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Course 715 - Electrical Safety for Technicians & Supervisors

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

Safe Work Practices


Safe work practices prevent injuries.

For accidents to occur, hazardous conditions and unsafe behaviors must somehow interact. A safe work environment is not enough to control all electrical hazards. You must also work safely. Safe work practices help you control your risk of injury or death from workplace hazards. If you are working on electrical circuits or with electrical tools and equipment, you need to use safe work practices.

Before you begin a task, ask yourself:

  • What could go wrong?
  • Do I have the knowledge, tools, and experience to do this work safely?

All workers should be very familiar with the safety procedures for their jobs. You must know how to use specific controls that help keep you safe. You must also use common sense good sense.

Note: So, why did we strike through "common sense" above? That's because there's no such thing as common sense! We harp on this all the time. You've got to use good sense, and in order to do that, you need to be educated, trained, and experience. There is no way to get around it. Do not assume anyone has common sense: That will get you in trouble and possibly hurt.

Control electrical hazards through safe work practices.

  • Plan your work and plan for safety.
  • Avoid wet working conditions and other dangers.
  • Avoid overhead powerlines.
  • Use proper wiring and connectors.
  • Use and maintain tools properly.
  • Wear correct PPE.

1. For accidents to occur _____ must interact with _____.

a. unsafe actions, existing conditions
b. hazardous conditions, unsafe behaviors
c. people, unsafe situations
d. unsafe conditions, lack of common sense

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Plan Your Work and Plan for Safety


Take time to plan your work, by yourself and with others. Safety planning is an important part of any task. It takes effort to recognize, evaluate, and control hazards. If you are thinking about your work tasks or about what others think of you, it is hard to take the time to plan for safety. But, YOU MUST PLAN.

Planning with others is especially helpful. It allows you to coordinate your work and take advantage of what others know about identifying and controlling hazards. The following is a list of some things to think about as you plan.

  • Work with a buddy-Do not work alone. Both of you should be trained in CPR. Both of you must know what to do in an emergency.
  • Know how to shut off and de-energize circuits-You must find where circuit breakers, fuses, and switches are located. Then, the circuits that you will be working on (even low-voltage circuits) MUST BE TURNED OFF! Test the circuits before beginning work to make sure they are completely de-energized.
  • Plan to lock out and tag out circuits and equipment - Make certain all energy sources are locked out and tagged out before performing any work on an electrical circuit or electrical device. Working on energized ("hot") circuits is one of the most dangerous things any worker could do. If someone turns on a circuit without warning, you can be shocked, burned, or electrocuted. The unexpected starting of electrical equipment can cause severe injury or death.
    • Before ANY work is done on a circuit, shut off the circuit, lock out and tag out the circuit at the distribution panel, then test the circuit to make sure it is de-energized.
    • Before ANY equipment inspections or repairs-even on so-called low-voltage circuits-the current must be turned off at the switch box, and the switch must be padlocked in the OFF position. At the same time, the equipment must be securely tagged to warn everyone that work is being performed. Again, test circuits and equipment to ensure they are de-energized.
    • No two locks should be alike. Each key should fit only one lock, and only one key should be issued to each worker. If more than one worker is working on a circuit or repairing a piece of equipment, each worker should lock out the switch with his or her own lock and never permit anyone else to remove it. At all times, you must be certain that you are not exposing other workers to danger. Workers who perform lock-out/tag-out must be trained and authorized to repair and maintain electrical equipment. A locked-out switch or feeder panel prevents others from turning on a circuit. The tag informs other workers of your action.
  • Remove jewelry and metal objects - Remove jewelry and other metal objects or apparel from your body before beginning work. These things can cause burns if worn near high currents and can get caught as you work.
  • Plan to avoid falls - Injuries can result from falling off scaffolding or ladders. Other workers may also be injured from equipment and debris falling from scaffolding and ladders.
  • Do not do any tasks that you are not trained to do or that you do not feel comfortable doing!

2. When working on electrical circuits, even low-voltage circuits, the circuits must be _____.

a. de-energized
b. turned on
c. tagged
d. energized

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Case Study

Lockout/Tagout would have prevented this fatality.

A worker was attempting to correct an electrical problem involving two non-operational lamps. He examined the circuit in the area where he thought the problem was located.

He had not shut off the power at the circuit breaker panel and did not test the wires to see if they were live. He was electrocuted when he grabbed the two live wires with his left hand.

He collapsed to the floor and was found dead.

The fatality in this accident would not have occurred if the following safe work practices had been followed:

  • Employers should not allow work to be done on electrical circuits unless an effective lock-out/tag-out program is in place.
  • No work should be done on energized electrical circuits. Circuits must be shut off, locked out, and tagged out. Even then, you must test the circuit before beginning work to confirm that it is de-energized ("dead").

3. Unless you are authorized to work on energized circuits, you must do each of the following prior to working on electrical circuits EXCEPT _____.

a. shut off the circuit
b. lock/tag out the circuit as required
c. check the circuit's drawing (schematic)
d. test the circuit to make sure it's dead

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Overhead and Underground Powerlines

Hoisting operations near powerlines.

Overhead Powerlines

Be very careful not to contact overhead powerlines or other exposed wires. More than half of all electrocutions are caused by contact with overhead lines. When working in an elevated position near overhead lines, avoid locations where you (and any conductive object you hold) could contact an unguarded or uninsulated line. You should be at least 10 feet (3.05 meters) away from high-voltage transmission lines.

Vehicle operators should also pay attention to overhead wiring. Dump trucks, front-end loaders, and cranes can lift and make contact with overhead lines. If you contact equipment that is touching live wires, you will be shocked and may be killed. If you are in the vehicle, stay inside. Always be aware of what is going on around you.


Underground Powerlines

Underground powerlines present a different set of hazards. Workers digging with heavy equipment or using power tools are injured most frequently by inadvertent exposure to live underground powerlines.

Be sure that you call the local utility company to submit a "locate request" before digging. The federally-regulated "call before you dig" number is 811. Locate crews will mark your dig site within a few days so that you know where to avoid digging. Always dig around the marks/flags, not on them.

4. When performing hoisting operations, keep at least _____ away from high-voltage transmission lines.

a. 3 feet
b. 10 feet
c. 12 feet
d. 20 feet

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Use Proper Wiring and Connectors

Use the following best practices when working with wiring and connectors:

  • Avoid overloads - Do not overload circuits.
  • Test GFCIs - Test GFCIs monthly using the "test" button.
  • Check switches and insulation - Tools and other equipment must operate properly. Make sure that switches and insulating parts are in good condition.

  • Use three-prong plugs - Never use a three-prong grounding plug with the third prong broken-off. When using tools that require a third-wire ground, use only three-wire extension cords with three-prong grounding plugs and three-hole electrical out-lets. Never remove the grounding prong from a plug! You could be shocked or expose someone else to a hazard. If you see a cord without a grounding prong in the plug, remove the cord from service immediately.

  • Use extension cords properly - If an extension cord must be used, choose one with sufficient ampacity for the tool being used. An undersized cord can overheat and cause a drop in voltage and tool power. Check the tool manufacturer's recommendations for the required wire gauge and cord length. Make sure the insulation is intact. To reduce the risk of damage to a cord's insulation, use cords with insulation marked "S" (hard service) rather than cords marked "SJ" (junior hard service). Make sure the grounding prong is intact. In damp locations, make sure wires and connectors are waterproof and approved for such locations. Do not create a tripping hazard.

5. What should you do if you see an extension cord with the ground prong missing?

a. Connect it only to two-prong outlets
b. Stick another prong into the plug and continue using it
c. Remove the extension cord from service
d. Nothing, it's not a hazard if the prong is missing

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Use Proper Wiring and Connectors (Continued)

Use the following best practices when working with wiring and connectors:

  • Check power cords and extensions - Electrical cords should be inspected regularly using the following procedure:
    1. Remove the cord from the electrical power source before inspecting.
    2. Make sure the grounding prong is present in the plug.
    3. Make sure the plug and receptacle are not damaged.
    4. Wipe the cord clean with a diluted detergent and examine for cuts, breaks, abrasions, and defects in the insulation.
    5. Coil or hang the cord for storage. Do not use any other methods. Coiling or hanging is the best way to avoid tight kinks, cuts, and scrapes that can damage insulation or conductors.
  • You should also test electrical cords regularly for ground continuity using a continuity tester as follows:
    1. Connect one lead of the tester to the ground prong at one end of the cord.
    2. Connect the second lead to the ground wire hole at the other end of the cord.
    3. If the tester lights up or beeps (depending on design), the cord's ground wire is okay. If not, the cord is damaged and should not be used.
  • Do not pull on cords - Always disconnect a cord by the plug.
  • photo68a
    Use correct connectors - Use electrical plugs and receptacles that are right for your current and voltage needs. Connectors are designed for specific currents and voltages so that only matching plugs and receptacles will fit together. This safeguard prevents a piece of equipment, a cord, and a power source with different voltage and current requirements from being plugged together. Standard configurations for plugs and receptacles have been established by the National Electric Manufacturers Association (NEMA).

6. Which of the following is a safe work practice when using electrical wiring and connectors?

a. Inspect the cord while energized to ensure continuity
b. If the ground prong is missing, insert a new one
c. Never coil or hang cords for storage
d. Always disconnect a cord by the plug

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Use and Maintain Hand and Power Tools Properly

Hand and power tools are a common part of our everyday lives and are present in nearly every industry. These tools help us to easily perform tasks that otherwise would be difficult or impossible. However, these simple tools can be hazardous and have the potential for causing severe injuries when used or maintained improperly. Special attention toward hand and power tool safety is necessary in order to reduce or eliminate these hazards.

Your tools are at the heart of your craft. Tools help you do your job with a high degree of quality. Tools can do something else, too. They can cause injury or even death! You must use the right tools for the job. Proper maintenance of tools and other equipment is very important. Inadequate maintenance can cause equipment to deteriorate, creating dangerous conditions. You must take care of your tools so they can help you and not hurt you.

  • Inspect tools before using them - Check for cracked casings, dents, missing or broken parts, and contamination (oil, moisture, dirt, corrosion). Damaged tools must be removed from service and properly tagged. These tools should not be used until they are repaired and tested.
  • Use the right tool correctly - Use tools correctly and for their intended purposes. Follow the safety instructions and operating procedures recommended by the manufacturer. When working on a circuit, use approved tools with insulated handles.


  • Protect your tools - Keep tools and cords away from heat, oil, and sharp objects. These hazards can damage insulation. If a tool or cord heats up, stop using it! Report the condition to a supervisor or instructor immediately. If equipment has been repaired, make sure that it has been tested and certified as safe before using it. Never carry a tool by the cord. Disconnect cords by pulling the plug-not the cord!
  • Use double-insulated tools - Portable electrical tools are classified by the number of insulation barriers between the electrical conductors in the tool and the worker. The NEC permits the use of portable tools only if they have been approved by Underwriter's Laboratories (UL Listed). Equipment that has two insulation barriers and no exposed metal parts is called double-insulated. When used properly, double-insulated tools provide reliable shock protection without the need for a third ground wire. Power tools with metal housings or only one layer of effective insulation must have a third ground wire and three-prong plug.
  • Use multiple safe practices - Remember: A circuit may not be wired correctly. Wires may contact other "hot" circuits. Someone else may do something to place you in danger. Take all possible precautions.

Read more about and power tool safety

7. When used properly, double-insulated tools provide reliable shock protection without the need for a _____.

a. third ground wire
b. lockout device
d. insulation test

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Be Sure Neutral Wires Are Not Open

An open neutral is the most dangerous and unknown hazard a worker can encounter when it's line is not de-energized. It’s important to understand that in a 3-phase electrical system, all three phases must be verified as de-energized or there may be the potential for a shock. The neutral circuit wire (usually white) is grounded, but is under a load and the source of the neutral current cannot always be identified.

If a grounded (neutral) service conductor which serves as the effective ground-fault current path is opened, a ground fault cannot be cleared and the metal parts of electrical equipment, as well as metal piping and structure steel will become and remain energized providing the potential for electric shock.

Potential hazards include:

  • Breaking a neutral under load can create a shock hazard.
  • Workers contacting a lifted neutral potentially provide an alternative path to ground.
  • A broken neutral or lifted neutral can result in a shock or an arc.

For instance, in 2005 a worker received a shock after lifting a neutral from its bus bar. The neutral received its power through an emergency light that received power from another distribution panel.

Case Study

An employee was climbing a metal ladder to hand an electric drill to the journeyman installer on a scaffold about 5 feet above him. When the victim reached the third rung of the ladder, he received an electrical shock that killed him. An investigation showed that the grounding prong was missing from the extension cord attached to the drill. Also, the cord's green grounding wire was, at time, contacting the length of the grounding wire and the drill's frame became energized. The drill was not double-insulated.

To avoid deadly incidents like this one, take these precautions:

  • Make certain the approved GFCIs or equipment grounding systems are used at construction sites.
  • Use equipment that provides a permanent and continuous path to ground. Any fault current will be safely diverted along the path.
  • Inspect electrical tools and equipment daily and remove damaged and defective equipment from use right away.

8. If you see a loose white wire on an energized circuit, what does it mean?

a. A possible short circuit of the hot wire: possible problem
b. An open neutral wire: could be very dangerous
c. An open ground wire: not a problem
d. It's a one-phase circuit: not a problem

Next Section

Wear Correct PPE

OSHA requires that you be provided with personal protective equipment. This equipment must meet OSHA requirements and be appropriate for the parts of the body that need protection and the work performed. There are many types of PPE: rubber gloves, insulating shoes and boots, face shields, safety glasses, hard hats, etc. Even if laws did not exist requiring the use of PPE, there would still be every reason to use this equipment. PPE helps keep you safe. It is the last line of defense between you and the hazard.

  • Wear safety glasses - Wear safety glasses to avoid eye injury.
  • Wear proper clothing - Wear clothing that is neither floppy nor too tight. Loose clothing will catch on corners and rough surfaces. Clothing that binds is uncomfortable and distracting.
  • Contain and secure loose hair - Wear your hair in such a way that it does not interfere with your work or safety.
  • Wear proper foot protection - Wear shoes or boots that have been approved for electrical work. (Tennis shoes will not protect you from electrical hazards.) If there are non-electrical hazards present (nails on the floor, heavy objects, etc.), use footwear that is approved to protect against these hazards as well.
  • Wear a hard hat - Wear the appropriate class A/G or B/E hard hat to protect your head from bumps, falling objects and electrical hazards. Do not wear Class C hard hats. Hard hats should be worn with the bill forward to protect you properly.
  • Wear hearing protectors - Wear hearing protectors in noisy areas to prevent hearing loss.
  • Follow directions - Follow the manufacturer's directions for cleaning and maintaining PPE.
  • Make an effort - Search out and use any and all equipment that will protect you from shocks and other injuries.

9. Which of the following is considered electrical protective equipment?

a. R23 hearing protection
b. Class C Hard hat
c. Rubber insulating gloves
d. UL-approved safety glasses

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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