How to check a GFCI outlet
Press TEST, watch the power cut, press RESET, and repeat once a month.
To check a GFCI outlet, press the TEST button. The power should cut and the RESET button should pop out. Press RESET and the power comes back. UL, the safety testing lab, recommends running that test once a month, and a lamp or a plug-in tester checks outlets further down the same circuit.
The monthly test, step by step
You need a lamp or night light that works, and the outlet needs power. A GFCI that has no power can’t be tested.
- Press RESET first, so the outlet starts in its normal state.
- Plug in the lamp and turn it on.
- Press TEST. The lamp should go off, and the RESET button usually pops out.
- Press RESET. The lamp should come back on.
UL’s own wording is that the lamp “should go off” when you press TEST, and then come back on when you press RESET. If it behaves that way, the outlet passed.
Two results mean the outlet failed:
- The lamp stays on after you press TEST. The outlet is not giving ground-fault protection.
- The lamp goes off but RESET won’t hold or won’t click in.
UL says both cases call for replacement by a qualified electrician. Replacing a GFCI means working inside the box on the circuit wiring, so hire a licensed electrician, who will know whether your town wants a permit for it. In the meantime, stop using that outlet for anything you’d worry about around water.
How often
UL recommends testing every GFCI monthly. The UL 943 standard also requires makers to include that instruction. UL adds that GFCIs in places with sustained heat above 90 degrees Fahrenheit and humidity above 93 percent should be tested more often.
Don’t use TEST and RESET as an on-off switch for whatever is plugged in. UL warns against that.
What a GFCI is checking for
A GFCI compares the current going out on the hot wire with the current coming back on the neutral. If the two differ by about 4 to 6 milliamps (mA), some of it is going somewhere it shouldn’t, such as through a person, and the device cuts power. UL 943 sets the upper limit at 6 mA, and a GFCI trips in about 25 milliseconds, roughly 1/40 of a second.
The TEST button creates a small imbalance on purpose. If the outlet trips, the sensing and the switching both work.
Newer outlets test themselves, but still test them
UL 943 changed in 2015 so that new GFCIs must test themselves and either shut off or show a warning when they can no longer protect. Outlets sold before that change don’t have this. If yours has an indicator light, it’s probably a self-test model.
A self-test does not replace your monthly check. Leviton’s own page says self-test units “should still be tested every month”. Leviton also says that a light that is red or off is a reason to run the manual test right away.
| Maker | Light on the outlet | What the maker says it means |
|---|---|---|
| Leviton | Green | Passed the self-test, working |
| Leviton | Red, beeping, or no light | A problem may exist, run the manual test |
| Leviton (two-light models) | Amber | Tripped or fault, press RESET fully |
| Legrand (Pass & Seymour), Eaton | Flashing red | Failed its self-test, have it replaced |
Models vary by year and by line, and some flash red briefly at power-on or after a reset. Check the label or the paper that came in the box before you act on a color. If a maker’s page isn’t clear for your model, press TEST and RESET and let the result decide.
Checking the other outlets on the circuit
One GFCI outlet often protects several ordinary-looking outlets downstream of it. The ordinary ones have no buttons. UL’s check for them: plug the lamp into that outlet, press TEST on the GFCI, and the lamp should go off. Then press RESET.
A plug-in GFCI tester does the same job from the outlet itself. It’s a small plug with three wiring lights and a test button, sold at hardware stores. Plug it into the outlet you want to check and press its button. If the protection reaches that outlet, the tester lights go out and the GFCI that feeds it trips. Press RESET on the GFCI afterward.
Two limits to know:
- If the tester button does nothing, the outlet may not be protected at all, or the GFCI may have a fault. Either one is worth an electrician’s visit.
- The GFCI’s own TEST button is the check that counts. The tester is a screening tool.
If the wiring lights show a problem pattern instead of the normal one, don’t open anything up. Note the pattern and call an electrician.
Why a GFCI won’t reset
Work through the outside causes first, because they cost nothing:
| What you see | Likely cause | What to do |
|---|---|---|
| RESET does nothing, no light | The outlet has no power | Check the breaker panel for a tripped or middle-position breaker, turn it fully off, then on |
| A group of outlets is dead | An upstream GFCI tripped | Check nearby bathrooms, kitchen, garage, basement, and outdoor outlets, and press RESET on each |
| Trips again right away | A fault on the circuit or a plugged-in appliance | Unplug everything on the circuit, then try RESET |
| TEST trips it but RESET won’t hold | The device may have worn out | Call an electrician |
If it still won’t reset with everything unplugged and the breaker on, UL’s advice is replacement by a qualified electrician, and HomeTips points to the device or the wiring behind it. Miswired line and load connections can also stop a GFCI from resetting. That is inside-the-box work, so call an electrician.
One note on age. UL and the industry say that a field study found a small but significant share of older GFCIs stopped working after several years, which is one reason UL 943 added end-of-life rules and, in 2015, self-testing. If your outlet is old and has no indicator light, test it monthly and have it replaced when it fails.
Why it keeps tripping
A GFCI that trips now and then is usually reacting to something real. Engineers who deal with nuisance trips list these causes:
- Moisture. Outdoor outlets, bathrooms, and kitchens near the sink see condensation or water on plug faces. A weatherproof cover helps outdoors.
- A leaky appliance. Appliances may leak a small amount of current to ground, and several of them on one GFCI add up. If it trips only when one thing is plugged in, test that appliance on another GFCI circuit.
- Long wire runs. Wire length adds capacitive leakage, and on a long circuit that leakage can reach the trip threshold. Moving the GFCI closer to the equipment it protects is the usual fix, and that is an electrician’s call.
- Wiring faults, including a GFCI that was wired wrong.
UL’s advice is that a GFCI that “trips repeatedly during normal use” should be replaced by a qualified electrician, after the appliance has been checked. If the tripping follows rain, dry the area and look for a damaged outdoor cover. If it follows one appliance, repair or replace the appliance.
A GFCI trips on a current imbalance, so breaker size has little to do with it. If your problem is a breaker that trips when the load is high, the breaker size calculator shows what that load draws against the breaker’s rating. It does not find a ground fault.
Where homes usually have GFCI protection
The National Electrical Code requires GFCI protection in specific places through section 210.8. In homes, that commonly means bathrooms, kitchens, garages, basements, crawlspaces, and outdoors, with newer editions adding more places. The list gets longer with newer code editions and your area may use an older or amended one. Check with your local inspector about which rules apply to your house.
Some of these are GFCI breakers in the panel rather than outlets. A GFCI breaker has its own TEST button on the breaker. Press it, expect the breaker to trip, then switch it back on. Panel work beyond that button belongs to an electrician.