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I have a single 15A 1P breaker that trips every time it rains. This is a relatively new problem since I upgraded the main panel in my house from a very old one (that never had any breakers trip). House was built in 1961.

I was uncertain that it was necessarily the rain, but the pattern is unmistakable at this point. The breaker will stay on and work fine, then about 12 hrs after it starts raining it will trip. If I try to flip it back on in that time, it will immediately trip again. Once the rain has stopped for a few days I can turn the breaker back on again and it will stay on.

The breaker only supplies power to a few lights and the igniter/lights/fan for a gas range. The roof of the house is in poor condition and will be replaced soon, but I'd like to fix this wiring issue regardless.

Any tips on how I can diagnose exactly where this wiring issue is? I unfortunately don't have attic access to this section of the house and I'd prefer not to cut into drywall unless I know where to cut.

Edit: I found it! Few photos below - at some point, it looks like somebody knocked an exterior receptacle off the wall and when they tightened it back down, they pinched the hot wire against the metal box. I suspect the rain gave it a better path to ground, which caused the breaker to trip.

This receptacle wasn't accessible until recently (we have been having a high deck replaced so there has been no way to get to it) but I will note that I had three electricians look at this and all three just installed a new breaker...

Fire

Crimped wiring

Damaged box

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    Is this a simple breaker or a GFCI or AFCI? GFCI is required (either at breaker or receptacle) for newer outdoor receptacles, kitchen receptacles, etc. Not clear actually - are any receptacles, lights, etc. on this circuit outside? If so, that's the likely source of the problem. If not then that sounds like the roof...
    – manassehkatz-Moving 2 Codidact
    Mar 3 at 2:11
  • No, normal breaker. It should be GFCI but the electrician replaced the gfci with a normal breaker after the gfci tripped too many times….
    – topher
    Mar 3 at 2:45
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    So now a regular breaker trips 12 hours after rain? That's scary.
    – manassehkatz-Moving 2 Codidact
    Mar 3 at 2:51
  • Is the new panel inside or outside
    – asinine
    Mar 3 at 5:11
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    The electrician replaced a GFCI breaker with a regular one because the GFCI was tripping? Unless it's for a fridge (which are usually excluded from GFCI rules), that sounds very much the wrong way to go about solving the problem. How about looking for an actual ground fault??!?!!!?!
    – FreeMan
    Mar 3 at 16:56

3 Answers 3

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Any tips on how I can diagnose exactly where this wiring issue is?

Perhaps water is seeping into an electrical outlet/junction box or the panel.

Open the main panel and the boxes of all outlets / switches on the circuit to see if any is wet during rain.

The easiest water short I can think of, for instance, is water between the live side screw of a receptacle and the grounded metal side of its housing. That space can be a mere 1/16in, or even less if the alternate screw is not tightened.

Also, any dirt like drywall mud/filler, dust, spider or wasp nests, or aged grime accumulated in a box can be an isolator when dry and a conductor when wet.

If all boxes turn up clean and dry, next is the cabling: "dry location" NMD cable that has been exposed to water for long periods of time, for instance in wet ground or in water filled conduit, will have deteriorated and could also cause a short to ground.

Your initial symptom of a tripping GFCI hints at a live to ground short, which with sufficient water is now so bad that it trips a normal breaker. This is a fire hazard, and you are lucky the breaker is tripping.

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  • "Your initial symptom of a tripping GFCI hints at a live to ground short, which with sufficient water is now so bad that it trips a normal breaker. This is a fire hazard, and you are lucky the breaker is tripping." +100!!
    – FreeMan
    Mar 3 at 16:57
  • Edited my original question with my findings - opening all the outlets helped me find this.
    – topher
    May 11 at 22:29
  • @topher nice! congrats on finding this, and thank you for posting your findings, which is great feedback for all readers
    – P2000
    May 13 at 14:10
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"The breaker only supplies power to a few lights and the igniter/lights/fan for a gas range."

If you mean exhaust fan, I would suspect water coming down the fan vent (inside or outside the pipe) and shorting something out in the range hood.

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It sounds like your roof repair can no longer wait.

Replacing the old panel with new one opened the path for water to make the breaker trip.

Easy check for any humidity inside the panel.

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