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# GFCI vs AFCI: What Each One Protects You From

Two devices with similar names that do completely different jobs. Where California requires each, why they nuisance trip, and what to do when they won't reset.

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Safety | Updated 2026-03-10 | Rupert Electrical Solutions

GFCI and AFCI sound like variations on the same idea. They are not. One protects people, the other protects the building, and confusing them is why some homeowners install the wrong device and wonder why it keeps tripping.

## GFCI: protects people from shock

A ground fault circuit interrupter compares current leaving on the hot conductor with current returning on the neutral. If they differ by a tiny amount, roughly 5 milliamps, some current is going somewhere else. Often that somewhere else is a person. It opens the circuit in a fraction of a second, fast enough to prevent an electrocution.

That is why GFCI lives in wet locations: kitchens, bathrooms, laundry, garages, unfinished basements, crawlspaces, outdoors, and near pools and hot tubs. Water lowers your body's resistance and creates the leakage path.

## AFCI: protects the building from fire

An arc fault circuit interrupter watches the electrical signature of the current for the chaotic, irregular pattern that arcing produces. Arcing across a loose terminal or through damaged insulation makes very high localized temperatures without necessarily drawing enough total current to trip a conventional breaker. It can smoulder in a wall cavity for a long time.

AFCI protection is required for most living-area circuits: bedrooms, living rooms, dining rooms, hallways, closets, kitchens and laundry. It exists because a standard breaker cannot see this fault at all.

## A quick reference

| GFCI | AFCI
--- | --- | ---
Protects | People from electric shock | Structure from electrical fire
Detects | Current leaking out of the circuit | The signature of arcing
Where required | Wet and outdoor locations | Living-area circuits
Common form | Outlet or breaker | Breaker, sometimes outlet

Dual-function devices provide both, and are common on kitchen and laundry circuits where both requirements apply.

## Why they nuisance trip

GFCI trips are usually real. Moisture in an outdoor box after rain, a failing water heater element, an old motor with degraded insulation, or a long circuit accumulating enough capacitive leakage to cross the threshold. Before assuming the device is faulty, unplug everything on the circuit and reset.

AFCI trips are more often blamed on the breaker than they deserve. Some genuine causes: a loose back-stabbed receptacle connection arcing under load, a damaged cable, a shared neutral between two circuits, or a vacuum motor whose brush noise mimics an arc. The last one is a real limitation of the technology. The first two are exactly what it is for.

## When a GFCI won't reset

1. Check that you are pressing the right one. A single GFCI can protect a whole run of downstream outlets, and the device is often in another room.
2. Unplug everything on the circuit, then reset. If it holds, add loads back one at a time.
3. Look for water. Sprinklers hitting an exterior receptacle is a classic.
4. Check the breaker too. Both have to be on.
5. If it still won't hold with nothing connected, either the device has failed or there is real leakage in the wiring. That is a service call.

One thing to avoid: replacing a tripping GFCI with a standard outlet to make the problem go away. It doesn't remove the fault, it removes the protection, and it is what we find behind a surprising number of "the old one was broken" calls.

## Testing, which almost nobody does

Press the TEST button on every GFCI and AFCI in the house monthly. It should trip immediately and reset cleanly. Devices do fail, and they fail silently, so a device that has sat untested for fifteen years may offer no protection at all while looking perfectly normal.

If you have no GFCI protection in wet locations, that is one of the cheapest and highest-value electrical upgrades available. Rupert Electrical Solutions adds it during any outlet & switch installation visit.

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