Ground-fault circuit-interrupters, or GFCIs, are life-saving devices found on electrical receptacles (outlets), circuit breakers, extension cords, and other electrical equipment. They detect imbalances in the electrical current and quickly shut off the power to minimize the risk of shock. For example, if you're drying your hair in the bathroom and some water splashes into your hairdryer and creates a short circuit, the GFCI outlet will turn itself off—in a tiny fraction of a second. GFCI protection is most commonly required in locations where electricity is likely to come into contact with water.
Different methods of GFCI protection have been available since 1971, and each revision of the National Electrical Code (NEC), which is revised every three years, has expanded the requirements. There are other protective measures built into a wiring system, but GFCI protection is the one that protects against shock and electrocution.
Before You Begin
There are several ways that GFCI protection can be established for an electrical outlet: by replacing a standard receptacle with a GFCI receptacle; by installing a GFCI circuit breaker that protects all devices on the circuit; or by using a GFCI-protected extension cord or power strip.
A GFCI receptacle can be wired so that provides protection for only a single location, or it can be wired so that it also protects other devices "downstream" on the circuit. This allows you to install one GFCI receptacle that also protects others—provided this is allowed by your local code.
While the NEC is the leading authority on all things electrical, your local building authority has the final word on GFCI requirements (and everything else in your house). Check with your local building department for specific rules for installations in your area; in rare instances, local codes may differ from the requirements of the NEC.
Where GFCI Protection Is Required
The National Electrical Code, or NEC, has specific GFCI requirements for dwelling units. Article 210.8 states that ground-fault circuit-interrupters shall be used for all 125-volt, single-phase, 15- and 20-amp receptacles installed in the following locations:
- Bathrooms: All receptacles must be GFCI protected.
- Garages and accessory buildings: GFCI protection must be included on all receptacles in structures that have a floor located at or below grade level, not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use.
- Outdoors: All outdoor receptacles must be GFCI-protected, with one exception: receptacles that are not readily accessible and are supplied by a dedicated branch circuit for electric snow-melting or deicing equipment do not need to be protected.
- Unfinished basements: Unfinished basements are defined as portions or areas of the basement not intended as habitable rooms and limited to storage areas, work areas, etc. Receptacles in these areas must have GFCI protection. Exceptions: GFCI protection is not required for the receptacles supplying only a permanently installed fire alarm or burglar alarm system, receptacles that are not readily accessible, or receptacles on a dedicated branch circuit and labeled for use with plug-in equipment (ex: sump pump).
- Crawl spaces: In unfinished areas located at or below grade level, the same GFCI requirements are in effect as for basements.
- Kitchens: All receptacles serving countertop areas and any receptacle within 6 feet of a sink must have GFCI protection. Also, the receptacle supplying a dishwasher should be GFCI-protected.
- Laundry, utility, and wet bar sinks: Where receptacles are placed within 6 feet of the outside edge of the sink, they require GFCI protection.
- Pool/spa areas: GFCI protection is required for lights and lighting outlets; receptacles for pumps; all receptacles within 20 feet of a pool, spa, or fountain; and power supply for a pool cover.
Equipment / Tools
Installing a GFCI Receptacle
- Non-contact circuit tester
Installing a GFCI-Protected Circuit Breaker
- Non-contact circuit tester or multi-tester
Installing a GFCI Receptacle
- GFCI receptacle
- Wire connectors (if needed)
- Pigtail wires (if needed)
- Masking tape
Installing a GFCI-Protected Circuit Breaker
- GFCI (or GFCI/AFCI) circuit breaker
Using a GFCI-Protected Extension Cord or Power Strip
- GFCI extension cord or power strip
How to Install a GFCI Receptacle
Shut Off Power
To shut off the power to the circuit supplying power to the receptacle you are replacing, flip its circuit breaker to the OFF position at the main service panel. While ideally the circuits should be correctly labeled in the panel, this is not always the case, so make sure to test the outlet with a non-contact circuit tester to make sure the power has been turned off.
Disconnect Old Receptacle
Remove the cover plate on the receptacle, then loosen the mounting screws that hold the receptacle to the electrical box. Gently pull the receptacle out of the box and examine the circuit wires attached to it.
Wiring for a GFCI receptacle is a little different than for a standard receptacle, so it's important that you differentiate between the circuit wires that arrive in the box from "upstream" (from the power source) from the "downstream" wires that continue on to other fixtures on the circuit.
The upstream circuit wires will be connected to screw terminals marked LINE on the new GFCI receptacle, while the downstream wires will connect to screw terminals marked LOAD. Use small tabs of tape to identify the upstream LINE wires and the downstream LOAD wires.
Then, disconnect the old receptacle from all circuit wires and remove it.
Connect the GFCI Receptacle
The method for connecting a GFCI receptacle will vary, depending on whether your goal is single-location protection that protects only a single outlet location, or multi-location protection that also protects devices downstream from the GFCI receptacle. Read the receptacle instructions carefully to determine the correct method of installation.
For single-location protection, the black LINE wire (the upstream hot wire) is connected to the screw terminal marked LINE/HOT on the GFCI receptacle, while the white LINE wire (the upstream neutral wire) is connected to the screw terminal marked LINE/WHITE. The LOAD screws aren't used when the GFCI is wired for single-location protection.
When both upstream and downstream circuit wires pass are present in the box, the proper connection method for single-location protection is to join the GFCI receptacle to the circuit wires by means of white and black pigtail wires, which ensures that uninterrupted power continues downstream to other fixtures.
For multi-location protection, the LOAD screw terminals on the receptacle come into play. Here, the downstream black and white circuit wires are connected to the LOAD screw terminals. Now, the GFCI also protects all devices downstream from the receptacle.
In either scenario, the green grounding screw on the receptacle should be joined to the bare copper circuit grounding wires, either directly to the receptacle's grounding screw or using a pigtail wire if two grounding wires are present in the box.
Make sure to choose a GFCI receptacle that matches the amperage of the circuit: a 20-amp GFCI for a 20-amp circuit, a 15-amp GFCI for a 15-amp circuit.
Test the Circuit
The project concludes by tucking the new GFCI receptacle back into the wall box, replacing the cover plate, and turning the circuit breaker on. The new GFCI receptacle should then be tested by pressing the TEST and RESET buttons on the face of the receptacle.
Because a GFCI receptacle has a much larger body than a standard receptacle, you may occasionally find that the electrical box isn't big enough to handle the larger device. In this instance, it may be necessary to replace the old electrical box with a larger "old work" box.
How to Install a GFCI-Protected Circuit Breaker
A good way to provide GFCI protection to an entire circuit is to replace the standard circuit breaker with a GFCI (or combination GFCI/AFCI) circuit breaker. Installing circuit breakers of any kind is generally a job for a professional electrician since this work involves working inside the home's main service panel, where the full voltage of the entire electrical system is present.
Although the physical process of installing a GFCI circuit breaker is not complicated, the inherent danger of working close to high voltage means this is an advanced project; local regulations may even prohibit you from doing this work yourself. A professional electrician will follow these basic steps to install a GFCI circuit breaker:
Turn Off the Power
The electrician begins the breaker replacement by turning off the power in the service panel by flipping the control lever on the main breaker to the OFF position. Even with this breaker off, the electrician continues to exercise great caution, as the lugs where the main service wires connect in the panel are still live, carrying full voltage.
With the main breaker off, the electrician uses a circuit tester or multimeter to check the hot bus bars and verify that the power to all the circuit breakers is off.
Disconnect the Old Breaker
The electrician now pulls the old standard circuit breaker free of its connection to the hot bus bar running through the panel, then disconnects the hot wire connected to its screw terminal.
The white neutral circuit wire is then disconnected from the neutral bus bar in the panel. The bare copper grounding wire is left connected to the grounding bus bar.
Connect the GFCI Circuit Breaker
The circuit's black hot wire and the white neutral wire are both connected directly to a new GFCI circuit breaker. This is the key difference between a standard breaker and a GFCI breaker: The neutral circuit wire connects directly to the breaker rather than to the neutral bus bar in the panel.
Begin by connecting the white pigtail wire on the GFCI circuit breaker to the neutral bus bar in the service panel. Then, connect the black and white circuit wires to the HOT and NEUTRAL screw terminals, respectively, on the GFCI breaker.
With connections in place, the GFCI breaker is snapped into place in the service panel, and the cover panel is put back into place.
Test the Circuit
The project concludes by turning the service panel's main breaker back on, then testing the GFCI breaker by snapping its TEST and RESET buttons. The entire circuit now has GFCI protection.
How to Use a GFCI-Protected Extension Cord or Power Strip
Temporary protection can be offered by using a power strip or extension cord that has GFCI protection built into it. This can be a good option when you need to plug into a non-GFCI-protected outlet while working in a location where GFCI-protection is advised. For example, if you have no accessible GFCI outlet when working with power tools outdoors, a GFCI-protected extension cord will offer good protection against shock. But remember that a GFCI-protected extension cord or power strip does not meet the NEC circuit requirement—it's only a temporary fix.
Do not confuse a simple surge-protector power strip with a true GFCI power strip. These are different devices. Surge protectors guard against power spikes that can damage sensitive electronic equipment, while GFCIs are specifically designed to protect against shock.
GFCI vs. AFCI Protection
An additional method of wiring protection, the AFCI (arc-fault circuit-interrupter), was mandated by the NEC with the 2017 edition of the Code for all 15-amp and 20-amp 120/125-volt general-use circuits. The rules for AFCI protection are in addition to whatever GFCI requirements exist. As is the case with GFCIs, AFCI protection can be offered by either special circuit breakers or special outlet receptacles.
GFCIs operate by sensing imbalances in current flow, and are best suited for protecting against shock; AFCIs on the other hand, sense tiny sparks, or arcs, in the wiring, and serve to protect against fire. Thus, both GFCI and AFCI protection may be required by Code in many locations.
Although the AFCI requirement applies mostly to new construction, the Code now requires that whenever you are replacing a receptacle in a location that now calls for an AFCI, the new receptacle must be updated to include AFCI protection. This means that whenever you install a GFCI in a 15-amp or 20-amp general-use circuit, the receptacle also needs to include AFCI protection. This can be achieved by installing a special AFCI circuit breaker on the circuit in question, but these are expensive devices. Another solution is to install a special combination AFCI/GFCI dual function receptacle that offers both forms of protection.
Although this may seem confusing, just keep these rules in mind:
- Where a circuit is already protected by an AFCI circuit breaker, you can install a standard GFCI receptacle wherever the Code requires GFCI protection.
- Where a circuit does not have an AFCI breaker, you can install a duel-function AFCI/GFCI receptacle where GFCI protection is needed.
Fortunately, installation of AFCI receptacles or AFCI circuit breakers (or combination GFCI/AFCI devices) is exactly the same as for GFCI-only devices.