GFCIs Fact Sheet

GFCIs Fact Sheet
GFCIs Fact Sheet
http://www.cpsc.gov/cpscpub/pubs/99.html
CPSC Home > Publications > Current
Consumer Product Safety Commission
GFCIs Fact Sheet
CPSC Document #99
THE GFCI
A "GFCI" is a ground fault circuit interrupter. A ground fault circuit interrrupter is an inexpensive
electrical device that, if installed in household branch circuits, could prevent over two-thirds of the
approximately 300 electrocutions still occurring each year in and around the home. Installation of the
device could also prevent thousands of burn and electric shock injuries each year.
The GFCI is designed to protect people from severe or fatal electric shocks Because a GFCI detects
ground faults, it can also prevent some electrical fires and reduce the severity of others by
interrupting the flow of electric current.
THE PROBLEM
Have you ever experienced an electric
shock? If you did, the shock probably
happened because your hand or some
other part of your body contacted a
source of electrical current and your
body provided a path for the electrical
current to go to the ground, so that you
received a shock.
An unintentional electric path between a
source of current and a grounded
surface is referred to as a "ground-fault."
Ground faults ground-fault. Ground
faults occur when current is leaking
somewhere, in effect, electricity is
escaping to the ground. How it leaks is
very important. If your body provides a
path to the ground for this leakage, you
could be injured, burned, severely
shocked, or electrocuted.
Some examples of accidents that
underscore this hazard include the
following:
- Two children, ages five and six, were
electrocuted in Texas when a plugged-in hair dryer fell into the tub in which they were bathing.
- A three-year-old Kansas girl was electrocuted when she touched a faulty countertop.
These two electrocutions occurred because the electrical current escaping from the appliance
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traveled through the victim to ground (in these cases, the grounded plumbing fixtures). Had a GFCI
been installed, these deaths would probably have been prevented because a GFCI would have
sensed the current flowing to ground and would have switched off the power before the electrocution
occurred.
HOW THE GFC1 WORKS
In the home's wiring system, the GFCI constantly monitors electricity flowing in a circuit, to sense any
loss of current. If the current flowing through the circuit differs by a small amount from that returning,
the GFCI quickly switches off power to that circuit. The GFCI interrupts power faster than a blink of an
eye to prevent a lethal dose of electricity. You may receive a painful shock, but you should not be
electrocuted or receive a serious shock injury.
Here's how it may work in your house.. Suppose a bare wire inside an appliance touches the metal
case. The case is then charged with electricity. If you touch the appliance with one hand while the
other hand is touching a grounded metal object, like a water faucet, you will receive a shock. If the
appliance is plugged into an outlet protected by a GFCI, the power will be shut off before a fatal
shock would occur.
AVAILABILITY OF GFCIs
Three common types of ground fault circuit interrupters are available for home use:
* RECEPTACLE TYPE
This type of GFCI is used in place of the standard duplex receptacle found throughout the house It
fits into the standard outlet box and protects you against "ground faults' whenever an electrical
product is plugged into the outlet Most receptacle-type GFCls can be installed so that they also
protect other electri-cal outlets further "down stream" in the branch circuit.
* CIRCUIT BREAKER TYPE
In homes equipped with circuit breakers rather than fuses, a circuit breaker GFCI may be installed in
a panel box to give protection to selected circuits The circuit breaker GFCI serves a dual purpose not only will it shut off electricity in the event of a "ground-fault," but it will also trip when a short circuit
or an ov.er-load occurs Protection covers the wiring and each outlet, lighting fixture, heater, etc
served by the branch circuit protected by the GFCI in the panel box.
* PORTABLE TYPE
Where permanent GFCls are not practical, portable GFCls may be used One type contains the GFCI
circuitry in a plastic encio-sure with plug blades in the back and receptacle slots in the f rant. It can be
plugged into a receptacle, then, the electrical product is plugged into the GFCI. Another type of
portable GFCI is an extension cord combined with a GFCI. It adds flexibility in using receptacles that
are not protected by GFCls.
WHERE GFCIs SHOULD BE CONSIDERED
In homes built to comply with the National Electrical Code
(the Code), GFCI protection is required for most outdoor
receptacles (since 1973), bathroom receptacle circuits (since
1975), garage wall outlets (since 1978), kitchen receptacles
(since 1987), and all receptacles in crawl spaces and
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unfinished basements (since 1990).
Owners of homes that do not have GFCls installed in all those critical areas specified in the latest
version of the Code should consider having them installed. For broad protection, GFCI circuit
breakers may be added in many panels of older homes to replace ordinary circuit breaker. For homes
protected by fuses, you are limited to receptacle or portable-type GFCIs and these may be installed
in areas of greatest exposure, such as the bathroom, kitchen, basement, garage, and outdoor
circuits.
A GFCI should be used whenever operating electrically powered garden equipment (mower, hedge
trimmer, edger, etc.). Consumers can obtain similar protection by using GFCIs with electric tools (drills,
saws, sanders, etc.) for do-it-yourself work in and around the house.
INSTALLING GFCIs
Circuit breaker and receptacle-type GFCIs may be installed in your home by a qualified electrician.
Receptacle-type GFCIs may be installed by knowledgeable consumers familiar with electrical wiring
practices who also follow the instructions accompanying the device. When in doubt about the proper
procedure, contact a qualified electrician. Do not attempt to install it yourself.
The portable GFCI requires no special knowledge or equipment to install.
TESTING THE GFCIs
All GFCIs should be tested once a month to make
sure they are working properly and are protecting
you from fatal shock. GFCIs should be tested after
installation to make sure they are working properly
and protecting the circuit.
To test the receptacle GFCI, first plug a nightlight or
lamp into the outlet. The light should be on Then,
press the "TEST" button on the GFCI. The GFCI's
"RESET" button should pop out, and the light
should go out.
If the "RESET" button pops out but the light does
not go out, the GFCI has been improperly wired.
Contact an electrician to correct the wiring errors.
If the "RESET" button does not pop out, the GFC1
is defective and should be replaced.
If the GFCI is functioning properly, and the lamp
goes out, press the "RESET" button to restore
power to the outlet.
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GPO: 1996 O-169-574
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This document is in the public domain. It may be reproduced without change in part or whole by an
individual or organization without permission. If it is reproduced, however, the Commission would
appreciate knowing how it is used. Write the U.S. Consumer Product Safety Commission, Office of
Information and Public Affairs, Washington, D.C. 20207 or send an e-mail to info@cpsc.gov.
The U.S. Consumer Product Safety Commission is charged with protecting the public from
unreasonable risks of serious injury or death from more than 15,000 types of consumer products
under the agency's jurisdiction. Deaths, injuries and property damage from consumer product
incidents cost the nation more than $700 billion annually. The CPSC is committed to protecting
consumers and families from products that pose a fire, electrical, chemical, or mechanical hazard or
can injure children. The CPSC's work to ensure the safety of consumer products - such as toys, cribs,
power tools, cigarette lighters, and household chemicals - contributed significantly to the 30 percent
decline in the rate of deaths and injuries associated with consumer products over the past 30 years.
To report a dangerous product or a product-related injury, call CPSC's hotline at (800) 638-2772 or
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CPSC email subscription list, please go to www.cpsc.gov/cpsclist.asp. Consumers can obtain this
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