Electric Power

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CPWR - The Center for Construction Research and Training

Summary Statement

This toolbox talk was created by NIOSH and CPWR and covers electrical power hazards. The design allows workers to view a graphic while the facilitator presents the information. After the talk, the sheet can be posted on the jobsite with the graphic side out to reinforce the key points.
2013

CPWR Toolbox Talk logoA mistake around electricity could easily be your last. Even experienced electricians and electrical power installers must be on guard all the time. Non-electricians are at greatest risk of electrocution from contacting overhead lines with aluminum ladders and metal tools.

Here is an Example

Vincent and two co-workers were installing individual electrical units for an apartment building under construction. The circuit breaker protecting the main internal buss for the entire apartment building had been labeled but not locked out. The crew began wiping down the individual units before a pre-startup inspection by the building department. They did not know that the utility workers had energized the internal buss. Vincent began to wipe down one of the units. He contacted the A-phase buss terminal with his right hand and the C-phase buss terminal with his left hand. A path between phases was created and Vincent was electrocuted.

  1. How could this incident have been avoided?
  2. What should you assume about any electrical circuit?

Handling Electrical Power

  • Remember to call your power company and provide information about the electric equipment.
  • Check the voltmeter frequently. If voltage falls below 200 volts for 240-volt service or below 100 volts for 120-volt service, reduce the load on the generator by turning off some electrical equipment.
  • Keep the unit clean and in good running order at all times so it will be ready for immediate use. Dust and dirt accumulations on the motor can cause it to overheat when operated.
  • Lockout all live electric before working on it.
  • Wear arc flash clothing when the electrical source of power cannot be de-energized.
  • Always verify electrical is de-energized by testing with an AC Voltage detector.

What Are We Going to Do Today?

What actions will we take today to prevent arc flashes?

1.____________________________________________________________

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2.____________________________________________________________

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OSHA REGULATION: 1926.416-417

Graphic of a worker holding a voltage detector and talking on the phone while  standing next to a locked-out electrical box.

  • Remember to call your power company and provide information about the electric equipment.
  • Lockout all live electric before working on it.
  • Always verify electrical is de-energized by testing with an AC Voltage detector.