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Extension cords may have damaged insulation. Sometimes the insu- lation inside an electrical tool or appliance is damaged. When insula- tion is damaged, exposed metal parts may become energized if a live wire inside touches them. Electric hand tools that are old, damaged, or misused may have damaged insulation inside. If you touch damaged power tools or other equipment, you will receive a shock. You are more likely to receive a shock if the tool is not grounded or double- insulated. (Double-insulated tools have two insulation barri- ers and no exposed metal parts.) You need to recognize that defective insulation is a hazard.

A damaged live power tool that is not grounded or double-insulated is very dangerous! If you touch a damaged live power tool, you will be shocked!

This extension cord is damaged and should not be used.

Improper grounding hazards

When an electrical system is not grounded properly, a hazard exists. The most common OSHA electrical violation is improper grounding of equipment and circuitry. The metal parts of an electrical wiring system that we touch (switch plates, ceiling light fixtures, conduit, etc.) should be grounded and at 0 volts. If the system is not grounded properly, these parts may become energized. Metal parts of motors, appliances, or electronics that are plugged into improperly grounded circuits may be energized. When a circuit is not grounded properly, a hazard exists because unwanted voltage cannot be safely eliminated. If there is no safe path to ground for fault currents, exposed metal parts in damaged appliances can become energized.

fault current—any current that is not in its intended path

Extension cords may not provide a continuous path to ground if there is a broken ground wire or plug. If you contact a defective electrical

ground potential—the voltage a grounded part should have; 0 volts relative to ground

Section 5

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