Thread: AFCI tripping when raining

I have a problem in my own house that started this past weekend. Our summer rains have finally started, and last Saturday, Monday, and today, during heavy blowing rainstorms the AFCI for the 2 guest bedrooms in my home (one AFCI circuit.) trip. I have lived here 18 months and did not have this issue last summer. After the second time, I did some investigation.
House built 2005, CBS construction. Typical 3 bed 2 bath. Main panel is in garage, 200 AMP Square D.

The inside of the panel is dry (there is a through roof mast, and I thought maybe water was running down through the roof jack.)

I got in the attic thinking maybe there was a leak, and water was running between the block wall, and drywall into receptacle. Attic has no leaks. I also pulled the covers off the receptacles inside both bedrooms, that are on exterior walls. All bone dry.

An hour or so after the rain stops the AFCI breaker will reset, it will even reset after it has tripped during light rain. The only time it trips is when there is heavy Florida rain.

Any ideas???????

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Could an exterior device (light fixture, switch, or receptacle) be on the AFCI circuit?

Good idea, although it should not be, who knows. I will check tomorrow.

Is there something about Florida rain that is different from the rain here in Kansas ... I just thought of a great excuse to tell a customer when he has problems with his afci's tripping .... dang the luck it must be that freakin Florida rain ....

I think James has most likely given you the best bet considering this only happens when it is raining.

Originally Posted by Roger Frazee

Is there something about Florida rain that is different from the rain here in Kansas ... I just thought of a great excuse to tell a customer when he has problems with his afci's tripping .... dang the luck it must be that freakin Florida rain ....

I think James has most likely given you the best bet considering this only happens when it is raining.

Yep there is a difference. It would be like comparing Kansas tornados to Florida tornados.

111111

James was correct. In the front bedroom an exterior receptacle directly opposite an interior receptacle was on the AFCI circuit. I haven't opened anything up yet, but will probably just do away with that exterior receptacle. So, is this acceptable practice? Is the AFCI circuit more sensitive to moisture?

Originally Posted by Paul Kondzich

So, is this acceptable practice?

The outdoor receptacle needs GFCI protection, does it not? You did not say whether that is the case. In my area, the usual practice is to run a dedicated circuit for all the outdoor receptacles. However, the others say this is common, indoor to outdoor, so yes it may well be usual practice down your way. BTW, outdoor lighting often comes from a switch inside the door, so yes, lighting is almost always indoor to outdoor.

Originally Posted by Paul Kondzich

Is the AFCI circuit more sensitive to moisture?

Yes, because it is detecting a path across the moisture to ground or to the neutral, in other words, a potential arc. Correction, an arc, not a potential arc. Thanks, Bill []
A plastic cover over the receptacle, a more weathproof unit, may solve the problem and you'll still have the outlet.

Originally Posted by John Kogel

Yes, because it is detecting a path across the moisture to ground or to the neutral, in other words, a potential arc.

Absolutey, positively, does NOT detect potential ARCs - only detects them when they happen.

Most AFCI devices have a GFI built in as part of the device, although it trips at 20 mA rather than the 5 mA a receptacle does. Your problem is the device is detecting either a ground fault or a neutral to ground current leak when something gets wet.

If there's more than one AFCI in the panel I'd swap circuits and see if the problem moves with the circuit or if it stays on the same device. I've replaced a bunch of AFCIs that seem to trip for no real apparent reason and suspect that condensation might be the culprit as the replacement never trips.

Thanks John. Here it's GFCI exterior, kitchen, bath, and laundry in this era. That's what I thought I had. Now that I think about it when I did the inspection here before I bought it, I think I wrote up that exterior receptacle not tripping (GFCI) but never thought any more about it. I guess I was asking if it's Ok to carry the AFCI circuit outside, when it was supposed to be a GFCI.

Originally Posted by Bill Kriegh

Absolutey, positively, does NOT detect potential ARCs - only detects them when they happen.

Most AFCI devices have a GFI built in as part of the device, although it trips at 20 mA rather than the 5 mA a receptacle does. Your problem is the device is detecting either a ground fault or a neutral to ground current leak when something gets wet.

If there's more than one AFCI in the panel I'd swap circuits and see if the problem moves with the circuit or if it stays on the same device. I've replaced a bunch of AFCIs that seem to trip for no real apparent reason and suspect that condensation might be the culprit as the replacement never trips.

I swapped 2 AFCI breakers yesterday. So far all is well, it has rained today, but not heavy driving rain. I'm going to open up the outside receptacle this weekend.

Originally Posted by Bill Kriegh

Absolutey, positively, does NOT detect potential ARCs - only detects them when they happen.

Most AFCI devices have a GFI built in as part of the device, although it trips at 20 mA rather than the 5 mA a receptacle does. Your problem is the device is detecting either a ground fault or a neutral to ground current leak when something gets wet.

If there's more than one AFCI in the panel I'd swap circuits and see if the problem moves with the circuit or if it stays on the same device. I've replaced a bunch of AFCIs that seem to trip for no real apparent reason and suspect that condensation might be the culprit as the replacement never trips.

Untrue/false.

More than one type of AFCI device - and more than one type of combination MCCB/AFCI.


GFPE is not GFCI

20 mA is not the threshold.

Baseless, useless, and inaccurate information.