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Course 715 - Electrical Safety for Technicians & Supervisors

Safety guides and audits to make your job as a safety professional easier
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Evaluating Your Risk

Introduction

After you recognize a hazard, your next step is to evaluate your risk from the hazard. The closer you work to the "danger zone," the more likely you'll be exposed to the electrical hazard. For instance, exposed wires should be recognized as a hazard. If the exposed wires are 15 feet off the ground, you're not close to the danger zone so the 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. It's important that as you work throughout the day, you must constantly evaluate your risk.

Another factor increasing your risk of injury is working around combinations of hazards. 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 may be important clues that electrical hazards exist. For example, if a GFCI keeps tripping while you are using a power tool, that's a clue that 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.

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.

1. Working with a defective electrical tool on wet ground would be an example of increased risk due to _____.

a. work on a construction site
b. location to the hazard
c. a combination of hazards
d. a single hazard type

Next Section

Case Study

An 18-year-old male worker had just completed mopping the floor 10 minutes earlier and was plugging a toaster into a floor outlet when he received a shock. 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.

By the time the circuit was turned off, the victim had been exposed to the current for 3 to 8 minutes. The manager and the employee left the victim to unlock the front door and call for help. Another employee found that the victim no longer had a pulse. The employee began administering CPR, which was continued by the rescue squad for 90 minutes, but unfortunately the victim was dead on arrival at a local hospital.

The 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 damp or wet areas!
  • Know the location of circuit breakers for your work area.

2. What would prevent electrocution should a worker be exposed to electrical current while working in a damp location?

a. Circuits equipped with GFCI protection
b. Circuit breakers removed
c. Warning signs in wet areas
d. Use of extension cords

Next Section

Conditions that Point to Electrical Hazards

There are a number of other conditions that indicate an electrical 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.

3. Tripped circuit breakers and blown fuses show that _____.

a. the voltage is high
b. too little resistance
c. too much current is flowing
d. the a.c. frequency is too high

Next Section

Case Study

A 20-year-old male laborer was carrying a 20-foot piece of iron from a welding shop to an outside storage rack. As he was turning a corner near a bank of electrical transformers, the top end of the piece of iron struck an uninsulated supply wire at the top of a transformer. Although the transformers were surrounded by a 6-foot fence, they were about 3 feet taller than the fence enclosure. Each transformer carried 4,160 volts. When the iron hit the supply wire, the laborer was electrocuted. A forklift operator heard the iron drop to the ground at about 8:46 a.m. and found the victim 5 minutes later. He was pronounced dead on arrival at a local hospital.

According to OSHA, this fatality would not have occurred if:

  • The enclosure around the fence was too low. The fence should have been at least 8 feet tall.
  • The company in this case did not offer any formal safety training to its workers. All employers should develop safety and health training programs so their employees know how to recognize and avoid life-threatening hazards.

4. A wall, screen, or fence around electrical installations must provide a degree of isolation equivalent to _____.

a. a distance of 6 feet (1.8 m)
b. at least an 8-foot (2.44 m) fence
c. a GFCI-protected isolation of 600 v
d. a lock and key mechanism

Check your Work

Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.

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