GFCI stands for ground-fault circuit interrupter. The outlet compares the current going out on the hot wire with the current coming back on the neutral. If they differ by as little as 5 milliamps, it assumes some of that current is going somewhere it should not and shuts off.
That speed is the point. A shock that would be dangerous at a normal outlet is cut off before it can do serious harm.
Where your home needs them
Electrical codes have added locations with almost every edition, so an older home may not have them everywhere newer homes do. Recent editions of the National Electrical Code call for GFCI protection in places including:
- Bathrooms
- All kitchen outlets, not just the countertops
- Laundry areas and within 6 feet of any sink
- Garages and accessory buildings
- Basements, finished or not
- Crawlspaces
- All outdoor outlets
- Outlets near pools, hot tubs and wet bars
Which edition applies depends on your city or county, and existing homes are not usually required to upgrade until the wiring is changed. It is still worth adding protection in these places.
One GFCI can protect the regular outlets wired after it on the same circuit. Those downstream outlets should carry a small “GFCI Protected” sticker. Often they do not, which is why people hunt for the wrong reset button.
Resetting one that has tripped
Unplug what was running
Whatever was plugged in when it tripped may be the cause. Unplug it before resetting.
Find the GFCI
Check the outlet itself, then other bathrooms, the garage, the basement and exterior outlets on the same side of the house. One GFCI in a garage can protect an outdoor outlet and a bathroom.
Press RESET firmly
You should feel a click. If it will not stay in, the circuit may have no power. Check the breaker panel for a tripped breaker.
Plug things back in one at a time
If it trips again as you plug in one item, that appliance probably has a fault.
Testing it every month
Press TEST. The RESET button should pop out and the outlet should go dead. Plug in a lamp or a phone charger to confirm. Then press RESET to restore power. Manufacturers recommend doing this monthly; doing it twice a year is far better than never.
If you press TEST and nothing happens, or the outlet still has power, the GFCI is no longer protecting anyone and should be replaced.
Signs it is worn out
- It trips with nothing plugged in
- It will not reset, even with power at the breaker
- TEST does not cut the power
- It is more than ten years old and trips often
- It feels warm, buzzes, or shows scorch marks
Replacing a GFCI
Replacing a GFCI is a common DIY job for people who have wired outlets before. The catch is the LINE and LOAD terminals. Wire the incoming power to LOAD by mistake and the outlet may seem to work while protecting nothing. If you have not done it before, this is a good one to watch someone do first.
Common questions
Is a GFCI the same as an AFCI?
No. A GFCI protects people from shock. An AFCI detects arcing in wiring that can start fires. Newer homes have AFCI protection on most bedroom and living-area circuits, often built into the breaker.
Can I put a refrigerator on a GFCI?
Code requires it in many kitchens and garages now. Modern GFCIs rarely nuisance-trip with a healthy fridge. If one keeps tripping, have the fridge and outlet checked.
Our guides are general information for typical homes. Codes, permits and conditions vary, so check local rules, and leave gas, main electrical panel and structural work to a licensed professional.
