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615 Electrical Safety - Hazards and Controls
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Protection from Energized Parts

A break in an electric tool's or machine's insulation can cause its metal parts to become "hot" or energized, meaning that they conduct electricity.

Worker using a properly grounded power tool
This shows properly grounded power tools.

Touching these energized parts can result in an electrical shock, burn, or electrocution.

The best way to protect yourself when using electrical tools or machines is to establish a low-resistance path from the device's metallic case to the ground. This requires an equipment grounding conductor, a low-resistance wire that directs unwanted current directly to the ground.

A properly installed grounding conductor has a low resistance to ground and greatly reduces the amount of current that passes through your body. Cord and plug equipment with a three-prong plug is a common example of equipment incorporating this ground conductor. Never use a three-prong plug if the center ground prong is missing.

Another form of protection is to use listed or labeled portable tools and appliances protected by an approved system of double insulation or its equivalent. Where such a system is employed, it must be marked distinctively to indicate that the tool or appliance uses an approved double insulation system.

For more information, check out OSHAcademy course 710 Energy Control Program (Lockout/Tagout).

Knowledge Check Choose the best answer for the question.

3-6. What should you do with a power plug with a missing center ground prong?