February 2006

What's This?

Ground Fault Circuit Interrupter

You've probably heard the saying “Water and electricity don't mix.” A ground fault circuit interrupter (GFCI) helps make sure that doesn't happen.

Ground fault circuit interrupter outlets are perfect for retrofitting older homes that don't have this life-saving device.  Install GFCIs in wet or damp locations inside the home.

A GFCI shuts off the flow of electricity when it detects electric current may be leaking out of a circuit. This leakage could be the result of electricity flowing through a person instead of its intended route, electric wires.

If you use a power tool in the rain, water can provide a path for electricity to leak out from the tool into your body. The same thing can happen if someone drops an electrical appliance, like a radio or hairdryer, in a bathtub filled with water.

The GFCI measures the current flowing out from the source on the hot wire and returning to the source on the neutral wire.  If it detects a difference between the two, it shuts off power in as quickly as one-thirtieth of a second.

A GFCI can sense a current imbalance of as little as five milliamps (.005 amp).  For comparison, a 60-watt light bulb draws one-half amp (.5 amp) when it burns.

Do you need a GFCI if the outlet or extension cord is equipped with a third prong?  Yes! The third prong protects equipment and the electrical system.   It may prevent a fire or stop a short circuit, but it's not quick or sensitive enough to prevent electric shock.

The National Electric Code (NEC) now requires GFCIs in any location where it might be wet, damp or where the user could be in direct contact with the earth.

Specifically, GFCIs are required in kitchens, bathrooms, garages, crawlspaces and unfinished basements. They should also be installed near laundry sinks, wet bars, hot tubs, saunas and pools. Outlets outside your home or in outbuildings also require GFCI protection.

Portable ground fault circuit interrupters are a good idea when using electrical devices outdoors.

If your home was built prior to 1993, you may not have adequate GFCI protection. The NEC phased in different GFCI requirements over several years. But getting your home up to snuff is not that difficult or expensive.

GFCIs are available in different configurations. Your electrician can install a GFCI breaker in your home's service entrance panel to protect an entire circuit. To protect a single receptacle and all receptacles downstream on the same circuit, install a GFCI outlet.

If you're somewhere you can't make a permanent fix, special extension cords are available with GFCIs built in.  Use one any time you're working outdoors or in a damp location and are unsure if the circuit you're using is protected.

Just installing the GFCI doesn't mean the job's finished. All GFCIs, whether breakers, outlets or extension cords, have test buttons to ensure the device is working properly.   Test all GFCIs at least every month.

More Information:  Consumer Products Safety Commission

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