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115 Electrical Safety for Employees: Basic
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Protection from Energized Parts

If the insulation of an electric tool or machine is compromised, its metal parts can become 'hot' or energized, which means they start conducting electricity.

Make sure to properly ground power tools.

Contact with these energized parts can lead to an electrical shock, cause burns, or even result in 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. Equipment with a cord and a three-prong plug is a common example of equipment incorporating this ground conductor. It is important to never use a three-prong plug if the central 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. Tools and appliances employing this system should be distinctly marked to indicate the presence of an approved double insulation system.

Knowledge Check Choose the best answer for the question.

2-6. What should be done if you see a power tool's plug with a missing center ground prong?