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conductors from coming in contact with each other or any other conductor. If conductors are allowed to make contact, a short circuit is created. In a short circuit, current passes through the shorting material without passing through a load in the circuit, and the wire becomes overheated. Insulation keeps wires and other conductors from touching, which prevents electrical short circuits. Insulation prevents live wires from touching people and animals, thus protect- ing them from electrical shock.

A 29-year-old male maintenance worker was found at 3:45 a.m. lying on his back and convulsing. Beside him were an overturned cart and an electric welding machine, both lying in a pool of water on the concrete floor. Arcing was visible between the welding machine and the floor. The worker was transported to the closest hospital, where he was pronounced dead.

An examination of the welding machine showed that there were exposed conductors in the machine s cables. There were numerous cuts and scrapes in the cables’ insulation. On other parts of the machine, insulation was damaged or missing. Also, the machine did not have a ground connection.

Investigators concluded that the maintenance worker was electrocuted when he tried to turn off the weld- ing machine, which was sitting on the cart. The metal frame of the machine had become energized due to the damaged insulation. When he touched the energized frame, he completed the conducting path to ground. The current traveled through his body to ground. Since he was probably standing in wate , the risk of a ground fault was even greater.

You must take steps to decrease such hazards in your workplace:

  • Ground circuits and equipment.

  • Keep all equipment in good operating condition with a preventive maintenance program.

  • Never use electrical equipment or work on circuits in wet areas. If you find water or dampness, notify

your supervisor immediately.

Insulation helps protect wires from physical damage and conditions in the environment. Insulation is used on almost all wires, except some ground wires and high-voltage power lines. Insulation is used internally in tools, switches, plugs, and other electrical and electron- ic devices.

Special insulation is used on wires and cables that are used in harsh environments. Wires and cables that are buried in soil must have an outer covering of insulation that is flame-retardant and resistant to moisture, fungus, and corrosion.

In all situations, you must be careful not to damage insulation while installing it. Do not allow staples or other supports to damage the insulation. Bends in a cable must have an inside radius of at least

Make sure insulation is the right type and in good condition.

Section 7

Page 47

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