Contact with Power Lines.
A. Fatal electrocution is the main risk, but burns and falls from elevations are also hazards.
B. Contact utilities for buried power line locations.
C. De-energize and ground lines when working near them. Other protective measures include guarding or insulating the lines.
Lack of Ground-Fault Protection.
A. Normal use of electrical equipment at your site causes wear and tear that results in insulation breaks, short-circuits, and exposed wires.
B. Use ground-fault circuit interrupters (GFCIs) on all 120-volt, single-phase, 15- and 20-ampere receptacles, or have an assured equipment grounding conductor program (AEGCP).
C. Visually inspect all electrical equipment before use.
Path to Ground Missing or Discontinuous.
A. If the power supply to the electrical equipment at your site is not grounded or the path has been broken, fault current may travel through a worker's body.
B. Frequently inspect electrical systems to insure that the path to ground is continuous.
C. Do not remove ground prongs from cord- and plug-connected equipment or extension cords.
Equipment Not Used in Manner Prescribed.
A. If electrical equipment is used in ways for which it is not designed, you can no longer depend on safety features built in by the manufacturer.
B. A common misuse of equipment is using modified cords or tools, e.g., removing ground prongs, face plates, insulation, etc.
C. Use all equipment according to the manufacturer's instructions.
Improper Use of Extension and Flexible Cords.
A. Cords that are not 3-wire type, not designed for hard-usage, or that have been modified, increase your risk of contacting electrical current.
B. Use only extension cords that are 3-wire type.
C. Remove cords from receptacles by pulling on the plugs, not the cords.
How Electricity Works.
A. Operating an electrical switch is like turning on a water faucet. The switch's electrical source is a power generating station. A generator provides the pressure for the electrical current to travel through electrical conductors, or wires.
B. Three factors determine the resistance of a substance to the flow of electricity; size, temperature, and material.
C. Substances with very little resistance to the flow of electricity are called conductors. Substances with a high resistance to the flow of electricity are called insulators.
D. When the skin is dry, it is a poor conductor of electrical current. When it is moist, it readily conducts electricity.
How Shocks Occur.
A. Shock results when the body becomes part of the electrical circuit; current enters the body at one point and leaves at another.
B. Metallic parts of electric tools and machines can become energized if there is a break in the insulation of their wiring.
C. Properly installed, the grounding conductor provides protection from electric shock.
How Electrical Current Affects the Human Body.
A. Three primary factors affect the severity of a shock: Amount of current flowing through the body; Path of the current through the body; Length of time the body is in the circuit.
B. Effects can range from a barely perceptible tingle to severe burns and immediate
