Before opening the GFCI device, establish an electrically safe work condition.

With the breaker ON and the GFCI in place, do you have line-side voltage at the device? (You can confirm without opening it by checking the upstream breaker is on and not tripped.)

Unplug everything downstream of this GFCI (including any other receptacles it protects) and try to reset.

GFCIs protect themselves AND any downstream outlets wired to LOAD. A fault on a downstream device looks identical to one at the GFCI itself.

How old is the GFCI device? (Estimate is fine.)

UL 943 has required self-test and end-of-life lockout since ~2015. A modern GFCI that won't reset is most commonly at end of life.

If this device was recently installed, check that the supply (incoming hot/neutral) is on the LINE terminals, not LOAD. Modern GFCIs miswire-lockout if reversed.

electrical troubleshooting

GFCI won't reset

Common symptoms: gfci won't reset; gfci tripped; gfci dead; outlet not working; gfci button won't stay in

Stop and call a pro if:

lockout-tagout-required

Step-by-step diagnostic flow

Step 1
Before opening the GFCI device, establish an electrically safe work condition.
Step 2
With the breaker ON and the GFCI in place, do you have line-side voltage at the device? (You can confirm without opening it by checking the upstream breaker is on and not tripped.)
Step 3
Unplug everything downstream of this GFCI (including any other receptacles it protects) and try to reset.
GFCIs protect themselves AND any downstream outlets wired to LOAD. A fault on a downstream device looks identical to one at the GFCI itself.
Step 4
How old is the GFCI device? (Estimate is fine.)
UL 943 has required self-test and end-of-life lockout since ~2015. A modern GFCI that won't reset is most commonly at end of life.
Step 5
If this device was recently installed, check that the supply (incoming hot/neutral) is on the LINE terminals, not LOAD. Modern GFCIs miswire-lockout if reversed.

Possible outcomes

Stop — establish electrically safe condition first

high confidence

NFPA 70E §120.5 — verify zero energy before opening the device.

Safe next steps

Turn off the breaker and verify with a known-good tester before pulling the GFCI

Upstream breaker is tripped

high confidence

The GFCI cannot reset without line-side power.

Safe next steps

Reset the upstream breaker
If the breaker won't reset either, see 'Breaker keeps tripping' workflow

Likely a ground fault on a downstream device

high confidence

The GFCI resets with downstream loads disconnected, so the fault is on something it protects.

Safe next steps

Plug devices back in one at a time until the GFCI trips again — the last device added is the source
Replace or repair that device

What to document for a pro

Which device caused the trip
Whether it's wet, damaged, or older

GFCI is likely at end of life — replace the device

high confidence

UL 943 self-test GFCIs enter an auto-monitoring lockout when the sensing circuit fails — refusing to reset even on a known-good circuit. Service life is typically 10–15 years.

Safe next steps

With the breaker off and verified de-energized, replace the GFCI with a current UL 943 self-test device
Match LINE/LOAD terminals to the wires you removed

What to document for a pro

GFCI brand and date code if visible
Whether other GFCIs in the home are the same vintage (likely all near end of life)

Likely miswire — LINE and LOAD terminals reversed at installation

high confidence

Modern GFCIs miswire-lockout if supply is landed on LOAD instead of LINE.

Safe next steps

De-energize and verify zero energy
Identify the incoming supply cable (use a non-contact tester with breaker on, then de-energize again before working)
Land supply on LINE; downstream devices on LOAD

What to document for a pro

Photos of existing wiring before re-landing

Diagnostic guidance only. If unsure, stop and call a licensed professional — gas, electrical, and refrigerant work is hazardous to untrained users.

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