Basic Electrical Safety

Surge suppressor with overcurrent protection

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.

Shock

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.

Fire/Explosion

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 require 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
Reseting a tripped circuit breaker, or replace a blown fuse

Ask a qualified person to perform these tasks.

Grounding

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.

Lockout/Tagout

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.

Services available

EH&S provides the following services:

Consultation on basic electrical safety
Advice on safe work practices for energized circuits and parts, or high voltage electrical transmission and distribution systems
Investigation of accidents and injuries to help educate and prevent recurrence

All injuries and near-misses, including those potentially caused by electricity or electrical equipment, must be reported using the Online Accident Reporting System (OARS).

More information

Glossary

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)