Test every GFCI at least once a month, and again after a power outage (CPSC). Plug in a lamp and turn it on, press Test (the light should go off), then press Reset (the light should come back). If it won't trip, call an electrician. If it won't reset, it needs replacing.
CPSC notes that GFCIs can fail without any sign, so the monthly press is the only way to know. It fits neatly into the monthly round of safety checks. Our guide on how often to test smoke detectors has the full 10-minute monthly safety round, alarms included.
What a GFCI does
A ground fault circuit interrupter (GFCI or GFI) watches the current going out and coming back on a circuit. If the two differ by as little as 0.006 amps, which means current is leaking somewhere it shouldn't, such as through a person, it cuts the power in a fraction of a second (CPSC). That's fast enough to help prevent a deadly shock. The Electrical Safety Foundation International (ESFI) says GFCIs have helped cut home electrocutions in half since the 1970s.
There are three kinds (CPSC):
- GFCI outlets with Test and Reset buttons. They protect anything plugged into them, and other outlets wired after them on the same circuit.
- GFCI circuit breakers in the panel, which protect the whole circuit.
- Portable GFCIs that plug into a regular outlet, handy for power tools and garden equipment.
Where you'll find them
GFCIs go where water and electricity meet. The National Electrical Code added them over the years (CPSC):
- Outdoor outlets (1973)
- Bathrooms (1975)
- Garages (1978)
- Kitchens (1987)
- Crawl spaces and unfinished basements (1990)
- Wet bar sinks (1993)
- Laundry and utility sinks (2005)
The code applies to new building and major remodels, so an older home may not have GFCIs everywhere a new one would. If an outlet in one of these spots has no Test button, it may be protected by a GFCI outlet elsewhere on the circuit or by a GFCI breaker, or it may not be protected at all. An electrician can tell you.
How to test a GFCI outlet (the lamp method)
Follow your GFCI's instructions if you have them. If not, CPSC's method:
- Plug a lamp into the GFCI outlet and turn it on. A nightlight works too (ESFI).
- Press Test. The lamp should go off.
- While it's tripped, plug the lamp into the other outlets nearby. Any that are also dead are protected by this GFCI. Note them for next time.
- Press Reset. The lamp should come back on.
- Write down the date and the result.
For a GFCI breaker, CPSC says to press its Test button: the handle should move to the middle or off position. To reset it, move the handle to off, then back on.
If it won't trip or won't reset
- Lamp stays on after you press Test: the GFCI isn't working or was wired wrong. CPSC says to have an electrician fix the wiring or replace it. Until then, treat that outlet as unprotected.
- Lamp won't come back on after Reset: CPSC says to replace the GFCI. First check that the breaker hasn't tripped.
ESFI recommends that a licensed electrician install GFCIs. If you're not comfortable working with wiring, this is a job to hand over.
Self-testing GFCIs still need a press
Since June 29, 2015, GFCI outlets and breakers made to the UL standard have had to include a self-test feature, and most cut the power if they find a problem (UL, writing in IAEI Magazine). Self-test can't check every part, though, so UL says the Test button should still be used regularly. Keep testing monthly whatever the age of the outlet.
Plug-in tester or the Test button?
Use the GFCI's own Test button. That's the method CPSC and ESFI describe, and it checks that the device itself trips. Plug-in outlet testers are useful for other checks, but follow the tester's own instructions and don't use one in place of the monthly button test.
When to call an electrician
- A GFCI won't trip when you press Test.
- It trips again straight after a reset with nothing plugged in.
- An outlet or switch feels warm. CPSC says to stop using it until an electrician checks it, as it can mean a loose connection or unsafe wiring.
- A kitchen, bathroom, garage or outdoor outlet has no GFCI protection that you can find.
GFCI test log (printable)
| Location | Date | Trips on Test? | Resets? | Pass or fail |
|---|---|---|---|---|
| Kitchen counter | ||||
| Bathroom 1 | ||||
| Bathroom 2 | ||||
| Laundry or utility sink | ||||
| Garage | ||||
| Unfinished basement or crawl space | ||||
| Outdoor, front | ||||
| Outdoor, back |
Landlords: a dated log like this is worth keeping for each unit. Test GFCIs between tenants as part of your rental turnover checklist.
Questions people ask
How often should a GFCI be tested?
At least once a month, after it's installed, after a power outage and whenever the manufacturer says (CPSC).
What if my GFCI won't reset?
CPSC says to replace a GFCI that won't reset. Check first that the power is on at the breaker; if it still won't reset, call an electrician.
Do GFCIs wear out?
They can. CPSC notes that blackouts and power surges can damage them, which is why a monthly test matters. Newer self-testing GFCIs check some parts on their own, but UL says you should still press Test regularly.
Why does my GFCI keep tripping?
It trips when it senses current leaking from a circuit, often from a damaged appliance or water getting into something (ESFI). Unplug everything and reset it; if it trips again with nothing plugged in, call an electrician.
Is an outlet downstream of a GFCI protected?
It can be. CPSC says a GFCI outlet also protects the outlets wired after it on the same circuit. Press Test and plug a lamp into the other outlets nearby: any that go dead are protected by that GFCI.
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Sources
- CPSC: What is a GFCI? (fact sheet, PDF)
- Electrical Safety Foundation International: Ground fault circuit interrupters
- CPSC: Home electrical safety checklist (PDF)
- IAEI Magazine, UL Question Corner: Self-testing GFCI requirements
General guidance only. Follow your manufacturer's instructions, and call a licensed professional for gas, electrical, roofing or anything that feels unsafe.