Troubleshooting guide

Why Does a GFCI Keep Tripping?

Ground-fault current, moisture, shared neutrals, damaged appliances and nuisance trips: how to tell the causes apart.

Electrical & Power · Last reviewed October 15, 2026

A GFCI compares the current going out on the hot conductor with the current returning on the neutral. If they differ by about 4 to 6 mA or more, some current is leaving the circuit by another path, possibly through a person, and the device opens in a fraction of a second.

A GFCI that trips is doing its job. Do not bypass or replace it with a non-GFCI device to stop the trips. Troubleshooting energized circuits belongs with a qualified electrician.

Pattern	Likely cause	What to check
Trips with one particular appliance	Leakage current in the appliance (heating element, damaged cord, wet motor)	Unplug and test the appliance on another GFCI. Look for a damaged cord or moisture
Trips after rain or when damp	Water in an outdoor box, fixture or cable	Weatherproof covers, damaged cable, sealed fittings
Trips right after reset with nothing plugged in	Wiring fault: neutral touching ground, or a damaged conductor	The load side wiring with power off. A qualified electrician can test insulation
Trips when another circuit is loaded	Shared neutral between circuits, or a neutral connected to the wrong place	Check that each GFCI circuit has its own neutral and that no neutrals are shared or crossed between circuits
Trips at random, no pattern	Many small leakage currents adding up, long cable runs, or a worn device	Number of loads and cable length on the circuit. Replace an old GFCI that fails its test button
Will not reset	Line and load wires swapped, internal fault, or a persistent ground fault	Wiring at the device terminals, device condition

A sum-of-leakage example

Electronic equipment, such as a computer power supply, passes a small leakage current to ground by design, often a fraction of a milliampere. Ten such loads of 0.5 mA each leak 5 mA together, which is at the trip threshold of a Class A GFCI (4 to 6 mA). None of the loads is faulty, but together they trip the device. Splitting them across circuits fixes it.

Write a useful problem statement

Device type, location (indoor, outdoor, damp) and the circuit it protects.
What was connected when it tripped, and how soon after the reset.
Weather or moisture at the time.
Test button result and the age of the device.

GFCI, AFCI and breakers compared

Device	What it detects	What it protects against
GFCI	Current leaving the circuit by a path other than the neutral (about 4 to 6 mA or more)	Electric shock
AFCI	The electrical signature of an arc in the wiring or in a cord	Fire caused by arcing
Standard breaker	Overload and short-circuit current	Overheated wiring and equipment

Preventive checks

Press the test button on each GFCI on a regular schedule and reset it afterward.
Replace a GFCI that fails the test, or that has been in service for many years.
Keep outdoor and damp-location boxes sealed, with weatherproof covers that close.
Do not run several large appliances with heating elements from one GFCI circuit.

Related tools and labs

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Questions

How often should a GFCI be tested?

Manufacturers commonly recommend monthly use of the test button. Follow the instructions on the device.

Is a GFCI the same as an AFCI?

No. A GFCI detects current leaking to ground to protect people from shock. An AFCI detects arcing to help prevent fires.

Why does a GFCI trip outdoors when it rains?

Moisture in a box, a fixture or a cord gives the current a path to ground. Sealing the box and drying or replacing the damaged part fixes it.

Can a GFCI protect against overload?

No. A GFCI detects leakage. The breaker on the circuit protects against overload and short circuits.

Can I add a GFCI to an old two-wire circuit?

In many jurisdictions a GFCI is allowed on a circuit without a ground wire, with labeling that says there is no equipment ground. Check the local code and use a qualified electrician.

Educational material. Examples use simplified, hypothetical inputs and are not a design, a construction document or professional engineering advice. Confirm requirements with the codes and standards adopted where the work is built and with a licensed engineer.

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