Electrical Safety

Electrical hazards can cause burns, shocks and electrocution (death).

  • Assume that all overhead wires are energized at lethal voltages. Never assume that a wire is safe to touch even if it is down or appears to be insulated.
  • Never touch a fallen overhead power line. Call the electric utility company to report fallen electrical lines.
  • Stay at least 10 feet (3 meters) away from overhead wires during cleanup and other activities. If working at heights or handling long objects, survey the area before starting work for the presence of overhead wires.
  • If an overhead wire falls across your vehicle while you are driving, stay inside the vehicle and continue to drive away from the line. If the engine stalls, do not leave your vehicle. Warn people not to touch the vehicle or the wire. Call or ask someone to call the local electric utility company and emergency services.
  • Never operate electrical equipment while you are standing in water.
  • Never repair electrical cords or equipment unless qualified and authorized.
  • Have a qualified electrician inspect electrical equipment that has gotten wet before energizing it.
  • If working in damp locations, inspect electric cords and equipment to ensure that they are in good condition and free of defects, and use a ground-fault circuit interrupter (GFCI).
  • Always use caution when working near electricity.

We rely on electricity, but sometimes underestimate its capability of causing injury. Even household current (120 volts) can stop your heart. UW personnel need to be aware of the hazards electricity poses, such as shock, fire and explosion, and either eliminate or control those hazards.


Electrical shock happens when current passes through the body. Electricity travels through closed circuits, and people, sometimes tragically, can become part of the circuit. When a person receives a shock, electricity flows between parts of the body or through the body to a ground. This can happen if someone touches both wires of an energized circuit, touches one wire of the circuit while standing unprotected or touches a metal part that has become energized.

Electrocution refers to the injury or lethal dose of electrical energy. Electricity can also cause forceful muscle contraction or falls. The severity of injury depends on the amount of current flowing through the body, the current’s path through the body, the length of time the body remains in the circuit and the current’s frequency.


Electrical fires may be caused by excessive resistance that generates heat from any of the following:

  • Too much current running through wiring where overcurrent protection fails or does not exist
  • Faulty electrical outlets resulting in poor contact or arcing
  • Poor wiring connections and old wiring that is damaged and cannot support the load

An explosion can occur when electricity ignites a flammable gas or combustible dust mixture in the air. Ignition from a short circuit or static charge is possible.

What you need to know

Electrical Safety Basics

  • Don’t work with exposed conductors carrying 50 volts or more.
  • Make sure electrical equipment is properly connected, grounded and in good working order.
  • Extension cords may not be used as permanent wiring and should be removed after temporary use for an activity or event.
  • Surge suppressors with built-in circuit breakers may be used long-term and are available with three, six and 15 foot-long cords.
  • High amperage equipment such as space heaters, portable air conditioners and other equipment must be plugged directly into permanent wall receptacles.
  • Do not access, use or alter any building’s electrical service, including circuit breaker panels, unless you are specifically qualified and authorized to do so.
  • Wet environments can increase the risk of an electrical shock.

For more information on electrical cords, including extension cords and power taps, see the Extension Cords, Surge Suppressors and Power Strips Focus Sheet.

Housekeeping and Maintenance

  • Maintain at least 30 inches of clearance in front of electrical panels to ensure a safe environment for facilities workers.  
  • Make sure that all junction boxes are covered.

What you can do to stay safe

Avoid Activities That Requires Training 

  • Working with exposed conductors carrying 50 volts or more
  • Making repairs or alterations to any electrical equipment
  • Opening up the case, or removing barrier guards, of any equipment that utilizes electricity
  • Using any tools or a meter to measure for the presence of electricity
  • Resetting a tripped circuit breaker, or replace a blown fuse

Ask a qualified person to perform these tasks.


To prevent electrical hazards, always make sure equipment is properly grounded. Electrical grounding provides an alternate path for electricity to follow, rather than going through a person. Equipment with a grounding prong must be plugged into an extension cord with a ground; the grounding plug should not be removed from the equipment. 

Wet Locations

When using electricity in a wet or damp location, including outdoor locations, a Ground Fault Circuit Interrupter (GFCI) must be used. The GFCI ensures that any electrical shock is brief. Although painful, it wouldn’t be fatal because the GFCI creates a ground fault or leak in the current.

Additional information about GFCI devices can be found in the Ground Fault Circuit Interrupter Focus Sheet.


When servicing and maintenance tasks involve electricity and electrical equipment, you must prevent the unexpected startup of equipment. More information on lockout/tagout procedures is available on the Hazardous Energy Control page.

Arc Flash

An arc flash (also called a flashover), which is distinctly different from the arc blast, is part of an arc fault, a type of electrical explosion or discharge that results from a low-impedance connection through air to ground or another voltage phase in an electrical system.(wiki)


A ground fault circuit interrupter (GFCI), also called Ground Fault Interrupter (GFI) or Residual Current Device (RCD) is a device that shuts off an electric power circuit when it detects that current is flowing along an unintended path, such as through water or a person. (wiki)


In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth. (wiki)

What is a sample checklist for basic electrical safety?

Inspect Cords and Plugs

  • Check extension cords and plugs daily. Do not use, and discard if worn or damaged. Have any extension cord that feels more than comfortably warm checked by an electrician.

Eliminate Octopus Connections

  • Do not plug several items into one outlet.
  • Pull the plug, not the cord.
  • Do not disconnect power supply by pulling or jerking the cord from the outlet. Pulling the cord causes wear and may cause a shock.

Never Break OFF the Third Prong on a Plug

  • Replace broken 3-prong plugs and make sure the third prong is properly grounded.

Never Use Extension Cords as Permanent Wiring

  • Use extension cords only to temporarily supply power to an area that does not have a power outlet.
  • Keep extension cords away from heat, water and oil. They can damage the insulation and cause a shock.
  • Do not allow vehicles to pass over unprotected extension cords. Extension cords should be put in protective wire way, conduit, pipe or protected by placing planks alongside them.


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