GFCI vs GFI vs AFCI: What Is the Difference?

Short answer: GFCI and GFI are the same thing. Both names mean a ground fault circuit interrupter, the outlet or breaker that cuts power in a fraction of a second if electricity leaks to the ground, for example through a person. It protects people from shock. An AFCI (arc fault circuit interrupter) does a different job: it cuts power when it detects arcing in the wiring, which protects the house from fire. Most homes need both, in different rooms.

GFCI and GFI: one device, two names

There is no difference between a GFI and a GFCI outlet. GFCI is the term in the National Electrical Code and on the packaging. GFI is the shorter name people use in conversation. If a home inspection report, a contractor or a store shelf says either one, it means the same device.

A GFCI compares the current going out on the hot wire with the current coming back on the neutral. In a healthy circuit they match. If some of the current takes another path to the ground, such as through a person standing on a wet floor, the two no longer match and the GFCI cuts the power. The UL standard for these devices requires them to trip at 6 milliamps or less, well below the level that causes serious harm.

GFCI protection comes in two forms:

• A GFCI outlet. The outlet with the TEST and RESET buttons. It protects itself and, if it is wired that way, every outlet after it on the same circuit. That is why one GFCI in a bathroom can protect a second outlet that has no buttons.
• A GFCI breaker. Installed in the panel, it protects the whole circuit. It is the usual choice when the outlets are hard to reach or when a circuit feeds a hot tub, pool equipment or another outdoor load.

What an AFCI does

An arc is electricity jumping a gap, for example where a nail has nicked a wire inside a wall, where a connection has worked loose, or where a cord has been crushed under furniture. An arc can be hot enough to start a fire inside a wall long before anyone sees smoke. An ordinary breaker does not trip on it, because an arc does not always draw enough current.

An AFCI watches the pattern of the current for the signature of arcing and cuts the power when it finds it. It does nothing to prevent a shock. That is the GFCI’s job.

AFCI protection is almost always a breaker in the panel, because it protects the full length of the wiring on the circuit. AFCI outlets exist for situations where changing the breaker is not practical.

Where each one is required in a home

The National Electrical Code sets the rules, and South Carolina and North Carolina adopt it with their own amendments. Each new edition of the code has added locations, so the rules a home was built to depend on its age. For new work today, the general pattern is:

GFCI protection is required where water and electricity are close together: bathrooms, kitchens, laundry areas, garages and accessory buildings, outdoor outlets, crawl spaces, basements, and outlets near sinks, bathtubs and showers. Equipment such as hot tubs, pool pumps and some appliances also needs it.

AFCI protection is required on the circuits that feed the living spaces of a home: bedrooms, living and family rooms, dining rooms, dens, sunrooms, kitchens, hallways, closets and laundry areas.

Some rooms, such as kitchens and laundry areas, can call for both. A dual-function breaker or outlet covers that in one device.

Your inspector enforces the code edition your city or county has adopted. When we pull a permit, we work to that edition.

What this means in an older house

The code does not require you to bring a whole older house up to today’s rules. Two things do trigger an update:

1. Replacing an outlet. When an outlet is replaced in a location that now requires GFCI or AFCI protection, the replacement has to have it.
2. New work. A new circuit, a remodel or an addition is wired to the current code.

Home inspectors check for GFCI protection in kitchens, bathrooms, garages and outdoors, and missing protection is one of the most common items on an inspection report. It is usually a quick fix: a GFCI outlet in the first position on the circuit, or a GFCI breaker in the panel.

When to call an electrician

Test each GFCI once a month: press TEST, the power should go off, then press RESET. Call a licensed electrician if:

• A GFCI or AFCI trips again as soon as you reset it, or trips often without an obvious cause. That points to a fault on the circuit, not a bad device.
• An outlet will not reset, or does not cut the power when you press TEST.
• You have outlets near water with no GFCI protection, or a home inspection report lists missing GFCI or AFCI protection.
• You want a hot tub, pool equipment or an outdoor kitchen wired. These need the right protection at the panel, and usually a permit.

Working inside an outlet box or a panel means working on live parts. In Rock Hill, the city requires electrical work in a home to be done by a licensed contractor. We install and replace GFCI and AFCI outlets and breakers across Rock Hill, Fort Mill, York County and Charlotte, and we give you the price before any work starts.