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A ground fault circuit interrupter (GFCI) outlet is a special type of circuit breaker that can automatically shut off power directly at the outlet when it detects an electrical fault. GFCI outlets should be installed in any potentially wet or damp areas such as kitchens, bathrooms, laundry rooms, outdoors, basements, garages and workshops. Damp areas can make you prone to dangerous electric shock but using a GFCI outlet can greatly reduce your risk of injury.
This guide will teach you how to wire a GFCI outlet and how to install GFCI outlets safely.
Why Install a GFCI Outlet?
The National Electrical Code (NEC) requires GFCI outlets in all wet or damp locations. For your home to be up to code, working GFCI outlets must be installed in your bathrooms, kitchens and laundry rooms. Plus, installing a GFCI outlet reduces the risk of electric shock, helping ensure the safety of you and your family.
In many homes, necessary circuit breakers and GFCIs are already installed, but they can stop working unexpectedly, so it is important to know how to replace GFCI outlets when this happens. GFCIs should be tested monthly to ensure they are providing protection. Press the TEST button, then the RESET button. If the indicator light does not go out and come back on, or if the GFCI cannot be reset, it must be replaced.
Safety Tip: Don’t use a GFCI outlet as a receptacle for a refrigerator or a freezer, as it could trip without your knowledge.
Turn Off the Power
- Turn off power at the circuit breaker or fuse.
- Place a note at the electrical panel to warn others not to turn it on while you are working on this project.
- Use a voltage tester to verify power is shut off.
Safety Tip: Wear rubber-soled shoes and use tools with rubber handles when working with electrical wiring.
Remove the Existing Outlet
- Use a screwdriver or drill to remove the wall plate.
- Remove mounting screws and gently pull the switch out of the wall box.
- If replacing an existing GFCI, label the black and white wires on the Line and Load terminals.
- Disconnect wires from the existing outlet.
- Prepare wires by making sure they are straight and not touching each other. Cut with wire trimmers if necessary.
- Use wire strippers to remove the wire insulation so 3/4-inch of the copper conductor is showing.
Tip: Take a picture of the wiring on the current outlet before disconnecting the wires in case you need to refer to it later.
Identify the Line Wires
- Pull wires out of the wall box and position them so they cannot touch each other.
- Restore power.
- Carefully touch the black probe of the voltage tester to the metal box or bare copper ground wire. If installing a GFCI on an ungrounded circuit, refer to the manufacturer's instructions.
- Place the red probe of the voltage tester to each black wire until the tester lights up. This is the black wire that will connect to the Line brass screw terminal.
- Leave the red probe on the black Line hot wire and place the black probe on each white wire until the tester lights up. This is the white wire that will connect to the Line silver screw terminal.
- Turn power off.
Connect the Wires
- Make sure the amp rating of your new GFCI outlet matches the amp rating of the wiring and breaker or fuse.
- Unscrew the terminal screws of the new GFCI outlet until they are difficult to turn.
- Connect the black Line hot wire to the brass screw marked Line by inserting the wire into the back-wire hole. Tighten the terminal screw.
- Connect the white Line neutral wire to the silver screw marked Line by inserting the wire into the back-wire hole. Tighten the terminal screw.
- If the outlet box has four wires plus a ground, connect the second black wire to the brass terminal marked Load and the second white wire to the silver terminal marked Load.
- Connect the ground wire to the green ground screw by inserting the wire into the back-wire hole and tighten the terminal screw. If there are multiple ground wires, connect them together with a copper pigtail, secure with a wire nut and attach the loose end of the pigtail to the green ground screw.
- Always attach black to black and white to white.
- For extra protection, you can wrap the GFCI wiring connections with electrical tape.
Place the GFCI into the Wall Box
- Carefully bend the wires and push the GFCI into the wall box.
- Tighten the mounting screws to secure the GFCI to the wall box.
Cover with the Wall Plate
- Install the wall plate.
- Restore power.
- Press the RESET button on the GFCI.
- If the GFCI does not reset, the line and load leads may have been reversed during installation. Refer to the “Test Your Work” section of the manufacturer's instruction sheet or call a qualified electrician.
Knowing how to install GFCI outlets will allow you to replace faulty GFCIs and keep your home safe and up to code. If you are ever in doubt while learning how to wire a GFCI outlet, call a qualified electrician to take care of the job for you. Need help identifying a tool or material for installing GFCI outlets? Find products fast with image search in The Home Depot app. Snap a picture of an item you like, and we'll show you similar products.