Our GFCI breaker will trip during heavy rain. It really needs
to be a VERY heavy rain of decent duration - just like the
thunderstorms we have been getting recently. I need to find
the location of the fault so that I can resolve this problem.
The breaker cannot be reset until everything has dried up
well enough (several hours to several days if more thunder
storms come through).
We have both bathrooms, two outdoor outlets and garage outlets
and door opener on the circuit. It gets annoying to have
no bathroom lights for several days.
Unfortunately, on visual inspection, the obvious culprits,
the external outlets (both located under eaves, with nothing
plugged into them, and with protective metal covers) seem dry
as dry. Everything else seems fine as well. So either the
problem is very subtle (which seems odd since the it is only
caused by ver unsubtle conditions), or maybe there is some
other outlet on the circuit that I am not aware of the
Is there any way to track down the source of the fault or
at least rule out particular locations without a lot of
hassle? If there's no easy way, what is the best way to
go about finding the source of the problem?
Thanks very much.
Locate an AC current leakage either to safety ground wire or
via some wire (inside wall or in appliance) to earth. The
current leakage is something greater than 150 microamps.
That's right - micro. All appliances have some leakage. So
when the GFCI trips, the leakage in microamp range increases
to the milliamp range. Find the microamp leakage and you may
find the milliamp leakage. Should current leakage be in upper
microamp range when GFCI does not trip, then suspect a 'usual'
Obvious and not waste time: you require both good eyes (the
visual inspection) and something that provides numbers
(ubiquitous 3.5 digit multimeter that can measure low, AC
current). A neutral wire (after GFCI) too close to a safety
ground wire can leak current in damp weather.
Generally something that trips during rain would also be
leaking 'less but too much' current during the 'dry season'.
There is more to this. But the point is to ask whether you
are ready to attack to the problem - or hire someone else. If
you do it, then it will take much longer. But you will
learn. The 'hired gun' costs less because he solves it
faster. However then you have learned nothing. Your choice.
Jonathan Joseph wrote:
I am comfortable enough with my knowledge of electricity and
wiring to do things like replace swithces, replace wiring that
had been chewed through by mice, and add an outlet in the middle
or end of a run. I am also comfortable using a multi-meter.
Unfortunately, I am not knowledgeable enough to follow your
instructions for finding a current leakage. Thank you for
responding though. I hope some of the simpler suggestions
prove fruitful for finding the source of the problem. If I
can find it, I think I can probably fix it.
Instructions were never posted for finding current
leakage. I don't know how anyone could have followed them.
Summarized (without any necessary detail) was how we would
have located the problem. Only enough was posted to discover
if you have sufficient tools and attitude.
First step is the most obvious. Visual inspection of all
receptacle box interiors for signs of water. Also safety
ground wires (for any receptacle after the GFCI) must be
inspected for separation even from neutral wires. Assumption
is that nothing - not even a light fixture or low voltage
transformer - is connected to any GFCIed receptacle or was
connected when failure happened. Everything connected to GFCI
must be known and confirmed by accounting for incoming and
outgoing wires in each electric box.
Jonathan Joseph wrote:
Well, I guess starting with the simple things first is
a good idea. Despite the fact that the external outlets
looked high and dry, I tried the hair dryer technique on
them. After this, the circuit would still trip, but I
thought I detected a slight pause before tripping. I
tried again after an hour and the pause was now slightly
longer (maybe 1/2 a second instead of instantaneous).
I looked at the outlets again, and while dry, I did now notice
that one of the them now seemed slightly corroded. When I
removed it and looked in the receptacle, sure enough, I found
a little water in there. It seems the water made its way in
during the heavy rain, but by the time I looked, there was no
external indication that anything had ever got wet. I dried
out the inside of the receptacle, put everything back together
and the breaker did not trip!
For now, I have sealed up the outside with a little masking tape
until I can pick up and install a new outlet.
As for the lights in the bathroom being on the GFCI, it's
probably because the particular type of fixture had a plug
outlet in it too.
If properly installed, then rain should never cause a GFCI
failure. IOW all exterior outlets are covered by a water
protective cover. Wires inside the outlet should have enough
spacing so that water (condensation) cannot create a
A neat thing about taking time to solve a problem. Its
called the power of knowledge. Even if that solution is not
complete, you will be learning enough that this and other
failures are quickly identified. If nothing else, keep up the
good work. Keep learning by using the lessons of experience
combined with the concepts in theory. You have eliminated the
water problem. Now to learn if that really was reason for a
GFCI trip. Per chance, per chance, per chance.
Jonathan Joseph wrote:
On Tuesday, May 25, 2004 11:12:32 AM UTC-4, JJ wrote:
*When you put the outdoor outlet back together make sure that the gasket is
good. Also caulk around the cover. I use GE Silicone 2 Gutter (Clear) ca
ulk for this. Home Depot sells it.
Several months ago I posted a photo on my Facebook page of an outdoor GFI r
eceptacle that was subjected to water infiltration. It looked as though so
meone put a torch to it. The DIY installer mounted an open face weatherpro
of lamp socket in the upright vertical position on top of the weatherproof
box. Water would land on the open bulb and trickle down the bulb socket in
to the weatherproof electrical box. In addition to replacing the GFI, I re
placed the socket with a sealed fixture and generously caulked.
I had this same problem for years; two electricians said there was
absolutely nothing wrong.
Then I took an electrical course and found one of my outdoor outlets was
bad. I replaced it and have been fine since.
Do you know how the circuit runs? I found the problem by opening the
circuit in various places to isolate the problem.
I would certainly suspect that one of the external outlets is the culprit.
The next time it happens, remove the cover and use a hair dryer on an
extension to blow hot air into and around the outlet. Do one for about ten
minutes and then try to reset the GFCI. If this doesn't help, then try the
other one. This might let you isolate the problem. You just might find that
the seals on the covers are not fitting tightly.
A couple of replacement outlets and seals for the outside outlets will
likely fix the problem and cost very little.
I would just replace them, but if you like you can try the drying them
out with a hair dryer next them.
Bathroom lights? I thought just the outlets were on a GFCI circuit,
the old code was. You have only one circuit breaker for all that?
Anyway, it almost sounds like something is soaking for a while before
it trips like a line that gets wet and slightly shorts to ground. Be
sure that you locate every outlet and then see if any outlet is
supplied by wire that is buried. Rather tedious, but if you can
figure out how the line runs start at the downstream end and
disconnect the line at the next box upstream and try the circuit
breaker and keep working further upstream (toward the circuit
breaker). Or, work the opposite way, i.e., work downstream from the
I'd buy a bucket of GFI outlets and place one at each location where
needed and remove the GFCI breaker. Then when any GFI outlet trips you
know which one it is and can better address the source of the problem.
George E. Cawthon wrote:
In my experience, and in other threads, I learned that you don't want to put
more than one GFI breaker/outlet on a circuit. They interfere with each other.
That said, I am having a similar issue with a string of outdoor lights I
installed up my driveway. I had a guy with a ditch witch come and bury segments
of outdoor 12 ga wire (the gray stuff that is supposedly ok to bury without a
conduit) from lamp post to lamp post. 7 posts in all. He actually put the wire
into that 1" black plastic tubing for further protection.
I have them all connected to a GFI outlet on my front porch.
In dry weather it all works fine. But after a heavy rain, the GFI trips,
sometimes immediately, sometimes after a delay of seconds or minutes.
So -- typical water problem somewhere. I finally isolated it to one segment of
buried wire, between posts 3 and 4.
Disconnect the wire completely at post 4 (hot, neutral, and ground), and it
still trips the GFI.
Disconnect the wire compoletely at post 3, and the GFI no longer trips.
So apparently there is a leak somewhere in the underground wire run between 3
and 4. I suppose it's possible that the ditch witch guy somehow skinned some
insulation off the hot wire, and when it gets wet, it conducts enough to earth
to trip the GFI.
This is a bummer, because I don't know if I can pull the bad wire out and pull a
good one in behind it or not. Maybe I'll just run that segment through some
trees and call it good. :-)
Yeah, no kidding -- the whole point of putting it into a tube is to protect it.
But not necessarily from water. More from digging. All the tubes are buried
under the ground, so water can easily get into them. The gray outdoor cable
itself is meant to be buried or just be outside, with no further protection. So
it must be a bare spot in the hot line.
If I can even get the wire out of the tube, I'll inspect it, but I doubt I can
pull it out. It's 50 feet long with curves along the way, and it's 12 ga. If I
can easily pull it then I will just to see what happened to it, but otherwise
I'll just do another run, up in the trees or something.
It's not the lamp -- I disconnected that.
Always something, eh?
Thanks for the reply.
Good point! I did not think of that. Should have though, because the GFCI
compares what goes out the hot line with what comes back in the neutral, and
when they don't match, then it disconnects, right? So anywhere it leaks to
ground will trip it.
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