From October to April a particular call comes in every week: the tub was fine all summer, now the GFCI trips the first wet night and holds the next dry morning. Owners assume the pack has failed. It almost never has. Rain is finding a connection, and current is leaking to ground through water.
The four places water gets in
The cord-end GFCI on a 120 V plug-and-play tub. It lives outdoors, usually a foot off the deck, and the cord drips straight into it. Townhome and roof-deck tubs in Ballard, Fremont and Capitol Hill trip here more than anywhere else. A covered in-use outlet box and a drip loop in the cord solves most of it.
The spa disconnect box. Older boxes on older Seattle houses lose their gasket; a conduit that enters from the top channels water inside. The symptom is a trip during the storm, not after it.
The pack's terminal strip. If the equipment door does not seal — common when a tub has been moved or the cabinet has settled on a terraced lot — spray reaches the pack. The trip comes with a damp smell when the door is opened.
The heater element. This one is not rain at all, but rain makes it worse: an element already etched thin by soft water leaks a little current to ground at all times, and a wet, cold night pushes it over the GFCI's threshold.
What to do before calling
Do not keep resetting it, and never replace it with a standard breaker. Note whether the trip is instant or after a few minutes of heating: instant points at a wet connection or a shorted pump, delayed points at the heater. If the tub is plug-and-play, look at the cord GFCI and the outlet — if either is wet, you have found it.
What the visit looks like
We isolate the loads one at a time — heater, pumps, blower, ozonator, light — and measure which one leaks. Wet connections get dried, sealed and re-routed; an etched element gets replaced with calcium added to the refill so the next one lasts. New circuits and panel work are a licensed electrician's job in Seattle and need a permit; everything from the disconnect to the tub is ours.
Questions
Is a GFCI that trips in the rain dangerous?
Can I just replace the GFCI breaker?
Related services
Next note: What to do with a hot tub when a Seattle windstorm takes the power out