below makes defeat of the shunt lock muchmore difficult:

1. Install the shunt lock at the door that is mostbrightly illuminated and most readily visible topassersby.

2. Wire the shunt lock switch to the magneticcontact terminals, as shown in figure 8-4. Thisarrangement traps the lock so that any attempt to pull itout to gain access to its terminals will break thepositive side of the protective circuit and cause analarm to sound.

Contacts used to signal the opening of doors,windows, gates, drawers, and so forth are usuallymounted on the frame of the door or window, while

Figure 8-3.—Typical shunt switch circuit.

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Figure 8-4.—Wire the shunt lock switch to the magneticcontacts as shown.

the magnet unit is mounted on the door or window(moving part) itself. The two units should bepositioned so that the magnet is close to and parallelwith the switch when the door or window is closed.This keeps the shunt lock actuated, but opening thedoor or window moves the magnet away and releasesthe switch mechanism.

As long as the faces of the switch and magnet areparallel and in close proximity when the door orwindow is closed, they may be oriented side-to-side,top-to-top, or top-to-side. Mounting spacers may beused under the units if necessary to improve theiralignment and proximity.

Terminal covers are available for most makes ofdoor contacts to give the installation a more finishedlook and also to protect the terminal connectionsagainst tampering.

The wiring of any alarm system is installed likeany other type of low-voltage signal system; that is,one must locate the outlets, furnish a power supply.and finally interconnect the components with theproper size and type wire.

ALARM SYSTEMS INSTALLED INEXISTING BUILDINGS

Many changes and advances in developingcomplete security/alarm systems for buildingoperation and protection have taken place in the pastfew years. Numerous existing buildings are currentlyhaving security and fire-alarm systems installed eitherto replace their obsolete systems or to provideprotection they never had.

The materials used for installing a complete alarmsystem in an existing building are essentially the sameas those used in new structures. However, the methodsused to install the equipment and related wiring canvary tremendously and require a great deal of skill andingenuity. Each structure is unique.

When concealed wiring is to be installed in afinished existing building. the installation must beplanned so that the Least amount of cutting and

patching is necessary. In most cases, this means givingspecial consideration to the routing of conductors.Unlike the wiring of a new building where the installerwould try to conserve as much material as possible, theamount of material used (within reason) is secondaryin existing buildings. The main objective insecurity/fire-equipment installations in existingbuildings is to install the wiring in the least amount oftime with the least amount of cutting and patching ofthe existing finishes of the building.

Before any actual work on an existing building isstarted, the contractor or the installers should make acomplete survey of the existing conditions in the areaswhere the security system will be installed. If themajority of the work can be done in exposed areas (asin an unfinished basement or attic), the job will berelatively simple. On the other hand, if most of thewiring must be concealed in finished areas, there aremany problems to be solved. The initial survey of thebuilding should determine the following:

1. The best location for the alarm control panel.

2. The type of construction used for the exteriorand interior walls, ceilings, floors, and so forth.

3. The location of any chases that may be used forrouting the conductors and the location of closets,especially those located one above the other for possibleuse in fishing wires.

4. The material used for wall and ceilingfinishes—plaster, drywall, paneling, and so forth.

5. Location of moldings, baseboards, and so forth,that may be removed to hide conductors.

6. Location of decorations or other parts of thebuilding structure that cannot be disturbed.

7. Location of any abandoned electrical racewaysthat new alarm system wires might be fished into. Donot overlook similar possibilities. For example, an oldabandoned gas line can be used to fish security-systemwires in an old building.

8. The location of all doors and windows, coalchutes, and similar access areas to the inside of thebuilding.

As indicated previously, the most difficult task inrunning wires in existing buildings is the installation ofconcealed wiring in finished areas with no unfinishedareas or access to them. In cases like these. the work isusually performed in one of two ways. First bydeliberately cutting the finished work so that the newwiring can be installed. Of course. these damaged

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areas must be patched once the wiring is installed. Thesecond way is to remove a small portion of the finishedarea (only enough to give access to voids in walls,ceilings, etc.) and then fish the wires in. The removedportions of the finished area are then replaced after thewiring is complete.

Where outlet boxes are used, they should bedesigned for installation in the type of finish in thearea. Means of securing the boxes to some structuralmember - l i ke moun t ing ea rs o r ho ld ingdevices-should be given consideration.

Another method of providing outlets in a finishedarea is to remove the existing baseboard and run theconductors in the usual groove between the flooringand the wall and then replace the baseboard. Thismethod requires less work (cutting and patching) thanmost other methods when disturbing a finished area.There is also a type of metal baseboard on the marketthat may be installed along the floor line and used as araceway. Most types are provided with twocompartments for wires: one for power and one forlow-voltage wiring. Using this metal baseboardprovides a simple means of routing wires forsecurity/fire-alarm systems with very little cutting orpatching. In most cases, wires can be fished from thebaseboard up to outlets on the wall, especially if theoutlets are less than 3 feet (0.9 m) above the floor.However, if this is not practical, matching surfacemolding can be installed to blend in very nicely withthe baseboard.

When a lot of cutting and patching is required in afinished area, many installers will have a carpenter dothe work. The carpenter may know some tricks thatwill help the alarm-system installers get the system inwith the least amount of difficulty. Also, any cutting orpatching will be done in a professional manner.

Before doing any actual cutting on an existingbuilding to install security/fire-alarm components, theinstaller should carefully examine the buildingstructure to ascertain that the wires may be routed tothe contacts and other outlets in a relatively easy way.It is possible that a proposed outlet location, forexample, could be moved only a foot or two to takeadvantage of an existing chase. Perhaps a smokedetector or similar component was originally locatedin a ceiling with insulation, which would make thefishing of cables very difficult. If the detector could belocated on a ceiling containing no insulation, the jobwould be greatly simplified.

When cutting holes in ceilings for outlets, youshould spread a drop cloth or paper underneath to catchall dust and dirt. Sometimes an old umbrella can beopened and hung upside down under the spot in theceiling where the hole is being made to catch the debrisand keep it off the rugs and furniture.

Holes for wires and components can be cut throughplaster with a chisel, through wood with a keyhole sawafter first drilling two or four pilot holes, and in brick orother masonry with a masonry chisel or rotaryhammer. To locate the exact spot to cut these openings,first cut a small hole in the center of the spot where thelarger one will be made. This hole may then be used tolocate the area between studs or--in the case of very oldbuildings--the cracks between the plaster laths. It isthen possible to shift the mark for the outlet openingsso that all obstacles can be avoided and the outlet boxor component can be properly anchored.

There are a number of ways to pull and fish wiresinto walls and openings in finished buildings and, witha little ingenuity and careful thought, workers shouldbe able to solve almost any problem of this kind thatthey may encounter.

When you are pulling wires into spaces betweenthe joists in walls, a flashlight placed in the outlet boxhole is often a great help when feeding the wires in orcatching them as they are pushed near the opening.Under no circumstances should a candle or other openflame be used for this purpose. If one must see fartherup or down the inside of a partition, a flashlight and amirror used in combination, as shown in figure 8-5, is agreat help. Many installers like to make their ownmirror by gluing a small 2- by 3-inch (5- by 8-cm)compact mirror on a handle, resembling a woodentongue depressor. Any type of small flashlight may beused.

Figure 8-5.—A flashlight and mirror used in combination are

useful for viewing conditions inside of partitions.

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NEW TECHNIQUES FOR INSTALLINGSECURITY/FIRE-ALARM SYSTEMS INEXISTING BUILDINGS

Presently available are tools that make it mucheasier to install security/fire-alarm systems in existingbuildings. You may now attach a drill bit to a long,flexible spring steel shaft. This makes it possible toeasily manipulate a drill bit in walls to accomplishcomplex installation maneuvers in existing buildings.There are some other tools that are helpful with cableinstallation. An alignment tool may be used to hold thebit and shaft steady while drilling. Line recoverydevices grip the holes located in the shaft end of thedrill, thus, allowing one person to quickly fish wires orcables through partitions and shaft extensions.

Where it becomes necessary. to removefloorboards during a security/fire-alarm installation. itshould be done with the greatest of care so that theedges are not split. On the finished job, when theboards are replaced, split edges make a poorappearance Special saws may be purchased for cuttinginto floors or other surfaces without having to drillholes to start the saw. Then if the tongue (on tongue-and-groove boards) is split off with a thin, sharp chiseldriven down in the crack between the boards, the boardfrom which the tongue was removed can be pried upcarefully without damaging the rest of the floor.

NEW TECHNIQUES AND PROCEDURESFOR OPERATING EQUIPMENT

If at all possible. a reversible drill motor should beused to withdraw the bit from the wall. The motorshould be running only when the bit is actually passingthrough a wood member. When you are drilling, forceis exerted in one direction. When the bit is beingremoved. it is removed at a different angle and force isexerted from a different direction. This is why thereverse is used. If the flexible shaft is being used withdrill motors with no reverse, it would be better to exertforce to pull the bit from the hole with the motorrunning because chances of an easy recovery withoutdamage are much better with the motor running.

When you are drilling from an attic or crawl space,be certain not to select an area directly above or belowa door since this will result in property damage. It isalso good to keep a slight tension on the wire when it isbeing pulled from overhead so that it will not gettangled with the bit and become damaged.

The shaft should not be bowed any more thanabsolutely necessary to accomplish the job. Excessivebowing will decrease the life of the flexible shaft. Drillmotors, of course. should be adequately grounded orelse have insulated handles.

PUTTING NEW TECHNIQUES INTOPRACTICAL APPLICATIONS

Assume that an outlet box for an infraredphotoelectric detector is to be installed above acountertop in a residential kitchen to sense entry ofunauthorized persons through the kitchen door. If.upon investigation of the space inside of the partitions,it is found that a 2- by 4-inch (5- by 10-cm) woodmember (fire stop) blocks the route from the outlethole to the basement area where the alarm controlstation is located, an alignment tool must be used.

The flexible shaft, containing a drill bit. is placedthrough a cut outlet-box opening and then the specialalignment tool is attached to the shaft, as shown infigure 8-6. The shaft will bow back toward the operatorby keeping the alignment tool in the same position tothe shaft and by lifting the handle. As the bit is loweredinto the wall cavity, the operator can feel the bit strikethe inside wall. When the bit is aligned correctly on thewooden member, the alignment tool is removed whilekeeping downward pressure on the bit so that it will notslip out of place, and the hole is drilled through a firestop. This hole will then act as a guide for drillingthrough the floor plate, as shown in figure 8-7.

Figure 8-6.—The alignment tool is attached to the shaft, ready

for operation.

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Figure 8-7.—The first hole cut acts as a guide for drillingthrough the floor plate.

In the case of a wall cavity without tire stops orpurlins, the alignment tool is used to snap the bit backto the inside wail (fig. 8-8) at which time downwardpressure on the drill motor will keep the bit point inplace and cause the shaft to bow. Power and pressureare then transmitted from the back wall that allowsproper angle drilling to miss the joint boxing.

After the bit has penetrated into the basement area,as shown in figure 8-9, the operator has access to thehole in the drill bit itself for attaching the recovery grip

Figure 8-8.—Alignment tool used to snap the bit back to the

inside wall.

Figure 8-9.—Bit has penetrated into basement area.

and pulling the wire up to the outlet location-allwithout damage to existing finishes.

Figure 8-10 shows how the recovery grip isattached to the bit tip eyelet. The swivel, locatedbetween the cable and the head of the grip, prevents thewire or cable from becoming twisted during the fishingprocess.

Figure 8-11 shows the grip after it has beenattached to the bit tip with the line inserted, ready forrecovery. The operator uses the drill motor in reverseand applies a slight pull. The wire then can be pulledeasily through the holes because of the reverse cuttingaction of the bit. If desired, the drill motor can beremoved from the shaft and a recovery grip attached tothe chuck end of the shaft for pulling the wiresdownward toward the basement. While this exampleshows the method of routing wires or cables from anoutlet to a basement, the same procedure would applyfor drilling from an outlet opening to an attic space.

To install contacts on windows for a burglar-alarmsystem, drill from the location of the contact throughthe casement, lintels, and plates with a 3/8-inch (0.9-cm) shaft. Attach a recovery grip to the end of the bit,insert the wire to keep the grip from becoming tangled,reverse the drill motor, and bring the wire toward theoperator as the bit is being withdrawn.

Burglar-alarm contacts or door switches installedat doors are simple projects when one uses the flexibleshaft. First cut or drill the entrance hole in the normalmanner and then insert the flexible shaft with bit into

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Figure 8-10.—Recovery grip attached to the bit tip eyelet.

the entrance hole, slanting the bit as much as possiblein the desired direction of travel. Continue by drillingthrough the door casing and floor jamb into the cavityof the wall, as shown in figure 8-12, view A. A similarprocedure is followed when drilling for windowinstallation as shown in figure 8-12, view B. The drillis then stopped until it strikes the next stud that willdeflect the bit either up or down, depending on thedirection of the drilling. Continue to push the bit until itstrikes the top of the bottom plate and then drillthrough the plate into the basement or attic. Therecovery grip is then attached to the bit and the wire orcable may be drawn back toward the operator byreversing the drill motor and keeping a slight tensionon the wires, as they are being pulled to preventtangling.

With conventional tools, the routing of wires fromone outlet to another, as shown in figure 8-13, requireseither channeling the wall; using wire mold; or runningthe wires down to the baseboard, removing thebaseboard, and then installing the wires behind it.Instances like these occur when the crawl space is tooshallow for workers to crawl into or the house is builton a concrete slab. However, with the flexible shaft, it

Figure 8-11.—Grip attached to the bit tip with the lineinserted, ready for recovery

Figure 8-12.—Drilling through the doorjamb (A) and window casing (B) into the cavity of the wall.

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is possible to drill through the wall horizontallythrough several studs (if the operator is careful) andthen pull the wires back through the holes to theopenings.

The installation of an outside annunciator underthe eave of a house with an extremely low pitch to theroof would cause several problems in getting wires tothe outlet. With the flexible shaft, a hole can be drilledthrough the boxing, as shown in figure 8-14. As soon asthe bit penetrates the boxing, it is pushed into the atticas far as it will go. A recovery grip is then attached tothe bit, the wire or cable inserted, and then pulledbackward toward the outlet opening. The outlet boxand annunciator (horn, bell, etc.) are installed underthe eave and the other end of the cable is connected tothe alarm system. Also, because the flexible shaft ismore rigid than the conventional fish tape, it willpenetrate attic insulation if any exists.

Figure 8-13.—How wires must be routed when one usesconventional tools.

Figure 8-14.—Method of drilling a hole through boxing by

using a flexible shaft.

If it becomes necessary to install wiring in an atticand run cable from this area to the basement, theinstallation can be greatly simplified by using aflexible shaft. First drill through the top plate into thewall cavity, making sure that the drilling is not beingdone above a window or doorway or any otherobstruction, such as existing wiring, ductwork, and soforth. Once through the top plate, the drill motor isturned off and the bit is pushed into the cavity of thewall as far as it will go. If no fire stops are encountered,the bit is pulled back and an extension is attached to theshaft. With the extension installed, the bit is againlowered into the wall cavity until a fire stop isencountered. The bit is then positioned and used to drillthrough the wooden member. Once the woodenmember is penetrated, the drill motor is again stoppedand the bit is lowered further until the bottom plate isreached. Continue drilling through the bottom plate inthe basement or crawl space. Fasten the appropriaterecovery grip, insert the wire or cable, and pull up thewire with the flexible shaft. The drill motor should bereversed only when the bit is passing through one of thewooden members.

Those who use the flexible shaft device often arecertain to discover many other useful techniques forinstalling wiring in existing structures.

COMPONENTS OF SECURITY/FIRE-ALARM SYSTEMS

Wire sizes for the majority of low-voltage systemsrange from No. 22 to No. 18 AWG. However, whenlarger-than-normal currents are required or when thedistance between the outlets is long, it may benecessary to use wire sizes larger than specified toprevent excessive voltage drop. Voltage-dropcalculations should be made to determine the correctwire size for a given application even on low-voltagecircuits.

The wiring of an alarm system is installed like anyother type of low-voltage system. The process consistsof locating the outlets, furnishing a power supply, andfinally interconnecting the components with theproper size and type of wire.

Most closed systems use two-wire No. 22 or No.24 AWG conductors and are color-coded foridentification. A No. 18 pair normally is adequate forconnecting bells to controls if the run is 40 feet (12 m)or less. Many electricians, however, prefer to use No.16 or even No. 14 cable.

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Some of the various components for a typicalsecurity/fire-alarm system are shown in figure 8-15.

CONTROL PANEL

This is the heart of any security system. It is thecircuitry in these control panels that senses a brokencontact and then either sounds a local bell or horn oromits the bell for a silent alarm. Most modem controlpanels use relay type of controls to sense the protectivecircuits and regulate the output for alarm-soundingdevices. They also contain contacts to actuate otherdeterrents or reporting devices and a silent holdupalarm with dialer or police-connected reportingmechanism.

The control unit also continuously. monitors thecondition of the alarm-initiating-and-indicating-circuit wiring and provides a trouble indication in theevent of an abnormal condition in the system, such asan ac power failure or a wiring failure.

The control unit is usually housed in a sheet-metalcabinet (fig. 8-16). The control unit usually providesannunciation of signals (telling where a signaloriginates).

Because all circuits end at the control unit, it is aconvenient test location. Test switches (if provided)

are usually inside the locked door of the control unit. Ifthe switches are key-operated, they may be on thecontrol unit cover, rather than inside the cabinet.

POWER SUPPLIES

Power supplies vary for different systems; but, ingeneral, they consist of rechargeable 6-Vdc powersupplies for burglar-alarm systems. The power packsusually contain nickel-cadmium batteries that are keptcharged by 12-Vac input from a plug-in or otherwiseconnected transformer to a 120-volt circuit. Betterpower supplies have the capability of operating anarmed system for 48 hours or more without beingcharged and still have the capacity to ring an alarm bellfor 30 minutes or longer. Power supplies are obviouslyused in conjunction with a charging source and supplypower for operation of the alarm system through thecontrol panel.

Many older local alarm systems are powered byalternating current (ac) power only with no provisionfor standby, battery power. In these cases, two separateac circuits (usually 120/240 Vac) are used: one topower the fire-alarm system operating circuits andanother to power the trouble-signaling circuits of thesystem. Low-voltage alarm systems, especially, thoseprovided with battery standby power. are most often

Figure 8-15.—Various components for a typical security/fire-alarm system.

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Figure 8-16.—Control unit with annunciation.

found where some form of automatic fire detection orautomatic fire extinguishing is connected to the alarmsystem. However, recent conversion by most alarmsystem manufacturers to solid-state electronic design,which is essentially a low-voltage direct-current (dc)

technology, means that the most recent installationsare of the low-voltage type.

The power supply of the system refers to thecircuitry and components used to convert the ac linevoltage to low-voltage ac or dc for operating the alarmsystem and for charging standby batteries. If thesystem is an older one with a dry cell, nonrechargeablestandby battery (no longer permitted by NFPAstandards), the lower supply probably contains aswitching arrangement for connecting the battery tothe system when ac power fails. Figure 8-17 is asimplified diagram of a typical dc power supply forpowering a low-voltage dc alarm system and forcharging a rechargeable standby battery.

Transformer T drops the line voltage from 120volts ac to a voltage in the range of 12 to 48 volts ac.The low ac voltage is rectified by diode bridge D, andthe resulting dc voltage powers the alarm systemthrough relay contacts S1 and charges battery Bthrough the current limiting resistor R. When normalac power is available energizing relay coil S, contactsS1 are closed. If ac power fails, S1 opens and S2 closes,connecting the battery to the alarm system. Fuse F1protects against a defect in the power supply or thealarm system during normal ac operation. Fuse F2protects against alarm circuits defects that would causea battery overload during dc-powered operation.

Figure 8-17.—Typical dc power supply and battery charger.

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Removal of resistor R eliminates the battery-chargingfeature and allows the use of a dry-cell battery that sitsidle until ac power fails. At that time, S1 pens and S2closes, connecting the battery to the alarm system.

There are many variations of this basic powersupply design. These variations add such features asvoltage regulation, current limiting, and automatichigh-rate/low-rate charging, controlled by the state ofthe battery charge. All designs normally providecurrent and voltage meters, pilot lamps, and switchesfor manual control of charging rate.

ENTRY DETECTORS

The surface magnetic detector is the most versatileentry detector for residential alarm systems and shouldbe considered first as a method of protecting anymovable door or window. These detectors can bemounted on wood, metal, and even glass, if necessary.They can be mounted with screws, double-sided tape,or epoxy. Obviously, the tape and epoxy are useful onglass, aluminum, or any other surface where screwscannot be used. However, when applying tape orepoxy, make certain that the surface is clean, dry,smooth. and at least 65°F (18°C).

Surface-Mounted Magnetic Contacts onDouble-Hung Windows

A switch is mounted on the window casing with amagnet on the window casing and a magnet on thewindow (fig. 8-18). As long as the switch and magnetare parallel and in close proximity when the window is

Figure 8-18.—Double -hung window with surface-mounted

magnetic contacts.

shut, they may be oriented side-to-side, top-to-side, ortop-to-top.

Surface-Mounted Magnetic Contacts on Doors

Where appearance is not the most importantconsideration, the use of a surface-mounted switch (onthe doorframe) and a magnet (on the door) will simplifyinstallation (fig. 8-19).

Recessed Magnetic Contacts in Doors andCasement Windows

Where the appearance of surface-mounted systemsis objectionable, recess-mounted magnetic protectorsmay be used. These detectors are more difficult to installand require greater care on the installer’s part, but fewproblems develop if the following precautions aretaken.

1. Be careful not to damage or destroy anyweatherproofing seal around windows, doors, or otheropenings.

2. If a recessed-mounted entry detector is installedin the windowsill, you must prevent water seepage tothe switch by applying a sealant under the switch flangeand around the switch body.

3. When drilling holes to accept each half of thedetector, be sure the holes line up. Holes are drilled inthe door and in the casing, one directly across from theother, and a pair of wires from the positive side of the

Figure 8-19.—Surface-mounted magnetic contacts on door..

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protective circuits is run out through the switch hole(fig. 8-20). There should be no more than 1/4-inch (0.6cm) space for windows and 1/8-inch (0.3 cm) for doorsbetween the two sections of the detector.

4. Be certain there is enough space between thewindow and its frame (or door and its frame) when eachis closed; that is, there must be enough space (usuallyequaling 1/16 inch or 0.16 cm) for the protrusion of bothsections when they meet.

5. A switch and magnet are installed preferably inthe top of the window and underside of the upperwindow casing, where they will be least noticeable (fig.8-21). If the window frame is not thick enough to acceptthe magnetic section of the detector, the detector can bemounted in the side frame.

Conductive Foil on Glass Doors

A self-adhesive foil block (terminator) on the dooris connected to a similar unit on the doorframe by ashort length of flexible cord to allow for doormovement (fig. 8-22). The foil is connected in thepositive conductor of the protective circuit and isadhered to the glass parallel to and about 3 inches (7.6m) from the edge of the glass, using recommendedvarnish. Breaking the glass breaks the foil and opensthe circuit. A double circuit of foil may be taken fromthe foil block to provide more coverage. Coiled,retractable cords are available for use between foilblocks to allow for sliding-door travel.

Conductive Foil on Picture Window

Where a window does not open, a single run of foilis connected to a foil block on the glass, frame, or wall(fig. 8-23). When the foil crosses over a framemember, a piece of plastic electrical tape should beused to provide an insulated crossover surface for thefoil.

Complete Glass-Door Protection

A glass door with a glass transom may be protectedby a combination of magnetic contacts and foil (fig. 8-24).

Recessed Plunger

The recessed plunger detector shown in figure 8-25 is mounted so that the door or window will contactthe plunger at the tip and push the plunger straight in.Therefore, the area of the window or door thatdepresses the plunger should have no slots, cutouts, orstep-downs into which the plunger might slip. The areaalso should be hard and free of rubber or vinyl thatmight be weakened by the plunger and consequentlyallow the plunger to open. For protecting doors,plunger type of detectors should be mounted only inthe doorframe on the hinge side of the door.

Space Detectors

In cases where it is difficult to protect a window ordoor by mounting any of the direct type of detectors, thearea directly inside the door or window can be protectedwith interior “space” detectors, such as a floor-mat detec-tor (fig. 8-26) or an ultrasonic motion detector (fig. 8-27).

Floor-mat detectors are easily concealed underrugs at doors, windows, top or bottom of stairways, orany other area onto which an intruder is likely to step.Light pressure on the mat triggers the alarm.

There are also rolls of super-thin floor matting thatcan be cut to any desired length. These rolls can be usedon stair treads and in areas near sliding glass doors orother larger glass areas, entrance foyers, and so forth.In households with unrestricted pets, these mats arealmost useless since the pets roam around the homeand are certain to step on one of the mats and trigger thealarm.

Figure 8-20.—Recessed magnetic contacts in door.

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long, by 20 feet (6 m) wide, by 5 feet (2 m) high formost residential models. When an intruder moveswithin the secured area, movement interrupts theestablished pattern of sound waves and sounds thealarm.

Figure 8-21.—Recessed magnetic contacts in casementwindow.

Other space detectors include ultrasonic motiondetectors, audio detectors. and infrared detectors. Caremust be used with any of these units because theprotected area is limited both in width anddepth--depending upon the particular unit.

The ultrasonic motion detector can be used in largeglass-walled rooms that might otherwise be difficult toprotect and in hallways or entries or in virtually anyarea an intruder would have to pass through in movingabout a home or business. They are especially useful asadded protection (when conventional detectors areused also) to monitor a “valuables” room or area.

Most ultrasonic motion detectors are designed formounting on either the wall or ceiling. It emitsinaudible high-frequency sound waves in an ellipticalpattern that ranges from 12 feet (4 m) to 5 feet (11 m)may be used in practically any indoor area or room.

Some designs of motion detectors can be rotatedup to 180° for maximum coverage of the area beingmonitored. as shown in figure 8-28.

Another type of motion detector is the audiodetector (fig. 8-29). This type senses certain sharpsounds known to be present in forced entry, such aswood splintering or glass breaking. When these soundsare received through the miniature microphone of theunit, the detector triggers the control unit to sound analarm.

Audio detectors are best utilized in areas that areseldom used, such as an attic, a garage, or a closed-offwing. They can be used in other areas, but when suchareas are subject to much daytime activity, it isrecommended that the detector only be armed at nightwhen the business is closed or the family retires or isaway from home.

Infrared detectors are another type of motiondetector. A combination transmitter-receiver is used toproject an invisible pulsating beam at a special bounce-back reflector on an opposite wall. Any interruption ofthe beam activates the system alarms. Infrared detectorscan be wired to either the perimeter or interior circuit;but for faster response, it is recommended that it beconnected to the interior circuit.

Infrared detectors are designed for indoor areas,such as entries, hallways, rooms, and so forth. Mostcover a span from 3 feet (1 m) to 75 feet (23 m), so it

Figure 8-22.—Conductive foil on glass doors.

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Figure 8-23.—Conductive foil on picture window.

Figure 8-24.—Complete glass-door protection.

ADDITIONAL COMMERCIAL/INDUSTRIAL COMPONENTS OFSECURITY/FIRE-ALARM SYSTEMS

Industrial security/fire-alarm systems areessentially the same as those used for residentialapplications. There are, however. a few additionalcomponents that are used mostly in industry.

Vibration detectors are often used on industrialbuildings to detect vibrations caused by forced entry.Such detectors have been used on a variety ofconstruction materials. such as hollow tile, plaster andlath, brick, concrete. metal ceilings, and wood. Oncemounted in place, they may be adjusted with a setscrewfor the desired sensitivity.

Some factories maintain a security fence euippedwith fence-guard detectors. This type of dectector willdetect climbing, cutting, or any other penetration of thefenced area. Most of these detectors operate onstandard closed-circuit controls as describedpreviously.

Fence-guard detectors use a vertical-motiondetector that is sensitive to movement created byclimbing or cutting the fence. Normal side motions,such as wind or accidental bumping, do not affect thedetector and cause false alarms. The detectors arenormally mounted about midway up the fence andevery 10 feet (3 m) of fence length. Most of thesedevices set off the alarm if they are tampered with or ifthe wire is cut. They may be connected to a controlpanel and the alarm will sound in the form of a bell orhorn, or it will silently dial the local law-enforcementagency.

Another type of detector that is used is the outdoormicrowave detector. This detector is used for pro-tecting large outdoor areas like car lots, constructionsites, and factory perimeters. In operation, a solid,circular beam of microwave energy extends from atransmitter to the receiver over a range of up to 1,500feet (457 m) for some brands. Any movement inside ofthis beam (fig. 8-30) will activate the alarm.

Thermistor Sensors

The continuous linear thermal sensor is a small-diameter coaxial wire that is capable of sensingtemperature changes along its entire length. The sensoris made up of a center conductor and an outer stainlesssteel sheath. The center conductor is electricallyinsulated from the outer sheath by a ceramic thermistormaterial, as shown in figure 8-31.

Since the thermistor has a negative coefficient ofresistance, the electrical resistance between the centerwire and the outer sheath decreases exponentially, asthe surrounding temperature increases (fig. 8-32).

The changing resistance is monitored by one ofseveral control panels that then can actuateextinguishing systems or any other electricallycontrolled devices.

Such sensors have a diameter of approximately0.080 inch (0.2 cm) and, therefore, have a small massthat permits them to sense changes in temperaturerapidly. They can sense temperatures from 70°F(21°C) up to 1200°F (649°C) if the thermistor materialis properly selected.

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Figure 8-25.—Various components of a residential security/fire-alarm system.

Figure 8-26.—Floor-mat detector.

Since electrical resistance is measured across twowires (center and sheath), the sensor has the ability todetect a high temperature on a short wire as well as alower temperature on a longer one.

The elements are mounted by clamps spaced alongtheir lengths and the detectors, being all solid state,have only two electrical failure modes: open circuitand short circuit. Both of these conditions can becaused only by mechanical means and are minimizedby rigid mounting. Figure 8-33 shows the constructionand mounting details.

Figure 8-27.—Ultrasonic motion detector.

Ultraviolet-Radiation Fire Detectors

Ultraviolet-radiation fire detectors combine large-scale integration circuit techniques with an ultravioletdetection assembly to form a simple, yet flexible, fire-detection system.

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Figure 8-28.—Motion detector rotating up to 180° formaximum coverage.

The basis of this type of system is a gas-detectiontube using the Geiger-Mueller principle to detectradiation wavelengths extending from 2000 to 2450angstroms (Å) (1 Å = 10-8 cm). Figure 8-34 displaysthe radiation sensitive area of the tube and comparesthis area to other forms of radiation. It should be notedthat visible radiation does not extend into the sensitivearea of the detector. Similarly, radiation from artificiallighting sources does not extend into the sensitive areaof the detector.

Figure 8-29.—Audio detector.

Welding arcs and lightning strikes, however, willgenerate radiation to which the detectors are sensitiveand precautions must be taken to minimize theseeffects.

The ultraviolet-radiation detector’s focus ofsensitive points is a 60-degree spherical cone whoseapex lies at the detector tube. Figure 8-35 indicates therelationship between viewing angle and relativesensitivity. The sensitivity of the detector tube is acharacteristic of its cathode material and is fixed, butits voltage-pulse output rate varies both with flame sizeand flame viewing distance. The pulse output rate isdirectly proportional to flame size; that is, it increaseswhen larger flame fronts are presented to the detector.The pulse output rate is also inversely proportional tothe distance of the flame front from the detectortube-the pulse output rate decreases as the distancefrom the detector tube to the flame front increases.

To illustrate, a l-foot (0.09 m2) hydrocarbon firewill cause a pulse output rate of 3 pulses per second at aviewing distance of 30 feet (8 m). This same fire willcause a tube pulse output rate of 20 pulses per second ata viewing distance of 20 feet (6 m). In a like manner, 1-foot (0.09 m2) flame front must be located at a distanceof 5 feet (1.5 m) to create a pulse output rate of 30pulses per second; a 16-foot (1.4 m2) fire will create thesame pulse output rate at a distance of 25 feet (7.6 m),and so forth.

Telephone Dialers

A schematic wiring diagram of a typical telephonedialer is shown in figure 8-36. The two cooperating

8-17

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Figure 8-30.—A solid, circular beam of microwave energy extends from a transmitter to the receiverover a range of up to 1,500 feet (457 m).

Figure 8-31.—Structure of a heat-sensor cable.

channels of the dialer permit two distinct dialing andmessage programs. Although labeled as, and mostcommonly used for, separate burglar and fire alarms thetwo channels can be connected and programmed for anyapplication: medical emergency, heating-systemfailure, freezer warmup, and water-pressure failure.

It is important to understand the priorityrelationship between the two channels before makingtrigger connections. The priority arrangement ensures

Figure 8-32.—Curve showing relationship of resistance totemperature.

transmission of the vital fire-alarm program (or otherpriority program on the FIRE channel) in three ways.

1. If the dialer is already operating on theBURGLAR channel when the FIRE channel istriggered. the dialer immediately switches to FIRE-channel transmission

8-18

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Figure 8-33.—Using connectors to supply desired length of sensor cable.

Figure 8-34.—This detector has maximum sensitivity in the ultraviolet range.

8-19

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Figure 8-35.—Viewing angle of ultraviolet motion detector.

Figure 8-36.—Schematic wiring diagram of a typical telephone dialer.

8-20

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2. When FIRE-channel priority seizure hasoccurred, the dialer overrides its normal end-of-cyclestop and runs for another full cycle. This ensurestransmission of the entire priority program, even if theFIRE-channel take-over occurred near the end of aBURGLAR-channel cycle.

3. Even if the dialer has stopped after transmittingthe full BURGLAR-channel program and the burglar-alarm input is still present, an input on the FIRE channelcauses immediate transmission of the FIRE-channelprogram.

Each of the channels of the dialer can be triggeredby a switched dc voltage, a dry-contact closure, or adry-contact opening. The trigger inputs may be either

momentary or sustained. In either case, the dialertransmits its full program, then stops and resets itself.An input that is still present when the dialer stops mustbe removed briefly and then applied again to restarttransmission on that channel. A sustained input doesnot make the dialer transmit or interfere with normaluse of the telephones, nor does it interfere withtriggering and operation of the dialer on its otherchannel.

When available, an appropriate dry-contactclosure should be used instead of a switched voltagefor the dialer-trigger input. Figure 8-37 shows thepreferred connections for a typical telephonedialer.

Figure 8-37.—Preferred connections for a typical telephone dialer.

8-21

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Where the contacts of a police-connect panel areneeded for polarity reversal, the contacts may be used toprovide a switched-voltage trigger for the dialer, asshown in figure 8-38. This hookup lets the panel’sBELL TEST feature be used without causing any dialertransmission.

When using the bell output of an alarm panel as aswitched-voltage trigger for the dialer, always run the

trigger wires directly from the dialer input terminalsto control the panel terminals. Do not run the wiresfrom the dialer inputs to the bell, horn, or sirenlocations; and do not route the sounding-device wiresthrough the cabinet. Figure 8-39 shows the correctwiring for this hookup. In this hookup, dialerterminals 2, 5, and 6 are connected together withinthe dialer. This permits a simplified three-wiretrigger connection from the control panel.

Figure 8-38.—A switched-voltage trigger connected to a telephone dialer.

Figure 8-39.—Wiring diagram for a switched-voltage trigger.

8-22

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APPENDIX I

REFERENCES USED TO DEVELOPTHE TRAMAN

Although the following references were current when this TRAMANwas published, their continued currency cannot be assured. Whenconsulting these references, keep in mind that they may have been revisedto reflect new technology or revised methods, practices, or procedures. Youtherefore need to ensure that you are studying the latest references.

Chapter 1

Code of Federal Regulation, Title 29, Part 1926; Title 40, Parts 122 and 260-267; U.S. Government Printing Office, Washington, DC, 1997.

Department of the Navy Facility Category Codes, NAVFAC P--72, Naval FacilitiesEngineering Command, Alexandria, VA, 1984.

Environmental and Natural Resources Program Manual, OPNAVINST 5090.1 B,Chief of Naval Operations, Washington, DC, 1994.

Facilities Planning Guide, Volumes 1 and 2, NAVFAC P-437, Naval FacilitiesEngineering Command, Alexandria, VA, 1990.

Facilities Projects Manual, OPNAVINST 11010.20F, Chief of Naval Operations,Washington. DC, 1996.

Hazardous Material Control and Management (HMC&M), OPNAVINST5090.1B, Chief of Naval Operations, Washington, DC, 1989.

Mishap Investigation and Reporting, OPNAVINST 5102.1C, Chief of NavalOperations, Washington, DC, 1989.

Naval Construction Force Occupational Safety and Health Program Manual,COMSECOND/COMTHIRDNCBINST 5100.1, Commander, NavalConstruction Battalions, U.S. Pacific Fleet, Pearl Harbor, HI, and Commander,Naval Construction Battalions, U.S. Atlantic Fleet, Norfolk, VA, 1996.

Naval Mobile Construction Battalion Operations Officer’s HandbookCOMSECOND/COMTHIRDNCBINST 5200.2A, 1989.

Operation and Organizational Maintenance Manual, NAVFAC P-8-628-12, NavalFacilities Engineering Command, Alexandria, VA, 1984.

Procurement. Lease, and Use of Relocatable Buildings, OPNAVINST 11010.33B,Chief of Naval Operations, Washington, DC, 1988.

Seabee Crewleader’s Handbook, The Civil Engineer Corps Officer’s School(CECOS) CBC, Port Hueneme, CA, 1997.

Seabee Planner’s and Estimator’s Handbook, NAVFAC P-405, Naval FacilitiesEngineering Command, Alexandria, VA, 1994.

Table of Advanced Base Functional Components with Abridged Initial OutfittingList, OPNAV 41P3C, Chief of Naval Operations, Washington, DC, 1996.

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Chapter 2

Blueprint Reading and Sketching, NAVEDTRA 12014, Naval Education andTraining Program Management Support Activity*, Pensacola, FL, 1994.

Policy and Procedures for Project Drawing and Specification Preparation MIL-HDBK-1006/1A, Chesapeake Division, Naval Facilities EngineeringCommand, Washington DC, 1995.

Putnam, Robert, Construction Blueprint Reading, Englewood Cliffs, NJ, 1985.

Chapter 3

Croft, Terrell and Wilford I. Summers, American Electrician’s Handbook, 12th ed.,McGraw-Hill, New York, 1992.

Electric Power Distribution Systems Operations, NAVFAC MO-201, NavalFacilities Engineering Command, Alexandria, VA, 1990.

Electric Power Supply and Distribution, TM-5-811-1/AFM 88-9, Chapter 1,Department of the Army and Air Force, Washington, DC, 1984.

Facilities Engineering-Electrical Exterior Facilities, NAVFAC MO-200, NavalFacilities Engineering Command, Alexandria, VA, 1979.

Generator Set, Diesel Engine Drive, Tactical Skid Mount, NAVFAC P-8-628-12,Naval Facilities Engineering Command, Alexandria, VA, 1984.

Introduction to Alternating Current and Transformers, Navy Electricity andElectronics Training Series, Module 2, NAVEDTRA 172-02-00-91, NavalEducation and Training Program Management Support Activity, Pensacola,FL, 1991.

Introduction to Solid-State Devices and Power Supplies, Navy Electricity andElectronics Training Series, Module 7, NAVEDTRA, 172-07-00-92, NavalEducation and Training Program Management Support Activity, Pensacola,FL, 1992.

McPortland, J. F., and Brian J. McPortland, National Electrical Code® Handbook,22nd ed., McGraw-Hill, New York, 1996.

National Electrical Code®, National Fire Protection Association, Quincy, MA,1996.

Chapter 4

Application Guide for Capacitance Current Switching of AC High- Voltage CircuitBreakers Rated on a Symmetrical Current Basis, American National StandardInstitute, Inc., ANSI C37.012-1979(R1989), The Institute of Electrical andElectronics Engineers, Inc., New York.

Electric Power Distribution Systems Operations, NAVFAC MO-201, NavalFacilities Engineering Command, Alexandria, VA, 1990.

Electric Power Supply and Distribution, TM-5-811-1/AFM 88-9, Chapter 1,Department of the Army and Air Force, Washington, DC, 1984.

IEEE Guide for Protection of Shunt Capacitor Banks, American National StandardInstitute, Inc., ANSI C37.99, The Institute of Electrical and ElectronicsEngineers, Inc.. New York, 1990.

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Introduction to Alternating Current and Transformers, Navy Electricity andElectronics Training Series, Module 2, NAVEDTRA 172-02-00-91, NavalEducation and Training Program Management Support Activity, Pensacola,FL, 1991.

Introduction to Solid-State Devices and Power Supplies, Navy Electricity andElectronics Training Series, Module 7, NAVEDTRA, 172-07-00-92, NavalEducation and Training Program Management Support Activity, Pensacola,FL, 1992.

Kurtz, Edwin B., and Thomas M. Shoemaker, The Lineman’s and Cableman’sHandbook, 8th ed., McGraw-Hill, New York, 1996.

McPortland, J. F., and Brian J. McPortland, National Electrical Code® Handbook,22nd ed., McGraw-Hill, New York, 1996.

National Electrical Code®, National Fire Protection Association, Quincy, MA,1996.

Protective Headwear for Industrial Worker-Requirements, American NationalStandard Institute, Inc., ANSI 289.1, New York, 1986.

Rubber Insulating Blankets, American National Standard Institute, Inc., andAmerican Society for Testing and Materials, ANSI/ASTM D1048-88,Philadelphia, 1988.

Rubber Insulating Gloves, American National Standard Institute, Inc., andAmerican Society for Testing and Materials, ANSI/ASTM D120, Philadelphia,1995.

Rubber Insulating Line Hose, American National Standard Institute, Inc., andAmerican Society for Testing and Materials, ANSI/ASTM D1050-90,Philadelphia, 1990.

Specifications and Dimensions of Wood Poles, American National StandardInstitute, Inc., ANSI O5.1, The Institute of Electrical and Electronics Engineers,Inc., New York, 1992.

Chapter 5

Croft, Terrell and Wilford I. Summers, American Electrician’s Handbook, 12th ed.,McGraw-Hill, New York, 1992.

Fink, Donald G., and H. Wayne Beaty, Standard Handbook for ElectricalEngineers, 13th ed., McGraw-Hill, New York, 1993.

Introduction to Alternating Current and Transformers, Navy Electricity andElectronics Training Series, Module 2, NAVEDTRA 172-02-00-91, NavalEducation and Training Program Management Support Activity, Pensacola,FL, 1991.

McPortland, J. F., and Brian J. McPortland, National Electrical Code® Handbook,22nd ed., McGraw-Hill, New York, 1996.

National Electrical Code®, National Fire Protection Association, Quincy, MA,1996.

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Chapter 6

AM-2 Airfield Landing Mat and Accessories, NAVAIR 51-60A-1, Naval AirSystems Command, Washington, DC, 1996.

Definitive Designs for Naval Shore Facilities, NAVFAC P-272, Naval FacilitiesEngineering Command, Alexandria, VA, 1988.

Department of the Navy Physical Security and Loss Prevention, OPNAVINST5530.14B. Chief of Naval Operations, Washington, DC. 1988.

Expeditionary Airfields, NAVAIR 51-35-7, Naval Air Systems Command,Washington, DC. 1984.

Facilities Engineering-Electrical Exterior Facilities, NAVFAC MO-200, NavalFacilities Engineering Command, Alexandria, VA, 1979.

General Requirements for Shorebased Airfield Marking and Lighting, NAVAIR51-50AAA-2, Naval Air Systems Command, Washington, DC, 1990.

Informational Guide for Roadway Lighting, American Association of StateHighway and Transportation Officials, Washington, DC.

Introduction to Fiber Optics, Navy Electricity and Electronics Training Series,Module 24, NAVEDTRA B72-24-00-92, Naval Educational Training ProgramManagement Support Activity, Pensacola, FL, 1992.

Lighting and Marking Systems for Expeditionary Airfields, NAVAIR 51-40ABA-7,Naval Air Systems Command, Washington, DC, 1992.

McPortland, J. F., and Brian J. McPortland, National Electrical Code® Handbook,32nd ed., McGraw-Hill, New York, 1996.

National Electrical Code®. National Fire Protection Association, Quincy, MA,1996.

Standard Practice for Roadway Lighting, American National Standard Institute,Inc.. Illuminating Engineering Society, ANSI/IES RP8-1983(R1993), NewYork.

Chapter 7

Alerich, Walter N., Electric Motor Control, 5th ed., Delmar Publishers Inc.,Albany, NY, 1993.

Code of Federal Regulation, Title 29, Part 1926, U. S. Government Printing Office,Washington, DC, 1997.

Croft, Terrell and Wilford I. Summers, American Electrician’s Handbook, 12th ed.,McGraw-Hill, New York, 1992.

Fink, Donald G., and H. Wayne Beaty, Standard Handbook for ElectricalEngineers, 13th ed., McGraw-Hill, New York, 1993.

Introduction to Solid-Stare Devices and Power Supplies, Navy Electricity andElectronics Training Series, Module 7, NAVEDTRA, 172-07-00-92, NavalEducation and Training Program Management Support Activity, Pensacola,FL: 1992.

McPortland. J. F., and Brian J. McPortland, National Electrical Code® Handbook,22nd ed., McGraw-Hill. New York, 1996.

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National Electrical Code®, National Fire Protection Association, Quincy, MA,1996.

Navy Occupational Safety and Health (NAVOSH) Program Manual, OPNAVINST5100.23D, Chief of Naval Operations, Washington, DC, 1994.

Rosenberg, Robert and August Hand, Electric Motor Repair, 3d ed., SaundersCollege Publishing, Fort Worth, TX, 1987.

Chapter 8

Commercial Intrusion Detection Systems (IDS)DM.l3.02, SN 0525-LP-64-6625,Naval Facilities Engineering Command, Alexandria, VA, 1986.

Introduction to Solid-State Devices and Power Supplies, Navy Electricity andElectronics Training Series, Module 7, NAVEDTRA, 172-07-00-92, NavalEducation and Training Program Management Support Activity, Pensacola,FL, 1992.

Maintenance of Fire Protection Systems, NAVFAC MO-117, Naval FacilitiesEngineering Command, Alexandria, VA, 1989.

McPortland, J. F., and Brian J. McPortland, National Electrical Code® Handbook,22nd ed., McGraw-Hill, New York, 1996.

National Electrical Code®, National Fire Protection Association, Quincy, MA,1996.

Traister, John E., Design and Application of Security/Fire-Alarm Systems,McGraw-Hill, New York, 1990.

* Effective 01 October 1996, the Naval Education and Training ProgramManagement Support Activity (NETPMSA) became the Naval Education andTraining Professional Development and Technology Center (NETPDTC).

AI-5

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INDEX

A

Advanced Base Functional Components (ABFC)assembly 32602, 1-5component P-25, 1-3facility 811 10R, 1-5index of facilities, 1-5NAVFAC P-437, 1-1, 1-2OPNAV 41P3, 1-1ordering, 1-5

Airfield lighting, 6-28circuits, 6-33condenser discharge system, 6-40fixtures and lamps, 6-39layout. 6-28systems, 6-28vault, 6-30

Airfield lighting systems, maintenance, 6-47routine, 6-47troubleshooting circuits, 6-48

Alarm systems, 8-1components, 8-9components, commercial/industrial 8-15control panel, 8-10entry detectors, 8-12equipment operation, new techniques, 8-6fire-alarm systems, 8-1installation, basic, 8-2installation in existing buildings, 8-4installation in existing buildings, new techniques,

8-6installation techniques, 8-1NEC® requirements, 8-2power supplies, 8-10techniques, new, practical application, 8-6

Area lighting systems, see Lighting, areasystems

As-built drawings, see Construction drawings

C

Circuits, motor branch, see Motor branchConduit, bending, 5-15

functions and safety, 5-15power benders, 5-15

Conduit, supports and installation, 5-1 8hangers and supports, 5-19location of supports, 5-18

Construction drawings, 2-2abbreviations and symbols, 2-5

Construction drawings-Continuedas-built drawings, 2-4blueprint language, 2-4dimensions, metric, 2-13dimensions, modular, 2-12lines, types and weights, 2-4scale representation, 2-6schedules, 2-6working sketches, 2-4

Control circuitscontrol symbols, 7-12general, 7-11

Controllerscombination starters, 7-18push-button-station connections, 7-18start-stop station with a pilot light, 7-19testing component circuits, 7-17troubleshooting, 7-16

D

Drawings and specifications, definitions, 2-1Drawings, construction, see Construction

drawings

E

Electrical distribution systems configuration, 4-1loop/ring, 4-1network, 4-2primary selective, 4-3radial, 4-1

Electrical distribution systems maintenance,4-33

digital multimeters, 4-34interference elimination, 4-35maintenance of distributionequipment, 4-35measuring instrument precautions, 4-33safety equipment, 4-36

Electrical distribution systems overheadconsiderations

equipment, 4-4capacitors, 4-15poles, 4-4protective/interrupting devices, 4-20transformers, 4-5pole locations, 4-3protective grounds, 4-25

INDEX-1

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Electrical distribution systems undergroundconsiderations

cable installation, 4-33communication cables, 4-31dangerous gases, 4-33ducts and trenches, 4-29manholes, 4-26power cables, 4-31pulling cable, 4-31rigging, 4-32risers and potheads, 4-30

Electrical safety, 5-24clothing and protective equipment, 5-27fuses, 5-25out-of-service protection, 5-26portable electric tools, 5-25safety color codes, 5-27shock, 5-25

Emergency/standby power, 3-1generating plant operations, 3-6generator installation, 3-4generator selection, 3-1power plant maintenance, 3-11system design, 3-1

Equipment groundingfixed, 7-7grounded circuit conductor, use of, 7-8methods, 7-7

Equipment troubleshooting, 7-24Excavations and shoring

excavations, 1-6shoring, 1-6

F

Fiber-optic measurements, 6-5field measurements, 6-5optical time domain reflectometry, 6-5

Fiber-optic receivers, see Optical detectorsFiber-optic system installation, 6-4Fiber-optic system topology, 6-4Fiber-optical splices, mechanical and fusion 6-6

fusion, 6-8glass or ceramic alignment tube, 6-6multifiber, 6-8rotary, 6-8v-grooved, 6-7

Fiber optics, 6-1optical source properties, 6-1semiconductor LEDs and LDs, 6-1semiconductor material, 6-2transmitters, 6-2

Fire safety, 5-27Fire-alarm systems, see Alarm systems

Floodlights, 6-17aiming, 6-20intensity calculations. 6-25isofootcandle diagrams. 6-23luminaires, selection of. 6-18maintenance factor, 6-35manufacturer’s literature. 6-22mounting height and spacing. 6-19utilization graph. 6-25

G

Generators, see Power generationGrounding equipment. see Equipment grounding

H

Hazardous material, 1-15

I

Interior wiring above grade, 5-4branch circuits for grouped loads. 5-8building wiring, 5-5conductors, 5-8conduit layout, 5-4general provisions. 5-5grounding, 5-5individual branch circuits, 5-8lighting and appliance branch circuit panelboards,

5-6lighting and power systems, 5-6motor branch circuits, 5-8raceway system provisions, 5-5services and feeders, 5-6

Interior wiring below grade, 5-1markings, 5-1underfloor raceway systems, 5-3wet and corrosive installations. 5-1

L

Lighting. airfield, see Airfield lightingLighting, area systems, 6-9

intensity, 6-9intensity calculations. 6-15luminaires, selection of, 6-10manufacturer’s literature. 6-12mounting height and spacing. 6-10street and area classifications, 6-9

Lighting, security, see Security lighting

M

Motor-branch circuits, 7-1disconnecting means. motors, and controllers, 7-5

INDEX-2

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Motor-branch circuits-Continued Qcontrollers, 7-5fuses for motor-overload protection, 7-6 Quality controlmotor controller protection, 7-4 quality control plan, 1-15motor-feeder short-circuit and ground-fault resident officer in charge of

protection, 7-3 construction (ROICC), 1-15overload devices, 7-7overload protection, 7-6 Sprotection of live parts. 7-7several motors or loads, 7-3short-circuit and ground-faultprotection, 7-1thermally protected motors, 7-7

Motor maintenance, 7-19brush inspection, 7-23cleaning, 7-23commutator inspection, 7-23lubrication, 7-19periodic inspection, 7-22records, 7-23storage, 7-22

Motor start-up, 7-23 T

Safety, electrical, see Electrical safetySafety, fire, see Fire safetySecurity lighting, 6-26

alternate power sources, 6-27area classification, 6-27control, 6-27

Soldering and splicing, 5-20solderless connectors, 5-20splices, 5-21

Specifications, 2-2Splices, see Fiber-optical splices

O

Optical detectors and fiber-optic receivers, 6-3Optical fiber splices, see Fiber-optical splices

P

Power generation, 3-1Project planning, 1-7

network analysis, 1-12project planning package, 1-9

Testing electrical circuits, 5-10circuit breakers and fuses, 5-12defective receptacle, 5-10defective switch, 5-10ground terminal, 5-12hot wire, 5-11

Timekeeping, 1-13crew supervisor’s report, 1-14labor accounting system, 1-14reporting, 1-14

INDEX-3

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Assignment Questions

Information: The text pages that you are to study areprovided at the beginning of the assignment questions.

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ASSIGNMENT 1

Textbook Assignment:“Construction Support,” chapter 1, and “Drawings and Specifications,”chapter 2.

1-1. The ABFC system was developed toprovide support facilities to constantlychanging tactical and strategicsituations.

1. True2. False

1-2. Which of the following publications isa detailed, itemized line-item printoutof the material in each ABFC?

1. NAVFAC P-4052. OPNAV 41P3B3. NAVFAC P-4374. NAVFAC P-72

1-3. Which of the following publications isthe basic document that identifies thestructures and supporting utilities ofthe ABFC system?

1. NAVFAC P-4052. OPNAV 41P3B3. NAVFAC P-4374. NAVFAC P-72

1-4. What Facilities Planning Guide givesyou planning information, such as crewsize, man-hours, land area, and fuel?

1. NAVFAC P-437, Vol. I, part III2. NAVFAC P-437, Vol. II3. NAVFAC P-72, Vol. II4. NAVFAC P-72, Vol. I

1-5. Which of the following ABFC seriesprovides the facility code for anelectrical power plant?

1. 2002. 7003. 8004. 900

1-6. The Construction Electrician OrientedAssemblies are grouped into which ofthe following numbered groupings?

1. 10,000 - 19,9992. 20,000 - 29,9993. 30,000 - 39,9994. 40,000 - 49,999

1-7. Verification of stock numbers isautomatically done when components,facilities, or assemblies are ordered.

1. True2. False

1-8. The facility 811 10R ofthemobilization component P25 has twofuel tanks for two 200 kW generators.

1. True2. False

1-9. Which of the following time frames isthe duration of the constructionstandard classified as temporary?

1. less than 6 months2. 6 to 60 months3. 61 to 65 months4. 66 to 70 months

1

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1-10.Days of construction duration arebased on job requirements, optimumconstruction crew size, and full-material availability.

1. True2. False

1-11.An assembly designated code “N” issuitable for which of the followingtemperate zones?

1. North2. Tropical3. South4. Arctic

1-12. Which of the following facilityrecoverability codes indicate a totalrecoverability?

1. A2. B3. C4. D

1-1 3. Trench-excavated materials must NOTbe stored closer than which of thefollowing minimum distances from theexcavated trench edge?

1. 10 feet2. 2 feet3. 6 feet4. 4 feet

1-14. When exiting or entering an excavatedtrench 4 feet or deeper, which of thefollowing methods should be used?

1. Ladder2. Stairway3. Hoist4. All of the above

1-15.Trenches of soft material must beshored if the depth exceeds whatminimum depth?

1. 8 feet2. 6 feet3. 5 feet4. 4 feet

1-16. Which of the following features shouldyou be concerned with whendetermining the angle of slope or thematerial required for safe trenchshoring?

1. Physical condition of the crew2. Depth or cut of the trench3. Anticipated changes in material

from exposure to air, sun, and water4. Both 2 and 3 above

1-17.The project package is the collection ofall information required to plan,schedule, monitor, and execute theproject.

1. True2. False

1-18. Which of the following elements is themost critical part of the projectpackage?

1. Field change documentation2. Project history package3. Project planning package4. Inspection reports and material

availability supply documentation

1-19. After the regiment divides the projectinto master activities and assigns theproject to the battalion, the battalionbreaks down the project intoconstruction activities.

1. True2. False

2

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1-20.Network analysis is used for which ofthe following purposes?

1. As a management tool2. As a method of planning3. As a method of controlling a project4. All of the above

1-21. As a management tool of networkanalysis, what advantage is there inseeing the interdependencies betweenevents and the overall project?

1. Time restraints are easily adjustableto permit changes in the plan

2. Prevents unrealistic or superficialplanning

3. Both 1 and 2 above4. Enables the crew to complete the

project on schedule

1-22. The identification of which of thefollowing events is useful if the projectcompletion date has to be advanced?

1. Critical path2. Manpower scheduling3. Material scheduling4. Equipment scheduling

1-23.Which of the following disadvantagesis common in network analysis of largeprojects?

1. Requirement for a computer2. Chance for error is high when

manually attempting to calculateevents

3. Needs to be revised daily4. Difficult to follow project progresson a day-to-day basis

1-24. Who is responsible for projectplanning?

1. Project crew leader2. Project crew3. Planning and estimating department4. Project manager

1-25. Timekeeping and labor reporting areonly important to NCF units.

1. True2. False

1-26. Labor accounting records aremandatory for man-hours spent onvarious project functions.

1. True2. False

1-27.The accountability for labor expendedincludes work performed by which ofthe following personnel?

1. Military2. Civilian3. Both 1 and 2 above

1-28.Quality control serves which of thefollowing purposes?

1. Prevents discrepancies2. Ensures the quality of workmanship3. Ensures material meets specification

requirements4. All of the above

1-29. Who has responsibility for the qualityof the construction project?

1. Crew leader only2. The chain of command only3. Crew leader and the chain ofcommand4. Project supervisor

3

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Figure 1A

IN ANSWERING QUESTIONS 1-30THROUGH 1-34, REFER TO FIGURE 1A,AND SELECT THE STEP THAT ISDESCRIBED IN THE QUESTION.

4. D

1-34. In what quality control developmentstep would you judge that the work isbeing performed according tospecifications?

1. A2. B3. C

A. Personnel awareness 1-33.In what quality control developmentB. Construction methodsC. Quality control measures about critical measurements and

step would you brief all crew members

D. Work evaluation inspection items?E. Training and equipment requirements

1-30. In what quality control developmentstep would you address specialrequirements, such as training,hazardous material, or personnel safetyprotection?

1. B2. C3. D4. E

1. A2. B3. C4. D

1-31.In what quality control developmentstep would you address concerns aboutproject impact on equipment, tools,materials, labor, training, and safetyrequirements?

1. A2. B3. D4. E

1-35. Who has the final approving author-ifor NCF project field changes?

1. Quality control department2. Quality control chief3. Quality control officer4. Resident officer in charge of

construction1-36.Tight work schedules and adverse

working conditions are acceptablereasons for relaxation of safetystandards.

1. True2. False

1-32. In what quality control developmentstep would you address specializedtraining and special qualifications?

1-37. Project concepts are normallydeveloped by which of the followingactivity/activities?

1. A 1. NAVFACENGCOM2. B 2. Local activities3. C 3. Engineering Field Divisions4. E 4 COMSECOND/COMTHIRD NCB

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1-38.For which of the following reasonsis/are supporting documentation for aconstruction project forwarded toNAVFACENGCOM?

1. Requirement validation2. Technical adequacy of the design3. Reasonable cost estimate4. All of the above

1-39.Project activity quantities provide thebasis for preparing which of thefollowing estimates?

1. Material2. Equipment3. Manpower4. All of the above

1-40. Which of the following information isNOT provided on a project bill ofmaterial statement?

1. Project stock numbers2. Material quantities and line items3. Identification of the location of

where the material will be used4. Description, vendor’s name, and

cost

1-41. Which of the following items containsa precise statement of quantities ofmaterial, equipment, and manpowerrequired to construct a given project?

1. Activity estimate2. Bill of material3. Detailed estimate4. Master activity

1-43. Construction drawings are the mainbasis for defining the requiredactivities, measuring the quantities ofmaterial, and making accurateestimates.

1. True2. False

1-44.Building projects are broadly dividedinto how many major phases?

1. One2. Two3. Three4. Four

THIS SPACE LEFT BLANKINTENTIONALLY.

1-42.The specifications are arranged in thesequence in which the project willprogress.

1. True2. False

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A. WorkingB . S h o pC. PresentationD. PreliminaryE. As bu i l t

Figure 1B

IN ANSWERING QUESTIONS 1-45THROUGH 1-49, REFER TO FIGURE 1B,AND SELECT THE DRAWING THAT ISDESCRIBED IN THE QUESTION.

1-45.What drawing is prepared during thedesign phase?

1. A2. B3. C4. D

1-46. What drawing shows the proposedbuilding or facility in an attractivesetting?

1. A2. B3. C4. E

1-47. What drawing is developed afterapproval has been given forconstruction?

1. A2. B3. C4. D

1-48.What drawing is supplied bymanufacturers to show fabrication ofbuilding parts?

1. A2. B3. D4. E

6

1-49. What drawing provides marked printsthat indicate any constructiondeviations?

1. A2. B3. D4. E

1-50. The drawing index is commonlydivided into how many categories?

1. 102. 83. 64. 4

A. BorderB. Main objectC. TrimD. DimensionE. BrokenF. Equipment

G. ExtensionH. Symbol sectionI. CenterJ. SectionK. Invisible

Figure 1C

IN ANSWERING QUESTIONS 1-51THROUGH 1-61, REFER TO FIGURE 1 C,AND SELECT THE TYPE OF LINEDESCRIBED BY THE QUESTION.

1-5 1. What construction drawing line is alight, continuous line along which thetracing is trimmed to square the sheet?

1. A2. B3. C4. D

1-52. What construction drawing line is aheavy, continuous line that outlines thedrawing?

1. A2. B3. C4. D

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1-53. What construction drawing lineoutlines the main wall lines on plansand sections?

1. A2. B3. C4. D

1-54. What construction drawing line isdrawn between extension lines with anarrowhead on each end?

1. A2. B3. C4. D

1-55. What construction drawing lineextends out from the edge or the pointat which the dimension is to bedetermined?

1. E2. F3. G4. H

1-56. What construction drawing line is alight, continuous, unbroken line usedto show the location of transformers,panels, etc.?

1. E2. F3. G4. H

1-57. What construction drawing line is usedto shade surfaces shown on a drawingand by these means indicate thematerial used?

1. E2. F3. G4. H

1-58. What construction drawing line is usedin detailed drawings where only asection of the object is to be shown?

1. E2. G3. H4. J

1-59. What construction drawing line is usedto indicate an edge(s) that is/are hiddenunder some other part of the structure?

1. E2. I3. J4. K

1-60. What construction drawing line ismade up of alternating long and shortdashes and is used to indicate themiddle of an object?

1. E2. I3. J4. K

1-61. What construction drawing line hasarrowheads at each end that point inthe direction in which the section is tobe taken?

1. E2. I3. J4. K

1-62. Where on a drawing would you findthe meaning of any nonstandardsymbol(s)?

1. Title block2. Legend3. Notes4. Bill of material

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1-63. Which of the following drawing scalesis most commonly used to draw floorplans and elevations of constructionprojects?

1. 1 inch = 1 foot2. l/2 inch = 1 foot3. l/4 inch = 1 foot4. l/8 inch = 1 foot

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ASSIGNMENT 2

Textbook Assignment: “Generators,” chapter 3.

2-1. The National Electrical Code NEC®requires emergency generators andstandby generator systems to be keptentirely separate of all other wiring andequipment.

1. True2. False

2-2. When designing an emergencygenerator backup system, which of thefollowing must comply with electricalsafety standards and codes?

1. Design2. Material3. Installation4. All of the above

2-3. When emergency power replacesnormal power, which of the followingload requirements is powered?

1. Full load2. Maximum capacity of the generator3. Selected loads4. 50% of normal power

2-4. A well-operated active base shouldhave a minimum of which of thefollowing (a) annual load factors and(b) power factors?

1. (a) 25% (b) 95%2. (a) 45% (b) 90%3. (a) 50% (b) 80%4. (a) 50% (b) 75%

2-5.

2-6.

2-7.

2-8.

Lighting circuits will be powered by240 or 208 volt systems.

1. True2. False

When calculating a generator’selectrical load, which of the followingfactors must be determined first?

1. Generator size2. Amount of ampere fluctuation in the

system3. Connected load4. Both 2 and 3 above

The electrical power group maximumdemand determines the size of whichof the following pieces of equipment?

1. Generator2. Conductors3. Electrical apparatus4. All of the above

Which of the following terms is/areknown as the ratio between the actualmaximum demand and the connectedload?

1. Group maximum demand2. Required supply demand3. Demand factor4. All of the above

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2-9. The demand factor is usually less than1.00 for which of the followingreasons?

1. All load devices are seldom in useat the same time

2. All load devices will seldom reachmaximum demand at the same time

3. Some load devices are usuallylarger than the minimum sizeneeded and draw less than theirrated load

4. All of the above

2-10.The total connected load of your repairshop is 60 kW, while the maximumdemand is 40 kW. What is the demandfactor?

1. 26%2. 50%3. 66 %4. 75 %

2-11.Because of noise levels, fire hazards,and air circulation, regulations preventyou from locating a generator closerthan a minimum of how many feet to aload?

1. 252. 203. 154. 10

2-12.A generator supplying power for anadvanced base should be located at the

1. barracks site2. edge of the base3. points of small demand4. points of large demand

2-13.Assume you have the responsibility ofproviding shelter for advanced basegenerators. Before the shelter can beconstructed, you must give the builderall EXCEPT which of the followinginformation?

1. Electrical power load2. Number of generators to be

sheltered3. Size of the generators4. Arrangement of the exhaust system

2-14.One way to get rid of excess engineheat in and around a generator set thatis installed inside a building is by

1. providing suitable exits for exhaustgases

2. opening all the doors and hatcheson the generator set

3. providing large louvered openingsin the side of the generator set

4. providing large louvered openingsin the building walls at the front andback of the generator set

2-15.When installing a generator exhaustsystem you must make sure that thereare no more than three right-anglebends and that the piping is level.

1. True2. False

2-16.Which of the following minimumgenerator exhaust pipe insulationtemperature ratings should you install?

1. 500°2. 1000°3. 1200°4. 1500°

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2-17.Which of the following minimumgenerator ground terminal conductorsize should you use for your generatorinstallation?

1. 4 AWG2. 6 AWG3. 8 AWG4. 10 AWG

2-18.The generator change board facilitatesconversion of which of the followingvoltages?

1. 120/208 only2. 240/480 only3. 120/208 or 240/4804. 120/208 or 240/416

2-19.Positioning of the voltage charge boardconnects two coils of each phase inseries or in parallel.

1. True2. False

2-20.When grounding a generator with asolid metal rod, you must ensure thatthe ground rod complies with which ofthe following requirements?

1. Is embedded below the permanentmoisture level

2. Has a minimum diameter of 5/8inch

3. Is driven to a minimum depth of 8feet

4. Both 2 and 3 above

2-2 1. When grounding a generator with agrounding plate, you must ensure thatthe ground plate complies with whichof the following requirements?

1. Has a minimum of 2 square feet ofsurface area

2. Is buried at a minimum depth of2 l/2 feet

3. Both 1 and 2 above4. Is a minimum of 6 inches thick

2-22. The NEC® states that if you are usinga single ground rod to ground agenerator set, it must have whatmaximum resistance to ground?

1. 25 ohms2. 30 ohms3. 35 ohms4. 40 ohms

2-23. When installing multiple rods or plateelectrodes, they should be installed atwhat minimum distance apart to meetNEC® requirements?

1. 5 feet2. 6 feet3. 8 feet4. 10 feet

2-24. When installing a generator, which ofthe following tests will determine therequired number of ground rods?

1. Conductivity2. Static saturability3. Earth resistance4. Either 2 or 3 above

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2-25.Which of the following factors must be 2-30.Which of the following duties aredetermined before the installation of a performed by personnel on generatorgenerator feeder cable? watch?

1. The size of conductors 1. Operating generator equipment2. Whether conductors will be direct 2. Maintaining generator equipment

burial, overhead, or installed in 3. Keeping the generator operating logconduit 4. All of the above

3. Proper voltage output4. All of the above 2-31.In which of the following logs should

the number of generator operatinghours be recorded?2-26. Concerning generator cable loading,

voltage drop should NOT exceedwhich of the following percentages forcombined power and lighting loads?

1. 6%2. 2%3. 3%4. 5%

2-27.Feeder conductors are capable ofcarrying which of the followingpercentage of rated generator amperes?

1. 100%2. 125%3. 150%4. 200%

2-28.In a traffic area, what is the minimumburial depth for a cable?

1. 18 inches2. 24 inches3. 36 inches4. 48 inches

2-29. Electrical cable may be covered withbackfill (earth) that is free of rocks.

1. Generator fuel log2. Generating station log3. Generator inspection log4. Generator maintenance log

2-32. One purpose for keeping a generatorstation log is to help determine when aparticular piece of equipment needspreventive maintenance.

1. True2. False

2-33. Which of the following requirementsapplies to oily cleaning rags in andaround the generator spaces?

1. They must be stored outside2. They must be stored in a wooden

box that has wooden chips to absorbany oil

3. They must be stored in an oilywaste container that has a cover

4. Either 2 or 3 above

1. True2. False

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2-34.As a generating plant supervisor, youare responsible for which of thefollowing actions?

1. Supervising the activities of theoperating personnel

2. Maintaining a continuous andadequate flow of electrical power

3. Supplementing your knowledge ofthe electrical plans and diagramswith an actual study of thegenerating station’s systems

4. All of the above

2-35.Connecting an electric plant to a de-energized bus involves which of thefollowing actions?

1. Starting the diesel engine andbringing it up to rated speed

2. Operating the switchboard controls3. Both 1 and 2 above4. Aligning the compressed air system

on all electric-start engines

2-36. Which of the following documentscontains the procedure that assures thatall systems and controls are properlyaligned for operation?

1. Prestart checklist2. Operator maintenance manual3. Intermediate maintenance manual4. Shutdown checklist

2-37.Which of the followingdevices/switches adjusts the generatorfrequency?

2-38.Which of the following actions shouldyou take if the load of a singlegenerator becomes so large that itsrating is exceeded?

1. Secure the feed to unnecessary loads2. Install a generator near the greatest

load demand3. Add another generator in parallel4. Implement electrical ration hours

2-39.Before two generators can be operatedin parallel, they must be brought intosynchronism. when they are insynchronism, which of the followingconditions must exist?

1. The terminal voltages must be equal2. The frequencies must be equal3. The voltage sequences must be in

phase4. All of the above

2-40. Which of the following terms describesthe operation of getting a generatorinto synchronism?

1. Synchronizing2. Balancing3. Paralleling4. Equalizing

2-41. Which of the following factors is aprimary consideration in parallelinggenerator sets?

1. Proper division of the load2. Proper division of the speed3. Proper regulation of the speed4. Both 2 and 3 above

1. Voltage regulator2. Governor control3. Synchronizing switch4 Frequency switch

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2-42.Isochronous and speed droop are thetwo types of governor operations youshould be concerned with whenparalleling generators.

1. True2. False

2-43.The isochronous governor willmaintain which of the followinggenerator actions?

1. Load regulation2. Generator capacity3. Output frequency4. Load division

2-44.The number setting on the speed droopknob of a hydraulic governor indicatesthe percentage of droop.

1. True2. False

2-45.On a solid-state electronic governor,when, if ever, are speed droopadjustments necessary?

1. As the load increases2. As the load decreases3. Both 1 and 2 above4. No adjustments are necessary

2-46. When paralleling four generators in thedroop mode, how many generator setswould be in the isochronous position?

1. One2. Two3. Three4. Four

2-47. Concerning generator paralleling, it ispreferable to have the frequency ofwhich of the following generatorsslightly higher than the othergenerators?

1. The largest generator2. The master generator3. Either 1 or 2 above4. The slave generator

2-48.Which of the following actions shouldyou take if the phase sequenceindicating light lights 1-2-3 on themaster generator and 3-2-1 on the slavegenerator?

1. Commence paralleling operations2. Interchange two of the load cables3. Speed up the master generator4. Slow down the slave generator

2-49.When the synchronizing lights blinkON and OFF simultaneously, thisaction indicates which of the followinggenerator conditions?

1. Out of phase2. In phase3. Speed is too fast4. Speed is too slow

2-50.The frequency at which thesynchronizing lights blink ON and OFtogether indicates which of thefollowing circumstances?

1. The frequency of the mastergenerator is out of sync

2. The frequency of the salve generatoris out of sync

3. One generator is out of sync andone generator is in sync

4. The different frequency outputbetween the two generators

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2-51.Conceming generator parallelingoperations using a synchroscope, youshould adjust the frequency of theslave generator until the synchroscopepointer slowly rotates in (a) whatdirection and to (b) what position?

1. (a) Counterclockwise(b) through the zero position

2. (a) Clockwise(b) through the zero position

3. (a) Clockwise(b) through the six o’clock position

4. (a) Counterclockwise(b) through the six o’clock position

2-52.While paralleling using thesynchronizing light, you should closethe main circuit breaker during whichof the following conditions?

1. When lamps are dark2. When lamps are bright3. When one lamp is bright and the

other dark4. Either 2 or 3 above

2-53.The master generator will absorb allload changes and maintain correctfrequency unless it becomesoverloaded or until its load is reducedto zero.

1. True2. False

2-54. The power factor of an electrical loadis determined by dividing the

1. true power by the peak power2. true power by the apparent power3. apparent power by the peak power4. peak power by the average power

2-55. Capacitors may be used to improve thepower factor of the system when thereduced power factor has been causedby effects of which of the followingelectrical factors?

1. Inductive reactance2. Capacitive reactance3. Pure resistance4. All of the above

2-56.You can divide the reactive loadbetween two generators by adjustingthe

1. speed of the generators2. voltage of the generators3. speed droop of the generators4. capacitance-reactance of the voltage

regulators

2-57. Which of the following conditions mayshut down the generator automaticallyand disconnect it from the main load?

1. Engine overspeed2. High jacket water3. Low lubricating oil pressure4. All of the above

2-58. What is the purpose of installing both amechanical clock and an electric clockat the power plant?

1. To ensure correct generator outputfrequency

2. To compensate for power failure3. To ensure correct generator output

voltage4. To indicate improper division of

reactive load

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2-59.Which of the following is NOT arecommended time frame for thegenerator operator maintenanceprogram?

1. Hourly2. Daily3. Weekly4. Monthly

2-60. Of the following maintenance checks,which one is NOT performed by theoperator?

1. Checking the level of the coolant2. Greasing the fuel transfer pump3. Draining water from the fuel tank4. Adding oil to the crankcase

2-61. Which of the following is NOT arecommended time frame for thegenerator preventive maintenanceprogram?

1. Weekly2. Monthly3. Quarterly4. Semiannually

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ASSIGNMENT 3

Textbook Assignment: “Electrical Distribution,” chapter 4, pages 4-1 through 4-33.

3-1.

3-2.

3-3.

What distribution system configurationis the simplest and least expensive tobuild?

1. Radial2. Loop3. Network4. Primary

The loss of which of the followingcomponents in a radial distributionsystem will result in an outage on allloads served by the feeder?

1. Cable2. Primary supply 1. Network3. Transformer 2. Radial4. Each of the above 3. Loop

Service to a radial distribution system 3-7. Which of the following books is ancan be improved by the installation of excellent source of information onwhich of the following components? electrical distribution systems?

1.2.3.4.

Hand reset circuit breakersAutomatic circuit breakersAuto-protected transformersAdditional lightning protectivedevices

3-4. In the loop distribution system, howmany sectionalizing breakers areinstalled near the distributiontransformers to open each primarycable?

1. One2. Two3. Three4. Four

3-5. A network system and a radial systemdiffer in what respect?

1. The ‘type of transformers used2. The type of fuses used3. The way the secondaries are

connected4. The way the primaries are

connected

3-6. If a new primary feeder system must beflexible because of probable futuregrowth, what type of system shouldyou recommend?

1. American Electrician's Handbook2. Standard Handbook for Electrical

Engineers3. The Lineman's and Cableman's

Handbook4. National Electrical Code®

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3-8. Which of the fallowing concerns maybe addresssd when installing a newpower distribution addition?

1. Select the straightest and shortestroute

2. Route the system in the generaldirection of future load demands

3. Make the system readily accessiblefor construction, inspection andmaintenance

4. All of the above

3-9. What type of pole is considered to bethe most economical for power linesupport?

1. Fiberglass2. Steel3. Wood4. Reinforced concrete

3-10. Which of the following means ofdisposal should you use for a creosote-treated wooden pole?

1. Burning2. EPA approved landfill3. Burying4. Either 2 or 3 above

3-11. Which of the following means is usedto classify a wooden pole?

1. Length2. Circumference at the top of the pole3. Circumference measured 6 feet

from the bottom of the pole4. All of the above

3-12. Lightning arresters for a distributiontransformer should be located betweenwhich of the following areas?

1. Primary mains and fuse cutouts2. Primary and secondary sides of the

transformer3. Fuse cutouts and the secondary

bushings of the transformer4. Secondary side of the transformer

and the service drop

3-1 3. Which of the following types ofdistribution transformers require theinstallation of external protectivedevices?

1. Conventional2. Self-protected3. Both 1 and 2 above4. Completely self-protected

3-14. What feature does the completely self-protected (CSP) type of transformerhave that differs from the other types?

1. A built-in circuit breaker2. A fuse cutout mounted to the

outside of the transformer3. A beeper that sounds when there’s

trouble within the transformer4. Two tap changers: one primary and

one secondary

3-15. How much oil should be put in atransformer?

1. Fill up to the rim2. Standard 5 gallons3. Fill up to the oil-level line4. Add as much oil as needed to cover

the secondary coils only

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A. Liquid-immersed water-coolingB. Liquid-immersed self-coolingC. Air-blast coolingD. Self-air cooling

3-19. This transformer has a cooling methodthat has its coils and core completelyimmersed in transformer oil.

Figure 3A

IN ANSWERING QUESTIONS 3-16THROUGH 3-19, REFER TO FIGURE 3A,AND SELECT THE TRANSFORMERDESCRIBED IN THE QUESTION.

1. A2. B3. C4. D

3-20. Which of the following types oftransformers would you find in a majorsubstation?

3-16. This transformer has a cooling methodthat cools by surrounding air atatmospheric pressure.

1. A2. B3. C4. D

3-17. This transformer has a cooling methodthat has the core and windings encasedin a metal enclosure through which airis circulated by a blower.

1. A2. B3. C4. D

1. Completely self-protected (CSP)2. Current3. Air-blast-cooling4. Auto

3-21. Old transformers may contain which, ifany, of the following dangerouschemical elements?

1. CO2R2

2. PCBs3. CO2H2

4. None

3-22. Which of the following safetyprecautions will protect you whenhandling Askarel® oil?

3-18. This transformer has a cooling method 1. Wearing impermeable glovesthat has water circulated through coils 2. Wearing splashproof gogglesand carries away the heat from the oil 3. Properly ventilating the work spaceas it rises in the tank. 4. All of the above

1. A2. B3. C4. D

3-23. When removing Askarel® oil that iscontaminated with PCBs, an airrespirator may be necessary,

1. True2. False

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3-24. The ground resistance between the 3-29. When determining the size of aground wire and the ground transformer for a certain load, howdistribution neutral should read no should you calculate the approximatemore than how many ohms? maximum demand load?

1. 102. 253. 504. 66

3-25. Which of the following actions willlower ground resistance?

1. Drive additional ground rods2. Connect additional ground rods in

parallel3. Use larger ground rods4. All of the above

3-26. Which of the following terminalmarkings is correct for a transformerwith additive polarity?

1. H2H1-X1X22. H1H2-X2X13. Both 1 and 2 above4. H1H2-X1X2

3-27. Transformers larger than 100 kVA areusually mounted on which of thefollowing places?

1. Pad or platform2. Pole below the secondary mains3. Pole above the secondary mains4. Cluster mount above the primary

mains

3-28. At what height above the base of thepole are ground wires required to becovered with plastic or wood molding?

1. Divide the total maximumconnected load by the demandfactor

2. Divide the demand factor by thetotal maximum connected load

3. Multiply the total maximumconnected load by the demandfactor

4. Multiply the total maximumconnected load by the power factor

3-30. Power capacitors are used indistribution systems to supply whatelectrical factor?

1. Capacitive reactance2. Inductive reactance3. Reactive voltamperes4. Impedance

3-31. When voltage and current waves do nothave the same direction at the sameinstant they are said to be

1. in phase2. out of phase3. lagging phase4. leading phase

3-32. When current and voltage in a circuitrise and fall in value together, in thesame direction at the same instant,what is the power factor in that circuit?

1. Zero2. .753. .804. 1.01. 6 feet

2. 8 feet3. 10 feet4. 12 feet

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3-33. What is the unit of measurement for 3-38. What happens when a capacitor isapparent power? operated below its rated frequency?

1. ohms2. Watts3. Voltamperes4. Watts per voltamperes

1. kvar rating is reduced2. kvar rating is increased3. Current is reduced4. Voltage is reduced

3-34. What is the cause of low power factorin an electrical circuit?

1. High load resistance2. Low impedance3. High amount of inductance4. Low inductive reactance

3-35. Which of the following electricalcomponents is used for power factorcorrection?

3-39. Other than for power factor correction,a capacitor in an electrical distributionsystem can be used for which of thefollowing purposes?

1. Current boost during heavy loads2. Voltage boost during heavy loads3. Current boost when the power

factor is low4. Voltage boost when the power

factor is low

1. Booster transformer2. Filter resistor3. Inductive filter4. Synchronous motor

3-40. After a capacitor has beendisconnected from an energized circuit,how long should you wait beforeconnecting it back to the circuit?

3-36. What device is most economical tocorrect a low power factor?

1. Synchronous motor2. Capacitor3. Inductor4. Filter resistor

3-37. Capacitance is the opposite of whatelectrical factor?

1. Resistance2. Impedance3. Conductance4. Inductance

1. 1 hour2. 1 l/2 hours3. 5 minutes4. 15 minutes

3-41. Before shorting the terminals of acapacitor, which of the followingprecautions should you follow?

1. Wait 15 minutes2. Make sure the capacitor voltage is

zero3. Make sure the terminals are

grounded to earth4. All of the above

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3-42. When a capacitor is installed to switcha circuit on and off, the switchingdevice should be rated at whatpercentage of the capacitor rating?

1. 80%2. 100%3. 125%4. 135%

3-43. Capacitors rated at 600 volts or morewith built-in discharge resistors arerequired by the National ElectricalCode® to be discharged in 5 minutesto what minimum voltage?

1. 5 volts2. 15 volts3. 50 volts4. 100volts.

3-44. Primary capacitors used in distributionsystems are rated at what minimumvoltage?

1. 600 volts2. 1,000 volts3. 2,400 volts4. 3,000 volts

3-45. Capacitors installed in an open-rackconfiguration are normally connectedin which of the following manners?

1. Delta2. Parallel3. Series4. Wye

3-46. After a capacitor bank has beeninstalled, it should be inspected andchecked at what minimum interval?

1. Once a week2. Once a month3. Twice a month4. Once a year

3-47. Maintenance for an oil switchoperating a capacitor bank should beperformed after the switch has beenoperated on and off for what maximumnumber of times?

1. 5002. 1,5003. 2,5004. 3,000

3-48. A surge arrester performs which of thefollowing functions?

1. Allows follow-up currents to flowto ground

2. Drains off excess voltage throughthe capacitor banks

3. Drains off excess voltage to ground4. Drains off excess current to ground

3-49. Enclosed cutouts are designed tooperate at what maximum voltage?

1. 2,400volts2. 5,000 volts3. 7,200 volts4. 10,000volts

3-50. Primary fuse links with no electricalload must withstand what minimumpound pull?

1. 52. 103. 154. 25

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3-51. For an electrical distribution system tobe safe, distribution transformers areprotected against the slightest overload.

1. True2. False

3-52. What is the minimum number oflineman required to open a gangedthree-way switch?

1. One2. Two3. Three4. Four

3-53. Opening a disconnect switch in acircuit where current is flowing couldcause which of the followingconditions?

1. Circuit overload2. Circuit overcurrent3. Circuit overvoltage4. Short circuit

3-54. The oil in an oil switch serves which ofthe following purposes?

1. Lubricant for the moving parts2. Extinguishing agent for the

electrical arc3. Coolant during heavy loads4. Insulator for the live parts

3-55. When an oil switch opens a circuitautomatically because of an overloador short circuit, which of the followingcomponents should be installed withthe oil switch?

3-56. What is the purpose of a recloser in adistribution circuit?

1. It opens the circuit in case of afault, locks the switch in the openposition, then recloses the circuitimmediately after the fault iscorrected

2. It recloses an open circuitautomatically after the circuit hasthe sufficient amount of power

3. It recloses an open circuit onlywhen it is signaled remotely by thesubstation operator to close

4. It opens the circuit in case of atemporary fault and recloses thecircuit a few times until the fault iscorrected

3-57. A recloser could be set to re-close atwhat maximum number of times?

1. One2. Five3. Three4. Four

3-58. Which of the following statementsdescribes a difference between a fuselink and a recloser?

1. A fuse link has a lower ampererating

2. A fuse link has a higher voltagerating

3. A fuse link can distinguish betweentemporary and permanent fault

4. A fuse link cannot distinguishbetween temporary and permanentfault

1. Fuse2. Magnetic relay3. Overload relay4. Trip coil

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3-59. When a de-energized line runs parallelto an unloaded energized line, which ofthe following electrical characteristicscould be picked up?

1. Capacitance2. Static current3. Static voltage4. Induced voltage

3-60. When a de-energized line runs parallelto a loaded energized line, which of thefollowing electrical characteristicscould be picked up?

1. Capacitance2. Static current3. Static voltage4. Induced voltage

3-61. When working with de-energizedpower lines, which of the followingprecautions is the best way to avoidaccidentally energizing the lines?

1. Post a watchstander by the powerswitch

2. Put a lock on the power switch3. Install short circuiting and

grounding: leads to the lines4. All of the above

3-62. What is the maximum recommendeddistance between manholes?

1. 400 feet2. 500 feet3. 600 feet4. 1,000 feet

3-63. What is the smallest allowable size of amanhole?

1. 2- by 3-foot2. 3- by 4-foot3. 5- by 7-foot4. 6- by 6-foot

3-64. When determining the size of manholeto be used for transformers, how manycubic feet should you allow perkilovoltampere rating of thetransformer?

1. 1 to 1 l/22. 2 to 33. 3 1/2 to 44. 4 l/2 5to

3-65. Uppermost ducts installed on amanhole should have a minimum ofwhich of the following depths from theground?

1. 18 inches2. 30 inches3. 3 feet4. 4 feet

3-66. Communication cables installedunderground should be buried at whatminimum depth?

1. 18 inches2. 2 feet3. 3 feet4. 30 inches

3-67. Before you completely bury anunderground cable, what should youplace above the cable?

1. Concrete markers2. Plastic streamers3. Three-inch layer of sand4. Each of the above

3-68. A 600-volt direct burial cable shouldbe installed at what minimum depth?

1. 12 inches2. 18 inches3. 24 inches4. 30 inches

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3-69. Which of the following means shouldbe used for water drainage from amanhole?

1. Ducts that slope down from themanhole

2. Pumps installed in the manhole3. A central drain hole, a dram line,

and a sump for the manhole4. A series of drainage holes bored on

the deck of the manhole

3-70. When a duct line is set in concrete,there should be a minimum of howmany inches of concrete around eachline of duct?

1. 62. 93. 34. 12

3-71. Which of the following methods isused to clean ducts?

1. Wiping2. Vacuuming3. Rodding4. Each of the above

3-72. You are pulling multiple cablesthrough a duct. You should pull thecable at what rate?

1. 25 feet per minute2. 35 feet per minute3. 50 feet per minute4. 75 feet per minute

3-73. Before you enter an undergroundstructure, which of the followingpeople must certify it as being safe?

1. Safety chief2. Safety officer3. Confined space manager4. Commanding officer

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ASSIGNMENT 4

TextbookAssignment: “Electrical Distribution,” chapter 4, pages 4-33 through 4-37, “InteriorWiring,” chapter 5, and “Fiber Optics and Lighting,” chapter 6, pages 6-1 through 6-8.

4-1. An ammeter has which of thefollowing electrical characteristics?

1. High internal resistance2. High power consumption3. Low internal resistance4. Low voltage rating

4-2. When an ammeter is connected acrossa voltage source, which of thefollowing conditions will occur?

1. The circuit will be overloaded2. The circuit will consume excessive

power3. The ammeter will be damaged4. The ammeter will read the current in

the reverse direction

4-3. Before breaking a circuit connectionfor an ammeter, what should be yourfirst step?

1. Set the meter at its highest range2. Energize the circuit3. De-energize the circuit4. Set the meter at its lowest range

4-4. When taking measurements on adirect-current circuit you shouldconnect the ammeter to the correctpolarity.

1. True2. False

4-5. Before connecting an ohmmeter into acircuit, what step should you do first?

1. Place the meter to its highest range2. Check the polarity of the meter3. Make sure current is in the circuit4. Make sure there is no voltage in the

circuit

4-6. Before placing the test leads of anohmmeter into the terminals of acapacitor, what step should you dofirst?

1. Ground the case of the capacitor2. Charge the capacitor3. Discharge the capacitor4. Ground the ohmmeter

4-7. You should not use a low-voltagemegger to test high-voltage insulationbreakdown for which of the followingreasons?

1. The megger will be damaged2. The megger will not read accurately3. The insulation will be damaged4. The megger will not indicate any

reading

4-8. To dry a wet digital multimeter, youshould use low-pressure clean air atwhat maximum pounds per square inch(psi)?

1. 102. 203. 254. 30

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4-9. Cross-modulation interference iscaused by which of the followingconditions?

1, Ionized air in the vicinity of powerlines

2. Localized excessive voltage stress3. Corroded connections in distribution

lines4. Cracked power line insulation

4-10.Spark-discharge interference is causedby which of the following conditions?

1. Ionized air in the vicinity of powerlines

2. Corroded connection in distributionlines

3. Cracked power line insulation4. Both 2 and 3 above

4-11. When working on distribution lines,what action should you take to protectyour high-voltage rubber gloves?

1. Wear cotton gloves over them2. Avoid handling sharp objects3. Wear leather gloves over them4. Use them only on de-energized

circuits

4-12.How often should rubber gloves begiven an air test?

1. Yearly2. Monthly3. Weekly4. Each day, before using the glove

4-13.What action should you take to protectrubber gloves from mechanicaldamage?

1. Leave the rubber gloves inside thecotton gloves

2. Leave the rubber gloves inside theleather gloves

3. Store the gloves inside a canvas bag4. Store the gloves in dry storage

4-14.Besides mechanical damage, rubbergloves should be protected from whichof the following conditions?

1. Moisture2. Dryness3. Sunlight4. Chemical exposures

4-15.A rubber insulating insulator hood isused to cover what distribution systemcomponent?

1. Bare conductor2. Suspension insulator3. Strain insulator4. Post insulator

4-16. If a direct burial cable is installedunderneath a four-inch concrete slab, itshould be buried at what minimumdepth?

1. 6 inches2. 18 inches3. 24 inches4. 30 inches

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4-17.If a direct burial cable is installedunderground without covering, itshould be buried at what minimumdepth?

1. 6 inches2. 12 inches3. 18 inches4. 24 inches

4-18.Type UF cable can be used in whatlocation?

4-22. If an interior wiring system is notinstalled underground, where is thestarting point located?

1. At the service entrance2. At the watt-hour meter3. At the panel board4. At the service drop

4-23. Power feeders should never besuspended less than what minimumdistance above a walkway?

1. A service entrance 1. 10 feet2. Embedded in concrete 2. 12 feet3. A wet location 3. 18 feet4. In a storage-battery room 4.20feet

4-19. An electrical wiring system installed inan underfloor raceway should havewhat maximum voltage?

1. 110 V2. 220 V3. 440 V4. 600 V

4-24.Communications circuits should beinstalled in what enclosure?

1. In the same enclosure with lightcircuits

2. In the same enclosure with powercircuits

3. In an enclosure all by itself

4-20.Underfloor raceway ducts should be 4-25.Conductors installed in raceways thatfilled with conductors up to what are No. 8 AWG or larger should bemaximum percentage of its crosss e c t i o n a l a r e a ?

configured in which of the followingways?

1. 90%2. 80%3. 50%4. 40%

1. Solid2. Stranded3. Securely fastened to the raceway4. Groundedto the raceway

4-21.For general installation, underfloorraceways should be installed at leasthow many inch(es) below the surfaceof a floor?

4-26. If an overcurrent device or circuitbreaker is located in a panel board andrated at 80 amperes, it should have aload that does not exceed how manyamperes?

1. 1 inch2. 2 inches3. l/2 inch4. 3/4 inch

1. 602. 643. 804. 100

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4-27.The insulation of an equipment-grounding conductor should have whatouter color?

1. White2. Green with yellow stripes3. Gray4. Gray with yellow stripes

4-28.You have a conductor with blackinsulation that you want to use as anequipment ground conductor. Whatshould you do with the wire beforeinstalling it?

1. Put a yellow stripe on the insulation2. Color the exposed insulation white3. Mark the exposed insulation with

gray tape4. Strip the insulation from the entire

exposed length of the wire

IN ANSWERING QUESTIONS 4-29 AND4-30, REFER TO TABLE 5-2 INCHAPTER 5.

4-29.When a No. 2 AWG copper wire isinstalled vertically in a multistorybuilding, it should be supported atwhat intervals?

1. Every 200 feet2. Every 180 feet3. Every 100 feet4. Every story

4-30. When a No. 6 copper conductor isinstalled vertically in a multistorybuilding and supported by thedeflection method, it should besupported at what intervals?

1. Every 100 feet2. Every 200 feet3. Every 50 feet4. Every 20 feet

4-31.An electrical circuit can be testedsafely and inexpensively using whichof the following test equipment?

1. Digital multimeter2. Line-voltage tester3. Light bulb tester4. Neon tester

4-32.When you use a power bender, whatprocedures should you follow?

1. The same procedures as manualbenders

2. The procedures recommended by theconduit manufacturer

3. The procedures recommended by thebender manufacturer

4. The same procedures as any otherpower bender

IN ANSWERING QUESTION 4-33,REFER TO TABLE 5-3 IN CHAPTER 5.

4-33. When bending with power benders andthe manufacturer’s chart is notavailable, what should be the minimumstub length of a 1 -inch conduit?

1. 1 7/8 inches2. 2 3/8 inches3. 10 inches4. 13 inches

4-34. Before turning the motor of a powerbender to bend a conduit, what safetycheck should you make?

1. Make sure the power is on2. Make sure that the bender is

perfectly leveled to the floor3. Make sure the lock pins are properly

engaged4. Make sure the conduit is g-rounded

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4-35.A conduit run from one outlet to thenext should only have what maximumnumber of bends?

1. Seven2. Six3. Five4. Four

4-36.Wooden plugs should never be used asanchors for which of the followingreasons?

1. They cure in a short time2. They might stain the wall3. They eventually loosen in the hole4. Each of the above

IN ANSWERING QUESTION 4-37,REFER TO TABLE 5-4 IN CHAPTER 5.

4-37. You are installing two l/2 inch conduitruns parallel to each other. What is theproper spacing between the conduits?

1. 1 5/8 inches2. 7/8 inch3. 5/8 inch4. 25/32 inch

IN ANSWERING QUESTION 4-38,REFER TO TABLE 5-5 IN CHAPTER 5.

4-38. A 1 1/2-inch rigid conduit installed in astraight run should be supported atwhat maximum interval?

1. 10 feet2. 12 feet3. 14 feet4. 16 feet

4-39. Which of the following wire splices issimple to make?

1. Western Union2. T-tap3. Portable chord splice4. Pigtail

4-40. Which of the following wire splices isthe most difficult to make?

1. Western Union2. T-tap3. Portable chord splice4. Pig tail

4-41. When soldering wires, you should notleave the unsoldered splice exposed tothe air for a long period of time forwhich of the following reasons?

1. The exposed splice will oxidize2. The exposed wire will collect dirt3. The exposed splice will collect

moisture4. All of the above

4-42. What means should you use to cool asoldered splice?

1. Dip it in water2. Blow on it3. Allow it to cool naturally4. Apply a damp rag to it

4-43. Which of the following tools shouldyou use to remove a fuse from a switchbox?

1. Electrician’s pliers2. Needle nose pliers3. Fuse puller4. Each of the above

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4-44. Which of the following methodsshould you use to replace a fuse?

1. Install the fuse first into the line sideof the fuse clip, then into the loadside

2. Install the fuse into the load side andline side fuse clips at the same time

3. Install the fuse first into the load sideof the fuse clip, then into the lines i d e

4. Each of the above

4-45. Which of the following statements iscorrect about the use of portableelectric tools?

1. Make sure all tools you use have athird plug

2. Make sure all tools are doubleinsulated

3. Make sure all tools are grounded4. Make sure you use GFCI on any tool

IN ANSWERING QUESTIONS 4-46 AND4-47, REFER TO TABLE 5-6 IN CHAPTER5.

4-46. What OSHA safety color code is usedto indicate a cutting device?

1. Purple2. Orange3. Yellow4. Red

4-47. What OSHA safety color code is usedto designate emergency stop switches?

1. Orange2. Yellow3. Red4. Green

4-48. What is the very first thing you shoulddo when you discover a fire in yourwork place?

1. Make a reasonable effort to put outthe fire

2. Call the fire department3. Pull the fire alarm and alert all

workers in the work place4. Contact your immediate supervisor

4-49. A fire in an electric motor is designatedas what type of fire?

1. Class A2. Class B3. Class C4. Class D

4-50. Fire in a paint locker should beextinguished with what which of thefollowing agents?

1. Water2. Carbon dioxide3. Dry chemicals4. Both 2 and 3 above

4-51. The best extinguishing agent forelectrical fires is water.

1. True2. False

4-52. What fiber-optic device convertselectrical signals to optical signals?

1. Transducer2. Converter3. Transmitter4. Inverter

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4-53. What fiber-optic transmittercomponent receives incomingelectrical signals?

1. Receiver2. Source drive circuit3. Coupler4. Interface circuit

4-54.What is the difference between asemiconductor LED and an LD?

1. An LED emits coherent light whilean LD does not

2. An LED has a fixed-phaserelationship while an LD lacks thisrelationship

3. An LED is more economical tooperate than an LD

4. An LED is more expensive tooperate than an LD

4-55. Semiconductor lasers emit light at aspread of what angle?

1. 2 to 4 degrees2. 5 to 7 degrees3. 10 to 15 degrees4. 16 to 20 degrees

4-56.Which of the following is the mostcommon material used to produce asemiconductor?

1. Silicon2. Indium3. Aluminum4. Phosphorus

4-57. Light from a laser is produced throughwhat process?

4-58.Which of the following statements iscorrect concerning electric energy inthe operation of an LED and an LD?

1. All electrical energy is converted tooptical energy

2. A small amount of electrical energyis converted to heat energy

3. A substantial amount of electricalenergy is converted to optical energy

4. A substantial amount of electricalenergy is converted to heat energy

4-59.What component is used to moreefficiently couple light from a lightsource to an optical connector?

1. Optical pigtail2. Coupler3. Lens4. Transducer

4-60. Which of the following fiber-opticcomponents converts the weakenedand distorted optical signal back intoan electrical signal?

1. Transmitter2. Amplifier3. Receiver4. Coupler

4-61. Which of the following is the purposeof an optical detector?

1. To generate an optical pulseproportional to the input current

2. To convert an optical signal into anelectrical signal

3. To convert an electrical signal intoan optical signal

4. To amplify the optical output signal1. Spontaneous emission2. Simulated emission3. Simultaneous emission4. Stimulated emission

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4-62. What type of fiber-optic link consistsof two simple point-to-point linkstransmitting in opposite directions?

1. Simplex2. Composite3. Full duplex4. Opposite

4-63. What instrument is recommended fortaking field measurements on aninstalled optical fiber cable that is 100feet long?

1. Optical loss test reflectometer2. Digital multimeter3. Optical time domain reflectometer4. Optical time domain refractometer

4-64.What fiber-optic cable splice isconsidered a permanent splice?

1. Adhesive splice2. Mechanical splice3. Welded splice

4-65. In a V-groove splice, what material orcomponent completes the assemblyprocess by bonding the ends of thefiber-optic cable?

1. The substrate2. The flat spring3. The transparent adhesive4. The alignment sleeve

4-66.Which of the following techniques isthe most popular technique used forfusion splicing?

4-67.What was the first heating elementused for fusion splicing?

1. Gas flame2. Chrome wire3. Carbon-dioxide laser4. Nichrome wire

1. Carbon-dioxide-laser fusion2. Nichrome-wire fusion3. Electric-arc fusion4. Gas-flame fusion

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ASSIGNMENT 5

Textbook Assignment:“Fiber Optics and Lighting Systems,” chapter 6, pages 6-9 through 6-50;“Electrical Equipment,” chapter 7; “Alarm Systems,” chapter 8.

5-1. In street lighting, streets are classifiedinto how many categories?

1. Five2. Two3. Three4. Four

5-2. Which of the followingmeasurements should NOT be usedas a mounting height for a lightingluminaire?

1. 18 feet2. 20 feet3. 25 feet4. 30 feet

5-3. A luminaire overhang should notexceed what percentage of itsmounting height?

1. 25%2. 30%3. 35%4. 40%

5-4. What technical information does aluminaire utilization curve show?

1. The distribution of illumination onthe road surface in the vicinity ofthe luminaire

2. The amount of light generatedwithin the luminaire

3. The amount of light that falls onthe roadway and adjacent areas

4. The magnitude and direction oflight coming from the luminaire

5-5. What technical information does aluminaire isofootcandle curve show?

1. The distribution of illumination onthe road surface in the vicinity ofthe luminaire

2. The amount of light generatedwithin the luminaire

3. The amount of light that falls onthe roadway and adjacent areas

4. The magnitude and direction of thelight coming from the luminaire

5-6. When performing lightingcalculations, what factor should youinclude to compensate for the gradualloss of illumination that is due toaccumulated dirt on the luminairesurface?

1. Power factor2. Correction factor3. Maintenance factor4. Illumination factor

5-7. Floodlighting luminaries have whattotal number of National ElectricalManufacturer’s Association (NEMA)classifications?

1. Five2. Two3. Three4. Four

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5-8. A general-purpose floodlight, with an 5-1 3. What airfield lighting standards areintegral ballast, has what NEMA followed by U.S. military airfieldsclassification? overseas?

1. GP2. GPB3. HD4. HDB

5-9. A NEMA Type 5 floodlight has ahorizontal and vertical beam spreadof how many degrees?

1. 21 1. Five2. 22 2. Two3. 45 3. Three4. 77 4. Four

5-10. You are performing lightingcalculations and the manufacturer’sinformation is not available for anenclosed floodlight. Whatmaintenance factor should you use inthe calculation to compensate for thegradual loss of illumination?

1. 0.762. 0.703. 0.654. 0.55

5-1 1. What types of airfield is/are bestsuited for helicopter operations?

1. VTOL2. VSTOL3. Both 1 and24. SELF

5-12. What type(s) of airfield canaccommodate the landing of high-performance aircraft?

1. NAVFAC standards2. The host nation’s aviation

standards3. FAA standards4. U.S. Air Force standards

5-14. The SELF has how many sets ofFLOLS and field lighting systems?

5-15. In an airfield lighting control circuit,the hot lead is what size of wire?

1. No. 6 AWG2. No. 7 AWG3. No. 12 AWG4. No. 17 AWG

5-16. In an airfield lighting control circuit,what color is the hot lead?

1. Red2. Blue3. Black4. Orange

5-17. Runway edge lights should beinstalled at what maximum distancefrom the edge of the runway paving?

1. 5 feet2. 2 feet3. 10 feet4. 15 feet

1. VSTOL2. SELF3. EAF4. Both 2 and3

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5-18. When approach lighting circuits areto be installed above ground and theairfield area is not fenced, the circuitshould be installed at what minimumheight?

1. 8 feet2. 10 feet3. 12 feet4. 22 feet

5-19. The power supply for a runwaydistance marker light should be thesame as the power supply forapproach lights.

1. True2. False

5-20. In an obstruction lighting system,what color are the lights?

1. Orange2. Yellow3. Blue4. Red

5-2 1. There are how many types offunctional beacons?

1. Five2. Two3. Three4. Four

5-22. Which of the following beacons usesa flashing light instead of a rotatinglight?

1. Airport beacon2. Identification or code beacon3. Hazard or obstruction beacon4. Both 2 and 3

5-23. When you are working very nearairfield strobe lights during anairfield operation, what safetyprecaution should you follow?

1. Wear sunglasses2. Do not look directly at the light

beam3. Cover the strobe lights to block

their light4. Turn off the power to the strobe

lights

5-24. When, if ever, does the control towerhave any control over the airfieldstrobe lighting?

1. Only when the local/remote controlunit in the sequence timer cabinetis in the local-on position

2. Only when the local/remote controlunit in the sequence timer cabinetis in the remote position

3. Never

5-25. When you are performing anoperational test during routinemaintenance on an airfield lightingsystem, you should leave the light onfor at least how many hours?

1. 12. 23. 64. 4

5-26. What will happen in an airfieldlighting circuit when the outputterminals of a constant-currentregulator (CCR) in the circuit areaccidentally shorted?

1. The circuit will be overloaded2. There will be a short circuit3. The CCR will have a no-load

condition4. The CCR will be damaged

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5-27. What will happen to a CCR in alighting circuit if its secondaryterminals are left open without aload?

1. It will be overloaded2. It will be shorted3. It will have a no-load condition4. There will be no significant effect

to the CCR

5-28. NEW® requirements for motor-branch circuit and ground faultprotection can be found in what partof Article 430?

1. A2. B3. C4. D

5-29. Motor-branch circuit protection mustprotect which of the following circuitcomponents?

1. The motor2. The control apparatus3. The conductors4. All of the above

5-30. Which of the following devices canbe considered a motor controller?

5-31.

1. Pilot control device2. Circuit breaker3. Push button station4. Limit switch

The NEC® considers a motorcontroller to be out of sight when thecontroller is more than how manyfeet from the motor?

1. 102. 153. 254. 50

5-32. An approved disconnecting meansfor a motor circuit should have whatkind of rating?

1. Ampere2. Horsepower3. Kilowatt4. Voltage

5-33. The Code permits a motordisconnecting means to be out ofsight if what condition can be met?

1. It can be locked in the ON position2. It can be locked in the OPEN

position3. It can not be locked in the ON

position4. It can not be locked in the OPEN

position

5-34. A motor overload protection shouldbe capable of protecting the motorfrom which of the following circuitcondition(s)?

1. Short circuit2. Ground fault3. Excessive circuit heat4. All of the above

5-35. What must be done to a regular fuseused as an overload protection for amotor during the motor’s startingperiod?

1. It must be grounded2. It must be shunted3. It should be outfitted with a time-

delaying device4. None of the above

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5-36.

5-37.

5-38

5-39.

When flexible metal conduit used as agrounding conductor exceeds itspermitted length, you should installwhat component in the conduit?

1. A neutral wire2. An additional hot wire3. A bonding jumper wire4. A connector listed for grounding

A flexible metal conduit used as anequipment grounding conductorshould have circuit conductors withinit rated at what maximum amperes?

1. 102. 153. 204. 25

5-40. A control circuit is divided into howmany classes?

1. Five2. Two3. Three4. Four

Which of the following non-currentcarrying metal parts of a motorcircuit is/are required to begrounded?

1. Cabinets2. Boxes3. Equipment enclosures4. All of the above

Flexible metal conduit is permitted tobe used as an equipment groundingconductor provided its length doesnot exceed how many feet?

1. 62. 103. 154. 20

5-41.

5-42.

5-43.

In a class 1 control circuit, a number18 wire should be protected at howmany amperes?

1. 72. 103. 164. 18

In a two wire control circuit, whatcomponent opens and closes thecircuit?

1. Circuit breaker2. Start-stop button3. Toggle switch4. Automatic pilot device

In a three-wire control, what is thefunction of the maintaining circuit?

1. To maintain the voltage of thecircuit

2. To maintain the current of thecircuit

3. To maintain power to the circuit4. To eliminate the need for the

operator to press constantly on thestart button to keep the controllercoil energized

5-44. Which of the following is anotherterm for a maintaining circuit?

1. Control circuit2. Sealing circuit3. Holding circuit4. Both 2 and 3

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5-45. Which of the following componentsis commonly used to open and closethe circuit?

1. Limit switch2. Circuit breaker3. Push button station4. Float switch

5-46. A low-voltage control uses a separatelow voltage source from which of thefollowing components?

1. Adjustable resistor2. Rectifier3. Isolation transformer4. Small generator

5-47. The low-voltage control’s supplyvoltage should come from the samepower supply as the motor it iscontrolling.

1. True2. False

5-48. Lockout guidance is provided bywhat instruction?

1. OPNAVINST 5010.232. OPNAVINST 5001.233. OPNAVINST 5100.324. OPNAVINST 5100.23

5-49. If a motor does not start when themain contacts of the controller close,which of the following conditionsis/are the possible cause(s)?

1. Dirty start button contacts2. Open holding coil3. Open overload heater coil4. Each of the above

5-50. If the controller contacts do not closewhen the start button is pressed,which of the following conditions is apossible cause?

1. Defective load2. Grounded circuit3. Over voltage4. Shorted coil

5-51. If the controller contacts open whenthe start button is pressed, which ofthe following conditions is a possiblecause?

1. A shorted coil2. Wrong connection of the push

button station3. Over voltage4. An open overload relay

5-52. If a magnetic coil is noisy while inoperation, which of the followingconditions is a possible cause?

1. Shorted contacts2. Shorted coil3. Grounded coil4. Broken shaded pole

5-53. Grease used for lubricating motorbearings should have a melting pointnot less than how many degrees?

1. 150°F2. 212°F3. 100°C4. 150°C

5-54. What is the most common lubricationproblem on newer motors?

1. Infrequent greasing2. Overgreasing3. Undergreasing4. Grease melting

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5-55. When using an external heating unitto dry moisture from a Class Ainsulated motor, you should not allowthe motor windings to exceed whattemperature?

1. 150°C2. 100°C3. 150°F4. 100°F

5-56. What condition indicates anoverheated commutator?

1. A polished brown color on thesurface of the commutator

2. A bluish color on the surface of thecommutator

3. An uneven wear on thecommutator

4. A worn out commutator brush

5-57. After you install an electric motor,how long should you initially leavethe motor running with a load forobservation?

1. 1 hour2. l/2 hour3. 5 minutes4. 15 minutes

5-58. Which of the following reasons is/arethe purpose of a building alarmsystem?

1. To protect property2. To detect an intrusion3. To protect life4. All of the above

5-59. What is an annunciator?

5-60. What Article in the NEC® covers theinstallation of wiring and equipmentof fire-protective signaling systems?

1. 6072. 6703. 7064. 760

5-61. In a security wiring circuit, whatcomponent allows an authorizedperson to leave and enter the premiseswithout causing an alarm when thesystem is on?

1. Tamper switch2. Key-operated timer3. Shunt lock4. Tuner switch

5-62. Which of the following types ofinstallation for fire and securitywiring systems is the most difficult toaccomplish in an existing building?

1. Surface mounted conduit2. Wire molding3. Concealed wiring4. Exposed wiring

5-63. Which of the following drills isrecommended for drilling holes usinga flexible shaft?

1. Low-speed2. High-speed3. High torque4. Reversible

1. A public address system2. An audible indicating device3. A visual indicating device4. A coding device

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5-64. In the installation of burglar alarmwiring through a window casement,what size of flexible shaft isrecommended?

1. l/4 inch2. 5/16 inch3. 3/8 inch4. l/2 inch

5-65. While pulling a wire with a flexibleshaft attached to a drill, when, if ever,should you reverse the direction ofthe drill?

1. All the time while pulling the wire2. Only when the wire is hard to pull3. Only when the bit is passing

through a wooden member4. Never

5-66. Security and fire alarm systems’wiring ranges from what AWG sizes?

l. No. 10 to No. 82. No. 14 to No.123. No. 20 to No.164. No. 22 to No.18

5-67. What component is the heart of anysecurity system?

1. Bell2. Horn3. Control panel4. Switchboard

5-68. A good rechargeable power supplyshould be able to operate an alarmsystem for how many hours withoutbeing recharged?

1. 8 hours2. 12 hours3. 24 hours4. 48 hours

5-69. A non-rechargeable standby batterypower supply for fire alarms is stillpermitted for use by the NFPA.

1. True2. False

5-70. Surface magnetic detectors can bemounted by using which of thefollowing materials?

1. Epoxy2. Double-sided tape3. Screws4. All of the above

5-71. When installing a detector onwindows, the two sections of thedetector should be no more than howmany inches apart?

1. 1/4 inch2. 3/8 inch3. l/2 inch4. 5/8 inch

5-72. The conductive foil in an alarmsystem is connected to whatconductor?

1. Neutral2. Ground3. Positive4. Negative

5-73. What type of motion detector is usedto detect sounds caused by anintruder?

1. Infrared detector2. Ultrasonic detector3. Sound wave detector4. Audio detector

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5-74. Which of the following detectors isused to protect large areas such asconstruction sites?

1. Infixed2. Audio3. Microwave4. Vibration

5-75. The proper performance of anultraviolet-radiation fire detectorcould be affected by which of thefollowing factors?

1. Sunlight2. Welding arc3. Lightning4. Both 2 and 3

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Page 286: Construction Electrician Intermediate ELECTRICIAN ADVANCED ... continuation of information covered in the Construction Electrician Intermediate ... vi INSTRUCTIONS FOR ...

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