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Electricity

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Related Work Activities

• Using power tools

• Digging, excavating and boring

• Exposure to overhead power lines

• Falling branches

• Utility line tree trimming services

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Hazardous Conditions & Unsafe Acts

• Wet skin or damp ground

• Defective tools, cords, and electrical installations

• Working near overhead lines

• Digging near underground utilities

• Taking electrical related risks

• Not respecting the ability of electricity to kill

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Unsafe Work Practices can be Deadly!

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Potential Outcomes

• What happens to you depends on how much, how long, and what part of your body the electricity goes through.

• People have survived shocks of several thousand volts.

• Others have been killed by voltages as low as 12 volts.

• Prevention means not becoming part of the electrical flow.

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Non-Fatal Shocks can Result in Severe Burns

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OSHA Fatal Fact No. 57• He received an electric shock

that killed him.• Worker was climbing a metal

ladder to hand an electric drill to a worker above him.

• The extension cord had a missing grounding prong and that a conductor on the green grounding wire was making intermittent contact with the energizing black wire thereby energizing the entire length of the grounding wire and the drill's frame.

• The drill was not double insulated.

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Electrical Shock

• Helping An Electrical Shock Victim– Call for immediate help.– Disconnect or de-energize the circuit.– Do not try to remove the victim from the

current source!– Touching the victim could cause you to be

shocked as well.

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Path of Least Resistance

• Grounding Electricity – If your body becomes part of the path,

electricity will flow through it.– If that path is through vital organs like your

heart and lungs you can die.– Grounding Electricity means creating an

easy path for current that doesn’t include your body. Electricity always follows through the path of least resistance.

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For Your Safety

• Grounding Electricity– Electrical power tools should have a true

ground or be double insulated.– Never cut off the third ground prong or use

equipment with one of the three prongs broken.

– If you feel a tingling sensation while you are using a tool, stop using the tool immediately. Take it out of service!

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Danger! Missing Ground Prong

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No Third Prong Here Either, Due to an Unauthorized Repair. Do Not Use!

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For Your Safety-Continued• Grounding Electricity

– Inspect wires and plugs on power tools before each use.

– Replace damaged wires or plugs before using equipment. Do not splice wires or tape gashes.

– Extension cords should be rated for outdoor commercial use.

– Never leave a plug in a puddle or other collection of water.

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Danger! This Cord is Beyond Repair!

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Circuit Breakers

• Protecting Equipment– Circuit breakers protect the wiring system

from overloads.– If you become part of the circuit you may trip

the breaker but it may be after a fatal amount of current flows through your body.

– Circuit breakers do not protect people!

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Ground-Fault Circuit Interrupters (GFCI)

• Protecting People– Are designed to keep workers from being

electrocuted. – If there is a short, the GFCI will quickly shut

down the circuit.– A GFCI can be hard wired into an electrical

box.– A portable GFCI can be plugged into any

electrical outlet to protect you.

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GFCIs– Portable GFCIs are common in landscaping– All extension cords must have a GFCI

connected to them, including those running off of a generator.

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Additional Information

• http://www.osha.gov/OshDoc/data_Hurricane_Facts/elect_safety.pdf

• OSH Answers: Electrical Safety - Basic Information

• OSH Answers: Electric Tools - Basic Safety

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Call Before You Dig

• Failure to contact and locate utilities can lead to catastrophic events and large repair bills.

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Planning-Prior to Digging

• CALL BEFORE YOU DIG– Use your local one call system.– All underground utilities should be located.– Once located, utilities must be protected

from damage.

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Overhead Electrical Hazards

• Long, tall, or large equipment can come in contact with overhead power lines:

• Ladders• Long-handled trim saws• Augers• Heavy equipment• Long poles or pipes

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Power Line Clearance

VoltagesVoltages

<< 50 kV 50 kV

200 kV200 kV

350 kV350 kV

500 kV500 kV

650 kV650 kV

800 kV800 kV

Distance fromDistance from

Power LinesPower Lines

10 feet10 feet

15 feet15 feet

20 feet20 feet

25 feet25 feet

30 feet30 feet

35 feet35 feet

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Voltage range (volts) (phase to phase)

Minimum working distance

2,100-15,000 2 ft, 0 in.

15,100-35,000 2 ft, 4 in.

35,100-46,000 2 ft, 6 in.

46,100-72,500 3 ft, 0 in.

72,600-121,000 3 ft, 4 in.

138,000-145,000 3 ft, 6 in.

161,000-169,000 3 ft, 8 in.

230,000-242,000 5 ft, 0 in.

345,000-362,000 7 ft, 0 in.

500,000-552,000 11 ft, 0 in.

700,000-765,000 15 ft, 0 in.

Minimum Working Distances from Energized Conductors for Line-Clearance Tree-Trimmers

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OSHA Fatal Fact

• Workers were constructing a chain link fence in front of a house and directly below a 7200-volt energized power line.

• They were installing 21-foot sections of metal top rail on the fence.

• One employee picked up a 21-foot section of top rail and held it up vertically.

• The top rail contacted the 7200-volt line, and the employee was electrocuted.

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NIOSH Fatal Fact

A landscaping crew felled a 65-foot oak tree, one of the branches caught onto the 69,000 volt power line.

A landscaper was electrocuted and two workers seriously Injured

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Additional Information

• http://www.osha.gov/OshDoc/data_General_Facts/downed_electrical_wires.pdf

• http://www.osha.gov/OshDoc/data_Hurricane_Facts/electrical_safety.pdf

• OSHA Construction eTool: Electrical Incidents

• Face report - http://www.cdc.gov/niosh/face/stateface/ca/93ca006.html

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Material Handling and Storage

Avoid Storing Materials Under Power Lines

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For Your Safety

• A knowledgeable person should assess each work site for safety hazards and design a work plan that addresses those hazards.

• The employer should conduct a job briefing, based on the work plan, before starting work.

• The employer should establish a written safety and health policy.

• Safe tree removal techniques should be used.• Employers should notify the utility company when

work is planned in an area near overhead power lines.

• Employers and employees should become familiar with available resources on safety standards and safe work practices.

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Remember These Important Points

• Assume overhead power lines have no protective insulation and contact may be fatal.

• Work as a team-One worker on the ground spots for the worker on raised equipment.

• Electricity always seeks one or more paths of least resistance.

• Never touch fallen overhead wires. • Notify the power company right away.

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Remember These Important Points

• Check for overhead power lines before doing any work.

• Plan your route of travel to avoid power lines.

• Make sure equipment does not contact power lines.

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Most Important !

You, your equipment, and the materials you work with must

stay at least 10 feet from power lines !

Note: Qualified line clearance tree-trimmers may follow rules which allow closer proximities.