GFCI vs AFCI Protection: What Each One Does and Where You Need It

GFCI and AFCI are two different kinds of protective devices. People often confuse them because the names are similar, both have TEST buttons, and both can be built into a breaker or an outlet. They protect against different hazards, and many homes need both.

This guide explains what each device does, where homes typically use them, what to do in older homes, why they trip, and how to test them. For installation or replacement, see our GFCI and AFCI protection service page.

What does a GFCI do?

A ground-fault circuit interrupter (GFCI) monitors the current flowing out on the hot conductor and returning on the neutral conductor. If the two differ by a small amount, some current is leaking to another path, such as through a person or into water. The GFCI turns off power quickly. The Electrical Safety Foundation International (ESFI) describes GFCIs as protection against electric shock.

A GFCI does not protect against overload or short circuits. The breaker does that. It also does not detect arcing inside wiring.

What does an AFCI do?

An arc-fault circuit interrupter (AFCI) detects hazardous arcing in the wiring and turns off power before the arc can start a fire. ESFI notes that arcing commonly comes from damaged, stressed, overheated or worn wiring, such as a nail or screw that has pierced a cable inside a wall. AFCIs are most often installed as breakers in the panel. Outlet-style AFCIs also exist, and they protect cords and devices plugged into them.

Where are GFCI and AFCI protection typically required?

The National Electrical Code (NEC) sets the requirements, and each state decides which edition to adopt and enforce. The Minnesota Department of Labor and Industry lists the 2026 NEC as adopted effective August 17, 2026, with the 2023 NEC applying to permits filed before that date. Local amendments and the date of the permit affect what an inspector requires.

In general, ESFI states that the NEC requires GFCI protection in kitchens, bathrooms, garages, basements, crawl spaces and outdoors. Those are areas where water or damp conditions raise the chance of shock. For AFCIs, ESFI notes that the NEC has included requirements since its 2005 edition, started with bedroom circuits, and expanded to other living areas in later editions. A current-code newly built home typically has AFCI protection in bedrooms and living areas.

Existing homes are generally not required to add protection until the work triggers it, such as replacing a receptacle, adding a circuit or replacing a panel. Adding it voluntarily is allowed and often recommended. An electrician can tell you what applies to your project and permit.

What are dual-function devices?

A dual-function device provides both AFCI and GFCI protection in one unit. Dual-function breakers are common for circuits that need both kinds of protection, such as a kitchen circuit that serves receptacles near sinks and the rest of the room. The device label states which protections it provides, and the TEST button checks both functions.

Which form to use, a breaker or a receptacle, depends on the panel type, the number of circuits and where you want the reset button. A GFCI receptacle can also protect other receptacles downstream when wired as feed-through protection. The electrician decides how to wire it, and each protected outlet should be labeled where the code or inspector requires.

What should I do about two-prong outlets in an older home?

Many Twin Cities houses built before the 1960s have two-prong outlets with no equipment ground. Do not replace a two-prong outlet with a three-prong outlet unless a ground is actually connected. Do not use a three-prong adapter to defeat the missing ground.

Common code-recognized options are to rewire the circuit with a grounding conductor, or to replace the outlet with a GFCI receptacle that is marked to show it has no equipment ground. The GFCI adds shock protection, but it does not create a ground. Surge protectors and some electronics rely on a ground to work as designed, so they may not work as intended on an ungrounded circuit.

Upgrading the older wiring may also involve receptacles, switches and devices and a review of how the home is grounded and bonded. If you are not sure what is in your walls, have an electrician evaluate the circuit before you change an outlet.

Why does a GFCI or AFCI keep tripping?

A trip means the device detected a condition it is designed to stop. Some trips are caused by real faults, and some are nuisance trips. Common causes include:

• Moisture in an outdoor outlet, a bathroom fan or a basement circuit.
• A damaged cord or an appliance with worn insulation, such as a hair dryer, space heater or freezer.
• Loose connections or damaged wire inside a box, which can create arcing.
• Wiring errors such as a neutral shared between circuits or a neutral touching the ground, which can cause an AFCI or GFCI to trip when a load turns on.
• Some motors, tools and dimmers, which can resemble arcing to an AFCI.
• Long circuits or many plugged-in devices, which can add small leakage currents that together reach the GFCI limit.
• A worn device that has reached the end of its service life.

Unplug everything on the circuit, reset the device once, then plug items back in one at a time. If one item causes the trip, stop using it. If the device trips with nothing plugged in, will not reset, or feels warm, stop and call a licensed electrician for troubleshooting and repairs. Repeated resetting can leave an actual fault in place.

How do I test GFCI and AFCI protection?

ESFI recommends testing GFCIs every month. To test a GFCI outlet, press RESET, plug in a nightlight and confirm it is on. Press TEST, and the light should turn off. Press RESET, and the light should turn on again. If the light stays on after you press TEST, the GFCI is not working properly and should be replaced by an electrician.

ESFI also recommends pressing the TEST button on an AFCI once a month, and it advises using the built-in TEST button instead of store-bought testers, which may not work with every brand or type. A breaker that does not trip when tested should be replaced. Pressing TEST on a breaker turns off the circuit, so save any work on connected computers first.

Next steps

1. Test every GFCI and AFCI in your home this week and write down the date.
2. Make a list of outlets in kitchens, bathrooms, garages, basements and outdoors, and note which ones are not GFCI protected.
3. Note any two-prong outlets and any circuits that trip repeatedly.
4. Ask an electrician to add or correct protection where it is missing, or to fix wiring that causes nuisance trips. If an inspection or home sale has flagged problems, see electrical code corrections.

Prime Time Electric MN, LLC (License #EA807704) installs and replaces GFCI and AFCI protection in Twin Cities homes. To schedule an evaluation, request a quote or call 612-445-2794.