Key takeaways
- A GFCI guards against shock by shutting off power when current leaks out of the circuit.
- An AFCI guards against fire by detecting arcing in damaged or loose wiring and cords.
- Modern code requires both in many areas of the home, and the list has grown over time.
- Test buttons are safe for homeowners to use. Replacing or troubleshooting devices is not.
What a GFCI does
A ground-fault circuit interrupter, or GFCI, compares the current going out on the hot wire with the current coming back on the neutral. In a healthy circuit they are equal. If some of that current is going somewhere else, such as through a person touching a live part while standing on a wet floor, the GFCI notices the difference and cuts power in a fraction of a second.
The threshold is only a few thousandths of an amp, far less than what an ordinary breaker would ever notice. That is the point. A regular breaker protects the wire from overheating. A GFCI protects you from shock.
GFCI protection can come from a GFCI outlet, which has test and reset buttons on its face, or from a GFCI breaker in the panel. One GFCI outlet can also protect other standard outlets downstream on the same circuit, which is why a dead outlet in a garage or bathroom is sometimes fixed by resetting a GFCI somewhere else.
GFCI protection matters most near water, which is why you see it in bathrooms, kitchens, basements, garages, and outdoors. In a damp basement, a common feature of homes in this region, it earns its place.
What an AFCI does
An arc-fault circuit interrupter, or AFCI, looks for the electrical pattern of an arc. Arcing happens when electricity jumps across a gap, such as a damaged cord pinched behind furniture, a nail through a cable, or a loose connection at an outlet. The heat from an arc can ignite surrounding material, often before a standard breaker sees any problem.
An AFCI breaker listens for those patterns and trips when it detects a dangerous one, while ignoring harmless arcs such as the small spark when you unplug something. It is a different safeguard from a GFCI and responds to a different hazard.
In older homes, AFCI protection is especially relevant. Aging insulation, past repairs, and wiring that has been disturbed by renovations are all places where arcing can develop out of sight. AFCI protection does not repair any of those problems, but it can warn you by tripping.
Many modern breakers combine both functions and are marketed as dual-function devices. Ask an electrician which type suits a given circuit.
Where protection is generally required
Electrical codes are updated every few years, and each update has tended to widen the list of places that need protection. As a general guide, current code calls for GFCI protection in areas such as:
- bathrooms
- kitchens, at least near sinks and countertops
- garages and unfinished basements
- crawl spaces
- laundry areas and near utility sinks
- outdoor outlets
AFCI protection is now required for most living areas in new construction and major renovations, including bedrooms, living rooms, dining rooms, and hallways. It began with bedrooms and has expanded.
What applies to your home depends on when it was built, what work is being done, and which code edition your local jurisdiction has adopted. Existing homes are generally not required to add protection retroactively, but when you replace a panel, add circuits, or do major remodeling, newer requirements may apply. Your local building department sets the rules, and an electrician working in your area will know what applies.
Even where it is not required, adding protection to an older house is among the more worthwhile safety improvements. Wiring work is often a good time to plan it.
How to test your devices
GFCI outlets and breakers have a test button and a reset button. Manufacturers generally recommend testing them about once a month. It takes a minute:
- Press the test button. The device should trip and power to it, and anything downstream, should go off.
- Press the reset button. Power should return.
If the device does not trip, does not reset, or feels hot, stop using that circuit and call an electrician. A GFCI that has stopped working is no longer protecting you, even if the outlet still delivers power.
AFCI breakers also have a test button. Pressing it should trip the breaker, and you reset it by switching it fully off and then back on. If you are not sure which breakers in your panel are AFCI, look for the test button and the labeling on the breaker, but do not remove the panel cover to do it. Many panels have a door that you can open without exposing live parts. If you cannot tell, an electrician can identify them.
Testing by pressing a button is safe. Taking devices apart or replacing them is not something to do on your own, because it means working on live circuits or inside the panel.
When a device keeps tripping
A GFCI or AFCI that trips once after a storm, a wet day, or a damaged cord may simply be doing its job. One that trips repeatedly deserves attention.
Common causes include moisture in an outdoor outlet or a basement, a failing appliance or extension cord, a wiring fault, or a worn device. Older AFCI breakers can also trip when paired with certain equipment. A good electrician will trace the circuit rather than just replacing the device, because the device is often telling you something real.
Avoid the temptation to bypass the protection or swap in a standard outlet or breaker because it is annoying. That removes the safeguard exactly where it was needed.
If you want protection added to older circuits, or you have a device that trips and you cannot find the reason, electrical repair is the right place to start, and you can contact us with the details.
Frequently asked questions
Can I replace a regular outlet with a GFCI outlet myself?
That involves working on wiring, and mistakes in connecting line and load wires can leave the outlet looking protected when it is not. We recommend having an electrician do it, especially in older homes where the wiring may be ungrounded or in uncertain condition.
Why does my GFCI trip when it rains?
Moisture getting into an outdoor outlet, a weatherproof cover that is damaged, or a wet extension cord connection can cause leakage that the GFCI detects. If it keeps happening, have an electrician check the outlet and the wiring behind it.
Do older homes need AFCI protection?
Existing homes are generally not required to add it unless work triggers the newer rules, but it can be added to many circuits. An electrician can tell you which circuits in your panel can accept AFCI breakers.
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