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IS : 3837 - 1976( Reaffirmed 1996 )

Indian StandardSPECIFICATION FORACCESSORIES FOR RIGID STEEL CONDUITS

FOR ELECTR1CA.L WIRING( First Revision )

Fifth Reprint FEBRUARY 1997

UDC 621.315.674

0 Copyright 1976BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

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IS: 3837 - 1976

Indian StandardSPECIFICATION FOR

ACCESSORIES FOR RIGID STEEL CONDUITSFOR ELECTRICAL WIRING

( First Revision jElectrical Wiring Accessories Sectiona 1 Committee, ETDC 44

ChairmanSHRI K. PI. R.~AIASWAXY

Members

Rcprrsenf ingDire;ctz;ehyl of Technical Development,

SEERI . N. BAXWET ( Altematr toShri I;. N. Ramaswamy )DR B. R. C. r4LrAND Caiico Chemicals Plastics and Fibres Division,BombayStfm S. ~IITRA ( A!frmule )SHIiI F. . &PAT Buildings and Communications Department, Govcm-ment of ,Maharashtra, BombaySHRI B. L. DESHP.~SDE ( Altcmde jCUIEP kkECTKIC.

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X6:3637-1976( Contimud/rorn page 1 )

MembersSRXI M. L. KSL~NNAS~EI S. K. Knos~a Ram Kay Engineering Co -Pvt Ltd, KapurthabKhosla Plastics Pvt Ltd. PuneSRBI M. M. Kaor. ( Al&mate )SHRI S. V. MARF~TUSnnr S. N. BANDYOPADHYAY Tariff Advisory CMlm;ttw, Bombay( Alter&e )SRRI B. C. MOHAIVIY Electrical Contractors Association of Maharashtra,BombaySmuR. M. H. CRAWLA ( Alternate )Smtr E. N. Naut~~nlraewm Director of Industries & Commerce, MadrasSoar B. M. SAU Bombay Electric Supply 8s Transport Undertaking,

Snnx V. T. WAMXO ( Altcmat~ ) BombaySam S. K. Snakut Engineer-in-Chiefs Bmnch, Army HeadquartersSHRI K. S. HAXS ( Altmutr ) ( Ministry of Dcfeagt ), New DelhiSBRI K. K. Snll~xr National Test House, CalcuttaSIX-ZRIENTEXDIXGENGINEEBSHRI A. L. GIJPTA ( Alternote ) Central Public Works Department, New DelhiSBRI S. SRIXIVASAN,Director ( Elcc tech ) Director General, ISJ ( Er-&cio M&r )

Panel for Steel Conduits and Their Accessories, ETDC 44 : P2CO?WCflW

@RI T. P. BnsuMcmbns

Central Public Works Departmgnt, New D&i

SecretqySmn A. K. Gocra

:\ssistant Director ( Biec tech ), ISI

SRRI A. L. GTPTA ( Alternate toShri T. P. Basu )*j SRBI R. N. DA-A Shri R. N. Datta & Co, CalcuttaSHRI M. M. Do- ( Al&mate )Smu SATISH C. KAPUB Northern India Conduit Manufacturers Association,New Delhi- .-HRI M. B. Gong ( Altern& )Smu B. C. MOE- Blcctrical Contractors* Associatii of Maharashtra,

Snnr R. M. H. CH~WLA ( Alternate)) BombaySHRI SUBIR K. SEN Conduit Pipe Manufacturcn* Association, CalcuttaSERI 0. P. %iIIWLA Indian Conduit Indudries, Panipat

2

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IS:3837 - 1976Indian Standard

SPECIFICATION FORACCESSORIES FOR RIGID STEEL CONDUITS

FOR ELECTRICAL WIRING( First Revisiqn )0. FOREWORD

0.1 This Indian Standard ( First Revision > was adopted by the IndianStandards Institution on 23 February 1976, after the draft finalized bythe Electrical Wiring Accessories Sectional Committee had been approvedby the Electrotechnical Division Council.0.2 This standard applies to accessories , mainly used to fix the conduitand the fittings in position, and that standard shall be read in co.njunctionwith IS : 1653-1972* and IS : 2667-1964f.0.3 The specification for accessories for rigid steel conduit was firstpublished in 1966. The important features of this revision are asfollows:

a) To ensure international compatibility, the nominal diameters( except 63 mm ) for accessories have been rationalized in linewith the international practice;

b) New sampling plan has been added; andc) Only mild steel has been retained for the material of theaccessories except for bushes.

0.4 While preparing this standard, assistance has been derived fromBS 4568 : Part II : 1970 Steel conduits and fittings with metric threadsof IS0 forms for electrical installations, Part II Fittings and components issued by the British Standards Institution.0.5 For the purpose of deciding whether a particular requirement of thisstandard is complied with, the final value, observed or calculated,expressing the result of a test, shall be rounded off in accordance witbIS : 2-1960:. The number of significant places retained in the roundedoff value should be the same as that of the specified value in thisstandard.

*Specification for rigid steel conduits for electrical wiring ( kcond rcui.rion ).+Specification For fittings for rigid steel conduits for electrical wiring. (Since revised).ZRulcs for rounding off numerical values ( revised .3

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IS:3897-19761.. SCOPE1.1 This standard spec i&s the material, dimensions and other require-ments of accessories ( other than fittings: see IS : X67-1964* ) used withrigid steel conduits for electrical wiring purposes conforming toIS : 1653-19727.2. TERMINOLOGY2.0 For the purpose of this standard, the following definitions in additiorito those specified in IS : 1653-1972t shall apply.2.1 Accca~oriea -Parts other than fittings ( SPCIS : 2667-1964* ) usedin fixing steel conduits.

KOTE - Clips, saddles, pipe hooks, spacing plates, bush and lock nuts supportingand fixing the conduits are typical examples of accessories.2.1.1 Spacing Plate - An accessory used to prevent the conduit frommaking intimate contact with damp plaster, cement walls and ceilingsor gas and water pipes and to keep the conduit straight where it leavesthe fitting.NOTE These spacing plates are used to prevent the conduit from making inti-mate contact with damp plaster, cement wa!ls and ceilings or gas and water piprs.2.1.2 Entry Bush - An accessory used to prevent abrasion where theconduit ends and where the conductors pass through.2.1.3 Lock Nut - An accessory used along with coupler for connectingtwo lengths of conduit, neither of v/hi& may he turned.2.1.4 Plug - An accessory used for closing unused threaded outlets offittings.

3. CONSTRUCTION3.0 General - The details of screw threads for screwed accessories shallbe as specified in 4.2 of IS : 1653-1972t or 6 of IS : 2667-1964* asapplicable.3.1 The saddle shall be ribbed for reinforcement at the crown and shallbe of such a structure as to be attached firmly on the surface of buildingstructure ( wooden ) with two wood screws,. one on each side.3.2 Sppciog Plates - The plates used for spacing the saddle or clipsfrom wall shall be of such a thickness as to keep the conduit straightwhere it leaves the fittings. For example, this shall be equal to dimen-sions C minus half the nominal size of the conduit for the boxes (seeFig. 7 of 1S : 2667-1964* ).

Specification for fittings for rigid steel conduits for rlectrical wirir.g. (Sicc~ r&+ed 1.tSpecihcatioti for rigid steel conduita for electrical wiring ( sccoad revision ).

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Is:3937019763.3 Plug - The ,plug may be recessed to the thickness of the head, thethickness of the wall being not less than 3 mm.

33.1 The details of the screw threads shall be as specified inIS : 1653-1972*. The plug shall be externally threaded.3.4 Lock Nuts

3.4.1 l -hxagonal Lock Nuts - I n the case of hexagonal lock nuts thewidth across flats (see IS : 2027-19677 ) shall be in accordance withTable 6.

3.4.2 Rmmd Lock N uls - In the case of round lock nuts the edge shallbe miHed or castellated. The outer dia of this shall have straight roughknurling on it.3.4.2.1 The dimensions of circular lock nuts may be given by theformula, namely, size of the conduit plus 6 mm, shall be the outer dla ofthe nut and the thickness same as for hexagonal nut.

3.5 Entry Bush - The inside edges of entry bushes shall be smoothlyrounded in order to prevent abrasion of cables. Entries for the bushesshall be formed so as to prevent [he conduit being screwed or pushedright through to the interior of the bush.3.5.1 Round bushes shall have rough straight knurling on diameter.3.53 The bushing shall have the ends of the threads processed byreaming.:,

4. PROTECTION AGAINST CORROSION4.t Accessories shall be adequately protected against rust and corrosionboth eutside and inside, excluding machinessurfaces and screw threads.Each accessory shall be supp!ied with medium or heavy protectivecoating which shall be smooth,. continuous, tough and firmly adherent&nd free from rough and bare places and cracks.

4.1.X Examples of medium protection are:a) stove enamelting,b) air drying paint, andc) +ctrolytic deposits.

4.1.2 Examples of heavy protection are:a) hot-dip galvanized coating, andb) sherardizing.

Specification for rigid stwl cond:lits for electrical wiring ( second revision ).tSpecification for width across flats for spanners ( jrsf revision ).5

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X3:3337-3976(;2 The enamel, if the fittings are enamelled shall be smooth, countinu-ous, tough and firmly adherent, free from rough and missed places andcracks. The screw threads shall be free from enamel and shall have arust protective coating.4.3 The galvanized coating, if the fittings are galvanized, shall adherefirmly to the surfaces of the fittings and shall be smooth and uniformthroughout.4.4 Sherardized fittings, unless otherwise specified, shall have the threadsalso protected by the sherardizing process.5. DIMENSIONS5.1 The dimensions of the accessories shall comply with the appropriatetables as specified below:

Ordinary clipsSingle saddlesMultiple saddlesPipe hooks and crampetsPlugsLock nutsExternally screwed hexa-gonal bushesInternally screwed circularbushes

Table 1Table 2Table 3Table 4Table 5Table 6Table 7Table 8

6. TOLERANCE6.1 All dimensions except those for which tolerances are specificallystated herein or which are definitely stated as being maximum orminimum are to be recorded as nominal dimensions and subject to atolerance of f 5 percent.7. MARKING7.1 Each conduit accessory shall be clearly marked with the following:

a) Manufacturers name or trade-mark, if any; andb) Country of manufacture.

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ISt3837-1976

TABLE 1 DXMENSIONS FOR ORDINARY CLIP!i( chsc 5.1 )

AIJ dimcnsibru in millimetres._~fatcriaJ Mild steel

FLUTED

Sl2.E OFCONDVIT

(1)16202532405063

A B D E F c( &fin ) ( Min ) ( Min ) ( Min 10) (3) (4) (5) (6) (7)35 16 @71 4 15 1846 20 0.9 4 20 2045 25 o-9 5 20 2255 32 1.25 5 25 2665 40 1.25 5 25 3075 50 1.25 5 25 3590 63 1.25 5 25 42

NOTE - The number of flutes is optional.

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SIZEor ACONDTJIT ( Min )

0) (2)16 5020 6025 6532 8040 8550 9563 110

TAB35 2 DIMENSIONS F,OR SINGLE SADDLES( amIsc 5.1 )

All dimensions in miIlimetrcs.Matnial - Mild steel

( A&(3)16202532405063

(4)o-71o-9o-91.25l-251.25i-25

NOTE - The number of flutes is optional.

E F( Mi n )(5) (6)4 154 205 205 255 255 255 25

c( Min )(7)364045526079a3

8

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IS:3637-1976

TABLE 3 DIMENSIONS FOR MULTKPLB SAD?LES( c101lsc .1 )

All dimensions in millimetres.Muterid - Mild steel

k?E o+COh-LWIT

(1)16202532405063

A* B c D( M i n ) ( Min ) ( M in ) ( Mill )

(2) (3) (4)16 1620 1925 . 1932 2240 2250 2263 22

(5) (s)0.71 4O-9 4O-9 41-25 51.25 5l-25 5l-25 5

E Fi c( Min )

(7) (8)15 1020 1020 1025 1025 1025 1025 10

*Size of conduit x No. of conduits plus 1 mm.*Width of saddle.

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IS t 3857 1976TABLE 4 DIMENSIOHS FOR PIyE HOOKS AND CRAMPETS

( c1au.w 5.1 )All dimensions in millimetrcs.Material - Mild steel forgings

SIZE OFCoNDCfT A B c D E F( Min ) ( Min j ( Min ) ( M i n ) ( 1%1 ) ( & a )(1) (2) !3) (4) (5) (6) (7) (8) (9)16 16 II 45 6.5 3.0 65 3.0 l-520 20 16 55 6.5 3.0 6.5 3-o 1.525 25 19 .6O 6.5 4.0 8.0 50 2.532 32 23 70 5.5 4.0 8-O 50 2.540 40 23 80 6.5 5.0 95 5.0 2.550 50 28 90 6-5 5-o 9.5 5.0 2.563 63 35 100 6-5 5.0 9.5 6.5 3.0

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ISr3637-1976

SIZE OF ACOXDUIT ( Afox )

(1) (2)16 1720 2225 2732 3640 4150 50,63 63

TABLE 5 DIMENSIONS FOR PLUGS( clause 5.1 )

All dimensions in millimetres.

B( Mill )(3)8.08.095

11.011-o12.514.0

c D( niin ) ( Nminaf )(4) (5)3.2 163.2 203.2 254.0 325.6 406-4 506.0 63

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Is:3037-1976TABLE 6 DIMENSIONS FOR LOCK NUTS

( Clause 5.1 )

All dimensions in millimetres.

Maferial - Mild steel

_-

. fi__-u- 0c)-l-i

?ilZp: OF THICKNESS WlDTW AcnovsCONDVIT A FLAT(Min)

( k )(1) (2) (3)16 4.8 2220 6.4 2725 6.4 3632 6.4 4140 7.9 50Xl 9.5 6563 95 80

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TAGLE 7 DIMENSIONS FOR EXTERNALLY G-WEDHEXAGONAL RUSHES(ClauCk5.1 1

All dimensions in millimet~.Mater ia l - Moulded insulating

(1)1620253240so

WIDTH THICKNESEACROSSFLATB HZXMB c(2) (3)17 4.822 4.830 4-836 5.641 5-655 6.4

LENGTH BornOVEBALL ED(Min)

(4) (5)19 10-O20 13.524 19-O26 26.228 31-o32 44-4

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X6:3697- 1976

TABLE 8 DKMENSION3 FOR INTERNALLY SCREWEDCXRtXJhAR BUSHES

( Churl? 5.1 )

Ail dimensions in millimetra.

Materi al - Moulded insulatjnq

SIZE OF EXTERNAL LENQTHOF BORE DEPTIiBUSH DIAXETER THREAD D OVERALLA B C E(1) (2 ) (3) (4) (5)16 20 4.8 11.1 7.920 24 4.8 14.3 7.925 29 5.6 19.0 8.?32 36 5.6 26.2 8.740 44 7.9 31.8 11.150 56 8.7 44.4 11.5

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7.2 BIS Certification MarkingThe product may also be nlarked with Standard Mark.

7.2.1 The use of the Standard Mark is goverued by the provisions ofBureau of Indian Standards Act, 1986 aud the Rules and Regulations madethereunder. The details of conditions under which the liceace for the use ofStandard Mark may be granted to manufacturers or producers may be obtainedfrom the Bureau of Indian Standards.

a. TESTS8.0 General -The tests shall be made at the prevailing ambienttemperature unless specified otherwise in the relevant clauses.8.1 Samples and Criteria for Approval -The number of samplesto be selected for tests specified in 8.2 to 8.4 and criteria for approvalshall be in accordance with Appendix A.8.2 Visual Examination - Each conduit accessory shall be examinedvisually for conformity with the requirements specified in 3.8.3 Dimensional Check -Samples selected shall be iested for conect-ness of specified dimensions such as diameter and thickness. In addition,the accessories shall be tested for accuracy of screw threads by mans ofsuitable gauges.8.4 Test for Protective Coating - Samples selected shall be tested forprotective coatings in accordance with 9.5.1 and 9.5.2 of IS : 1653-1972*.If the area available for this is less than 1 cm9 this test shall be car&lout on whatever maximum area is available.

APPENDIX A( lause 8.1 )SAMPLING OF ACCESSORIES FOR RIGID STEELCONDUITS FOR ELECTRICAL WIRING

A-l. LOTA-l.1 In any consignment, all the conduit accessories of the satpe typeand size manufactured by the same factory and during the same period

*Specification for rigid rtccl conduits for electrical wiring ( ssmnd r&ion ).

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IS: 3837.1976shall be grouped together to constitute a lot. Each lot shall, however,consist of maximum of 1000 of conduit fittings.A-l.2 From each lot a certain number of conduits accessories as specifiedin Table 9 shall be selected at random and subjected to acceptance tests.For this purpose IS : 49051968* shall be used.

TABLE 9 SAMPLING SCHEME

(1 (2)upto loo 3101 ,, 300 830i ,, 500 13501 ,, 1000 20

SECOXD ( Nl+ K ) c, GSTAGEx(3; (4) (5) (6)

3 6 0 28 16 0 2

13 26 0 420 40 1 5

A-2. NUMBER OF TESTS AND CRITERIA FOR CONFORMITYA-2.1 In Table 9 .hrr is the size of the first stage sample. Thesesamples shall be selected at random. A sample shall be declareddefective if rt fails in one or more of the acceptance tests. I f the numberofdefectives found in this sample is less than or equal to Cr, the lot shallbe considered as conforming to this standard and accepted. I f thenumber of defectives is greater than or equal to CZ, the lot shall berejected. I f the number of defectives is between Cr and CZ, furthersample of J v2 size shall be selected at random and subjected to acceptancetests.

A-2.1.1 I f the number of defectives in the two samples combined isless than Ca, the lot shall be accepted, otherwise rejected.

*Methods for random sampling.

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AMENDMENT NO. 1 SEPTEMBER 2000TOIS 3837:1976 SPECIFICATION FORACCESSORIES FOR RIGID STEEL CONDUITS FORELECTRICAL WIRING(Fust Reviswn )

(Page 4, cZause3.1 ) Substitute the following for the existing matterThe saddle shsll be ribbed for reinforcement at the crown and shall be of such astructure as to be attached firmly on the surface of building structure/spacingplates with two wooden screws one on each side.

(Page 4, clause 3.2) Insert a new clause afier 3.2;3.2.1 The dimensions of the spacing plate shall be as follows:Length minimum shall be A as per Table 2 for single saddle and shall beA+2C as per Table 3 for multiple saddles.Width minimum shall be F+6 as per Table 2 or Table 3 as the caae may be.Holes for fining of spacing plates shall be provided at the centre of the spacingplates.The holes shall be of minimum 5 mm dia for conduits of dia up to 20 mm andshall be of minimum 6 mm dia for conduits of higher diameter.

~ (Page 8, Table 2) Substitute D for D (Min) (Max)

( Pages 7,8 and 9, Tables 1,2 and 3, Dimension D, Rows 1,2 and 3 ) Substitute the following for existing entries:D

(Min)0.601.01.0

1

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Amend No. 1to IS 3837:1976(Page 10, Table 4) Sustitute the following for the existing figure

t

A

-c R-(Page 11, Table 5, CO12) Substitute the following-for the existing

A.(Max)22263138465669

(Page 13, Tab& 7) Insert the following note at the end of the table:NO113 Extemafly screwed hexagonal bushes are meant for use of terniinstiorM ofconduits in switch boxes.

(Page 14, Table 8) Insert the following note at the end of the table:NOTE Intemstly screwed arcufsr bushes are meant for use of termination of conduitsinjunction boxes.

[ETD14)