GFCI vs AFCI Breakers — What's the Difference?

GFCI — Ground Fault Circuit Interrupter

A GFCI detects current leaking to ground — which can happen when electricity flows through a person. It monitors the difference between the current on the hot wire and the neutral wire. If there is a difference of more than 5 milliamps (indicating current is taking an unintended path — possibly through a person), it trips within 1/40th of a second.

GFCI protects against: electrocution from ground faults, especially in wet locations.

NEC requires GFCI in: bathrooms, kitchens (within 6 feet of a sink), garages, outdoors, crawl spaces, unfinished basements, boathouses, and near swimming pools.

AFCI — Arc Fault Circuit Interrupter

An AFCI detects the electrical signature of arcing — electricity jumping across a gap in damaged or loose wiring. Arcing can smolder inside walls for hours before starting a fire, and a standard breaker will not trip because the arc current may be below the trip threshold.

AFCI protects against: electrical fires caused by damaged wiring, loose connections, and worn insulation.

NEC requires AFCI in: bedrooms, living rooms, dining rooms, family rooms, parlors, libraries, dens, sunrooms, recreation rooms, closets, hallways, laundry areas, and all other rooms in a dwelling unit (2020 NEC).

Dual-Function AFCI/GFCI Breakers

A dual-function breaker provides both AFCI and GFCI protection in a single unit. This is the most comprehensive protection available and is required in some locations where both types of protection are mandated.

Dual-function breakers are available from Square D (QO), Eaton (BR, CH), Siemens, and GE for most residential panels.

GFCI Outlet vs. GFCI Breaker

GFCI protection can be provided by either a GFCI outlet (at the first outlet in the run, protecting all downstream outlets) or a GFCI breaker (protecting the entire circuit from the panel). A GFCI breaker is more comprehensive but more expensive. A GFCI outlet is less expensive but only protects outlets downstream of it.

Which One Do You Need?

Bathroom, kitchen, garage, outdoor, or wet location: GFCI Bedroom, living room, or other living space: AFCI Both types required in the same location: Dual-function AFCI/GFCI Unsure: install dual-function — it covers both requirements