A ground fault circuit breaker is properly called a ground-fault circuit-interrupter breaker, or simply a GFCI breaker. It installs into a home's service panel, or breaker box to provides GFCI protection for the entire branch circuit it serves. This installation is commonly used as an alternative to installing GFCI receptacles (outlets) in specific locations where they are required by the local electrical code. GFCI protection aims at protecting users against accidental shock during circuit failures.
What is a GFCI breaker used for? According to the Energy Education Council: "A ground fault circuit interrupter (GFCI) can help prevent electrocution. If a person’s body starts to receive a shock, the GFCI senses this and cuts off the power before he/she can get injured."
Building codes in most areas now require an additional type of protection against sparking for all general-use outlet circuits, known as AFCI protection. While GFCI protection aims to prevent shock, AFCI protection guards against sparking and resulting fire. Where you need to give a circuit both AFCI and GFCI protection, there are special dual-purpose AFCI/GFCI circuit breakers available, which are installed in the same way as a GFCI-only breaker.
Before You Begin
Service panels and breakers are made by many different manufacturers, and they are not universally compatible. When installing a new breaker, the breaker must match the brand and type of panel you have. Consult the breaker and/or panel manufacturer for recommendations.
The new breaker also must carry the appropriate voltage and amperage ratings for the circuit it will protect. Most standard branch circuits are rated for 120 volts and either 15 or 20 amps. Make sure the new breaker has an amperage size appropriate for the circuit: 15 amps for circuits wired with 14-gauge wire, 20 amps for circuits wired with 12-gauge wire.
Installing a circuit breaker involves working near equipment carrying potentially deadly voltage. While the main circuit breaker and all of the branch circuits in the service panel will be shut off for the GFCI breaker installation, the incoming conductors from the utility service and the lugs (terminals) where the conductors connect to the panel remain live at all times. Never touch the service lines or the lugs while working in the service panel.
Standard vs. GFCI Breakers
Both standard and GFCI breakers are single-pole breakers that occupy one slot on a service panel and connect to the "hot" circuit wire, usually a black wire. The main difference between the two types of breakers involves the neutral connection. With a standard breaker, the neutral circuit wire (usually white) connects to the neutral bus bar on the service panel; it does not connect to the breaker. But with a GFCI or AFCI/GFCI breaker, the neutral circuit wire connects instead to a neutral terminal on the breaker. The GFCI or AFCI/GFCI breaker also has short, coiled, white neutral wire preinstalled on the breaker; this pigtail connects to the neutral bus bar in the service panel.
It's critical that you connect the hot circuit wire to the "hot" or "load" terminal on the GFCI breaker and the neutral circuit wire to the neutral terminal. Mixing these up reverses the polarity of the circuit and may mean the breaker does not provide GFCI protection to the circuit—even if the breaker's test button works normally.
Watch Now: How to Install a Circuit Breaker
Equipment / Tools
- Non-contact voltage tester
- Pliers (as needed)
- GFCI or AFCI/GFCI circuit breaker
This demonstration assumes you are installing a GFCI or AFCI/GFCI breaker for a new electrical circuit. It presumes that the circuit cable has already been routed into the panel and is simply awaiting connection to a new circuit breaker. The process will look a little different if you are disconnecting a standard circuit breaker in order to connect it to a new GFCI or AFCI/GFCI breaker.
Turn off the Power
Open the service panel door and switch the main breaker to the OFF position. Remove the panel cover (called the "dead front cover") without touching any wires inside the panel. Confirm that the power is off inside the panel, using a non-contact voltage tester to check several wires and circuit breakers. Check both terminals on a double-pole breaker, making sure that the breaker is switched ON. The tester should indicate zero voltage for all tests.
Remember: Switching off the main breaker turns off the power to the panel's hot bus bars and to all of the branch circuits. It does not turn off the power to the utility service conductors coming in from the utility meter or the terminal lugs they connect to in the panel. Utility service wires and the main breaker terminals remain live and carry deadly current even when the main breaker is switched off. Never touch the main breaker terminals or the service wires.
Remove a Knockout Plate
Remove one of the knockout plates on the panel cover, if necessary, to create an opening for the new breaker, using pliers.
Connect the GFCI or AFCI/GFCI Breaker
Switch the new breaker to the OFF position. Connect the hot circuit wire to the "HOT" or "LOAD" screw terminal on the breaker, using a screwdriver. Connect the neutral circuit wire to the "NEUTRAL" screw terminal on the breaker.
Connect the breaker's coiled white neutral wire to the neutral bus bar on the service panel. You must use an open screw terminal on the bus bar; do not connect more than one wire to a single terminal. Make sure all of the wire connections are tight.
Install the Breaker
Snap the breaker into the panel as directed by the manufacturer. Most breakers have a notch or foot on the outer end of the breaker that fits into a mounting rail on the outer side of the breaker area in the service panel. The inner end of the breaker snaps into a tab or clip on the panel's hot bus bar.
Test the Breaker
Reinstall the panel cover (and door, as applicable). Turn off all of the branch circuit breakers. Also, turn off any appliances that are supplied by the circuit with the new breaker. Switch the main breaker to the ON position to restore power to the panel, then turn on each of the branch breakers one at a time, including the new GFGI breaker. Test the breaker as directed by the manufacturer. Close the panel door.
When to Call a Professional
Although the technical skills required for installing a GFCI or AFCI/GFCI circuit breaker are fairly simple, the potential for fatal shock means this is a project that you should not attempt if you aren't entirely confident of your DIY electrical skills. And in some areas, local codes do not allow unlicensed homeowners to do this work.
Call a licensed electrician if your code requires it, or if you're not completely confident in your abilities. This is a basic, affordable service call that should take the electrician less than an hour to complete.
Ground Fault Circuit Interrupter. University of Washington.
Ground Fault Circuit Interrupters (GFCIs). University of Illinois Extension's Energy Education Council.
AFCI and GFCI Requirements State-by-State Data. National Association of Home Builders.
Train-the-Trainer: Basic Electricity Safety. Occupational Safety and Health Administration.
CPSC Fact Sheet: What is a GFCI? United States Product Safety Commission.