Protective Measures
Protect Against Electrical Hazards
Most electrical accidents result from one of the following three factors:
- unsafe equipment or installation
- unsafe environment
- unsafe work practices
Some ways to prevent these accidents are through the use of insulation, guarding, grounding, electrical protective devices, and safe work practices.
Insulation
Insulators, such as glass, mica, rubber, or plastic, are used to coat metals and other conductors. They help stop or reduce the flow of electrical current, thus preventing shocks, fires, and short circuits. For the insulation to be effective, it must be appropriate for the voltage level and environmental conditions. Factors like temperature, moisture, oil, gasoline, corrosive fumes, and other potentially damaging substances need to be considered, as they could cause the insulation to fail.
Types of Insulation
Insulation on conductors is often color coded. Equipment insulated for grounding purposes is typically solid green or green with yellow stripes. Grounded conductors are usually covered with white or gray insulation. Ungrounded conductors, also known as 'hot wires,' are often black or red, but they can be any color other than green, white, or gray.
Before connecting electrical equipment to a power source, it is a good idea to check the insulation for any exposed wires or possible defects. Insulation covering flexible cords, such as extension cords, is particularly vulnerable to damage.
Insulation covering conductors in non-construction settings is regulated by 29 CFR 1910.302 through 1910.308, Wiring Design and Protection. Subpart S generally requires insulation on circuit conductors. It also specifies that the insulation used should be suitable for the voltage and conditions. Conductors used in construction applications are regulated by 29 CFR 1926.402 through 1926.408.
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2-1. To be effective as insulation, what criteria must be met?
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