How to Install a Ground Fault Circuit Breaker

Electrician Working on GFCI in Kitchen - 185268524
Getty / Pamela Moore

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, and 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.

A GFCI breaker installs much like a standard single-pole circuit breaker, but there are some important differences to be aware of. Also, the new GFCI breaker must be the proper type and brand for the service panel. 

Warning: Installing a circuit breaker involves working near equipment carrying deadly levels of electrical current. 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 terminals on the main breaker will remain live at all times. Never touch the service lines or the main breaker terminals while working in the service panel. 

Choosing the Right GFCI Breaker

Service panels and breakers are made by many different manufacturers, and panels and breakers are not universally compatible. When installing a new breaker, the breaker must be compatible with 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. Standard branch circuits are rated for 120 volts and either 15 or 20 amps. Circuits rated for 15 amps usually have 14-gauge wiring but may have 12-gauge wiring; both are permissible.

A 15-amp circuit must be protected by a 15-amp breaker. Circuits rated for 20 amps must have 12-gauge or larger circuit wiring and must be protected by a 20-amp breaker. Never use a 20-amp breaker on a 15-amp circuit.

Difference Between Standard and GFCI Breakers

Both standard and GFCI breakers are single-pole breakers that occupy one slot on a service panel and connect to one "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. With a GFCI breaker, the neutral circuit wire connects to the neutral terminal on the breaker. Most GFCI breakers also have a short, coiled, white neutral wire preinstalled on the breaker; this connects to the neutral bus on the panel.

Note: You must connect the hot circuit wire to the "hot" or "load" terminal on the GFCI breaker and connect the neutral circuit wire to the neutral terminal on the breaker. 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.

How To Install a GFCI Breaker

The most important step for this project is shutting off the power to the service panel by switching off the main breaker. This 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 terminals they connect to on the main breaker. These wires and 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. Here are the basic steps for installing a new GFCI breaker in an open slot on the service panel:

  1. Open the service panel door and switch the main breaker to the OFF position.
  2. Remove the panel cover ("dead front cover") without touching any wires inside the panel.
  1. Confirm that the power is off inside the panel, using a non-contact voltage tester.
  2. Remove one of the knockout plates on the panel cover, if necessary, to create an opening for the new GFCI breaker.
  3. Switch the new GFCI breaker to the OFF position.
  4. Connect the hot circuit wire to the "HOT" or "LOAD" screw terminal on the GFCI breaker.
  5. Connect the neutral circuit wire to the "NEUTRAL" screw terminal on the GFCI breaker.
  6. Connect the GFCI 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.
  7. Snap the GFCI 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.
  8. Reinstall the panel cover (and door, as applicable). Switch the main breaker to the ON position to restore power to the panel.
  9. Test the GFCI breaker as directed by the manufacturer.