Electrical Safety: Safety & Health for Electrical Trades (Student Manual)

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Summary Statement

Student manual on electrical safety with information on recognizing, evaluating and avoiding hazards related to electricity.
January 2002

Safety Model Stage 2—Evaluating Hazards

How Do You Evaluate Your Risk?

After you recognize a hazard, your next step is to evaluate your risk from the hazard. Obviously, exposed wires should be recognized as a hazard. If the exposed wires are 15 feet off the ground, your risk is low. However, if you are going to be working on a roof near those same wires, your risk is high. The risk of shock is greater if you will be carrying metal conduit that could touch the exposed wires. You must constantly evaluate your risk.

Combinations of hazards increase your risk. Improper grounding and a damaged tool greatly increase your risk. Wet conditions combined with other hazards also increase your risk. You will need to make decisions about the nature of hazards in order to evaluate your risk and do the right thing to remain safe.

There are “clues” that electrical hazards exist. For example, if a GFCI keeps tripping while you are using a power tool, there is a problem. Don’t keep resetting the GFCI and continue to work. You must evaluate the “clue” and decide what action should be taken to control the hazard. There are a number of other conditions that indicate a hazard.

  • Tripped circuit breakers and blown fuses show that too much current is flowing in a circuit. This condition could be due to several factors, such as malfunctioning equipment or a short between conductors. You need to determine the cause in order to control the hazard.
  • An electrical tool, appliance, wire, or connection that feels warm may indicate too much current in the circuit or equipment. You need to evaluate the situation and determine your risk.
  • An extension cord that feels warm may indicate too much current for the wire size of the cord. You must decide when action needs to be taken.
  • A cable, fuse box, or junction box that feels warm may indicate too much current in the circuits.
  • A burning odor may indicate overheated insulation.
  • Worn, frayed, or damaged insulation around any wire or other conductor is an electrical hazard because the conductors could be exposed. Contact with an exposed wire could cause a shock. Damaged insulation could cause a short, leading to arcing or a fire. Inspect all insulation for scrapes and breaks. You need to evaluate the seriousness of any damage you find and decide how to deal with the hazard.
  • A GFCI that trips indicates there is current leakage from the circuit. First, you must decide the probable cause of the leakage by recognizing any contributing hazards. Then, you must decide what action needs to be taken.
 Combinations of hazards increase risk.

  • risk—the chance that injury or death will occur
  • Make the right decisions.
  • short—a low-resistance path between a live wire and the ground, or between wires at different voltages (called a fault if the current is unintended)

  • Any of these conditions, or “clues,” tells you something important: there is a risk of fire and electrical shock. The equipment or tools involved must be avoided. You will frequently be caught in situations where you need to decide if these clues are present. A maintenance electrician, supervisor, or instructor needs to be called if there are signs of overload and you are not sure of the degree of risk. Ask for help whenever you are not sure what to do. By asking for help, you will protect yourself and others.

    Summary of Section 6

    Look for “clues” that hazards are present.

    Evaluate the seriousness of hazards.

    Decide if you need to take action.

    Don’t ignore signs of trouble.

    An 18-year-old male worker, with 15 months of experience at a fast food restaurant, was plugging a toaster into a floor outlet when he received a shock. Since the restaurant was closed for the night, the floor had been mopped about 10 minutes before the incident. The restaurant manager and another employee heard the victim scream and investigated. The victim was found with one hand on the plug and the other hand grasping the metal receptacle box. His face was pressed against the top of the outlet. An employee tried to take the victim’s pulse but was shocked. The manager could not locate the correct breaker for the circuit. He then called the emergency squad, returned to the breaker box, and found the correct breaker. By the time the circuit was opened (turned off), the victim had been exposed to the current for 3 to 8 minutes. The employee checked the victim’s pulse again and found that it was very rapid.

    The manager and the employee left the victim to unlock the front door and place another call for help. Another employee arrived at the restaurant and found that the victim no longer had a pulse. The employee began administering CPR, which was continued by the rescue squad for 90 minutes. The victim was dead on arrival at a local hospital.

    Later, two electricians evaluated the circuit and found no serious problems. An investigation showed that the victim’s hand slipped forward when he was plugging in the toaster. His index finger made contact with an energized prong in the plug. His other hand was on the metal receptacle box, which was grounded. Current entered his body through his index finger, flowed across his chest, and exited through the other hand, which was in contact with the grounded receptacle.

    To prevent death or injury, you must recognize hazards and take the right action.
    • If the circuit had been equipped with a GFCI, the current would have been shut off before injury occurred.

    • The recent mopping increased the risk of electrocution. Never work in wet or damp areas!