GFCI Keeps Tripping? Here's Why
Bathroom GFCIs fail and misbehave more often than any other location in the home, largely from years of accumulated steam and humidity exposure.
Work through the causes in order
Start by unplugging everything on the circuit and resetting the outlet. If it holds with nothing plugged in, reintroduce devices one at a time — the one that makes it trip again is your likely culprit, often a space heater, aquarium pump, or holiday lights with degraded insulation.
If it trips instantly with nothing plugged in at all, suspect either moisture inside the box (common outdoors or in humid bathrooms) or an aging GFCI whose internal sensor has drifted out of tolerance.
If the trips are new and coincide with installing a variable-speed HVAC unit, pool pump, or EVSE charger, high-frequency leakage current — not a true fault — may be the cause; this is exactly the scenario the newer 'GFCI-HF' device class was built to solve.
When to stop troubleshooting and call a licensed electrician
Any of the following warrants a professional rather than more DIY testing: the breaker trips along with the GFCI, the outlet feels warm or discolored, you smell anything burnt, the home has aluminum wiring or is on a shared/multi-wire neutral circuit, or the trips started after storm damage or flooding.