X hits on this document





12 / 92

E L E C T r I C I T Y I S DA N G E r O U S

You can even receive a shock when you are not in contact with an electrical ground. Contact with both live wires of a 240-volt cable will deliver a shock. (This type of shock can occur because one live wire may be at +120 volts while the other is at -120 volts during an alternating current cycle—a difference of 240 volts.). You can also receive a shock from electrical components that are not grounded properly. Even contact with another person who is receiving an elec- trical shock may cause you to be shocked.

A 30-year-old male electrical technician was helping a company service representative test the voltage-regulating unit on a new rolling mill. While the electrical technician went to get the equip- ment service manual, the service representative opened the panel cover of the voltage regulator s control cabinet in preparation to trace the low-voltage wiring in question (the wiring was not color-coded). The service representative climbed onto a nearby cabinet in order to view the wires. The technician returned and began working inside the control cabinet, near exposed, energized electrical conductors. The technician tugged at the low-voltage wires while the service representative tried to identify them from above. Suddenl , the representative heard the victim making a gurgling sound and looked down to see the victim shaking as though he were being shocked. Cardiopulmonary resuscitation (CPR) was admin- istered to the victim about 10 minutes later. He was pronounced dead almost 2 hours later as a result of his contact with an energized electrical conductor.

  • o

    prevent an incident like this, employers should take the following steps:

    • Establish proper rules and procedures on how to access electrical control cabinets without getting


  • Make sure all employees know the importance of de-energizing (shutting off) electrical systems before

performing repairs.

  • Equip voltage-regulating equipment with color-coded wiring.

  • rain workers in CPR.

A maintenance man rode 12 feet above the floor on a motorized lift to work on a 277-volt light fix- ture. 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 strippe , then into his hand and through his bod , and then to 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 worke , 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 any 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.

Page 4

Section 1

Document info
Document views143
Page views144
Page last viewedTue Oct 25 05:28:02 UTC 2016