Case Study
A maintenance man rode 12 feet above the floor on a motorized lift to work on a 277-volt light fixture. He did not turn off the power supply to the lights. He removed the line fuse from the black wire, which he thought was the "hot" wire. But, because of a mistake in installation, it turned out that the white wire was the "hot" wire, not the black one. The black wire was neutral. He began to strip the white wire using a wire stripper in his right hand.
Electricity passed from the "hot" white wire to the stripper, then into his hand and through his body, and then to the ground through his left index finger.
A co-worker heard a noise and saw the victim lying face up on the lift. She immediately summoned another worker who lowered the platform. CPR was performed, but the maintenance man could not be saved. He was pronounced dead at the scene.
You can prevent injuries and deaths by remembering the following points:
- If you work on an electrical circuit, test to make sure that the circuit is de-energized (shut off)!
- Never attempt to handle and wires or conductors until you are absolutely positive that their electrical supply has been shut off.
- Be sure to lock out and tag out circuits so they cannot be re-energized.
- Always assume a conductor is dangerous.
Knowledge Check Choose the best answer for the question.
4-6. Which of the following is a safe work practice when working with electricity?
You forgot to answer the question!