Need advice about a GFCI outlet

Ok this isn't RV related but I know there's a few of you who know electricity out there so I'm asking for some advice. Last year at my cabin we trenched and laid in ground rated 3 wire to put outlets at various spots around the cabin yard. All total we did 4 lines, each line independent with their own breakers. 3 work flawlessly, but one is giving some problems. It's a 15 amp gfci outlet in a weatherproof box, attached to a 15 amp breaker in the box, nothing else on it. It worked fine from the fall through the winter, but this spring started tripping constantly. Then one day I heard a rapid ticking and found the outlet going nuts inside the the cover. So I turned off the breaker, I undid the outlet, and installed a regular non gfci outlet in its place that has worked worked fine all summer. When I opened it initially I did find water in the supposedly weather proof box so I used a compressor to blow it out and then I put better screws to hold the faceplate and foam tighter to the body. At one point I bought another 15 amp gfci outlet and installed it only to find it was tripping the reset button instantly without anything plugged in. I'm hoping it was just by chance a bad outlet that I bought, but i don't know. I'm bringing another new one up this weekend to see what it does. Does anyone know why an outlet without any load would trip on its own? (And just to be clear this is a three wire setup, hot, neutral, and ground, and as far as i can see all wires are connected where they're supposed to be on both breaker panel, and outlet)

Moisture may have got into the cable feeding the box, thereby causing continuity between the actual wires. It only takes a small amount (5ma) of leakage to trip the GFCI. The only way to really check the cable is with a megger.

My guess it's just a defective GFCI outlet.  It happens

spencerpj said:

My guess it's just a defective GFCI outlet.  It happens

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I doubt it's the outlet. It has happened on 2 GFCI outlets.  It did work fine on a NON-GFCI outlet. I'm thinking like goat,  that it's something in the wiring.

To add to what kdbgoat posted, GFCI 120vac outlets are designed to fault (trip) when current to the ground wire is in the range of 4-6 milliamps ( or .004 to .006 amp).  The outlet fault circuit measures the difference in current between the HOT wire and the Neutral wire to determine the leakage.  All current being drawn from the hot wire needs to return via the neutral wire.  Any current that is not returned via the neutral wire is leakage current.

Bad cable won't affect a GFCI outlet unless it's hooked up to the load side of the receptacle. If I understand the circuit, it goes from the panel around the yard and feeds several outlets in their own boxes. If each outlet is connected as a stand alone device then it's possible that the load side sticker is wet or the ground wire might be touching the neutral screws on the device. Bad feeder cable won't trip the device, only a bad load cable can do that. Don't feed through to the next GFCI on the circuit as it's redundant protection.
Also, buy a special weather resistant GFCIs to use in those boxes as required by the NEC. Indoor rated will go bad from the moisture in the box.

I would try replacing the breaker for the circuit that?s tripping. Don?t go buy a new breaker, just disconnect a current circuit and attach the circuit that giving you trouble with the GFCI. Make sure you have the GFCI installed first. Swap the wire on the breaker and see if the GFCI holds. If it doesn?t, then most likely water got to the wire itself, somewhere between your breaker box and where the wire goes into it?s box. Also don?t have any load attached after the GFCI. Have just the home run attached to the GFCI. See if it holds. If that holds, then the problem is between the GFCI and the load it?s protecting. Does it matter what you plug into it? Sounds like it just trips on its own.

I'll reiterate that each outlet has it's own 3 wire strand and breaker. So this outlet comes from the breaker panel, down the conduit into the ground, 150 feet underground, and the up through the conduit to the outlet itself. The thought had occurred to me that an animal may have chewed on it but they would have to get through the outer coating, plus the inner individual wire coating, and the depth is somewhere between 2 1/2 to 3 feet deep, as far as the blade of the ditch witch.

Jim18655 said:

Bad cable won't affect a GFCI outlet unless it's hooked up to the load side of the receptacle.

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That is what I thought too but it appears that is not the case in this case.

IN THEORY. a GFCI does not need the safety ground lead at all. IN THEORY. but I'm at a loss here. Does sound like some source of leakage.

Double check to insure you have hooked up the wired PROPERLY. that is to the LINE IN side of the GFCI receptical.. All 3 must be on the IN side. if there are 2 Green wires.

If I'm understanding you correctly (correct me if I'm wrong), you are saying that the non GFCI outlet that you put in after the GFCI outlet had problems, is tripping the breaker at the panel?  Is that right?  If that's the case, you have wiring problems between the breaker in the panel and the wiring going out to the recept.

xrated said:

If I'm understanding you correctly (correct me if I'm wrong), you are saying that the non GFCI outlet that you put in after the GFCI outlet had problems, is tripping the breaker at the panel?  Is that right?  If that's the case, you have wiring problems between the breaker in the panel and the wiring going out to the recept.

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He said in his first post "So I turned off the breaker, I did the outlet, and installed a regular non gfci outlet in its place that has worked worked fine all summer"

I assumed, maybe incorrectly, that only the GFCI was tripping. One problem with GFCIs is that they pretty much fill a regular size bell box and anything can touch the screws on the receptacle.

The non gfci outlet is working no problem, not tripping the breaker or anything. The outlet receptacle is a waterproof plastic box with the spring closing lid. The 2 gfci outlets that have been in there never tripped the actual breaker either. I'm pretty sure the first one fried itself somehow, possibly due to the water that managed to get in there, it smelled burnt when I pulled it out. The second gfci I put in wouldn't even stay on, just trip it's own reset button instantly.

Pull it out of the box and make sure nothing is touching any of the screws or wires. Turn the circuit on and see if it works. If it works then something is wrong in the box. If it still trips then replace the GFCI. You should be buying the weather resistant type for outdoor use. They'll last longer in the damp conditions.

Sounds like you may have one of two conditions, maybe both?
Let's look at the facts; water intrusion, GFI tripped, burned smell- to me that indicates this circuit shorted out due to the water intrusion and fried the GFI (burnt smell).


Regular outlet worked fine all summer- did you test it for cross polarity? Does the hot go to ground? Simple outlet tester can confirm or deny if the outlet is wired properly. While it may have a short, it may not be a strong enough short to trip the breaker, a strand of wire or two will suffice to trip a GFI constantly and won't be enough to trip a circuit breaker. Is this wire stranded or solid?

Questions for you:
When installing, did you nick or slice the insulation surrounding the hot?
Is this direct burial cable or did you bury in conduit?

IF direct burial cable and you nicked the hot it may be making contact with the nuetral or ground at teh nicked area. Especially if this area is still wet.

If this is conduit, is there standing water in the pipe?

This is solid copper 10 ga I believe in ground rated direct burial, not in conduit, with the exception of the 3 foot conduit that it rises out of the ground from on the shed wall. I don't see how I could've nicked anything on it because this is heavily coated wire. All three interior wires are coated, plus the outside rubber is thick, I had to work like a dog to remove enough outer covering to get to the three wires, which then I only stripped 1/4" or so just enough for the various contact points. Also, the 3 foot conduit rise is plastic with the proper bushings on each end to supposedly not give any sharp edge to rub against.

150 feet.  No conduit.

Critters.

I had a similar problem with pool lighting.  Every time it rained, and for several weeks afterwards the gfi breaker would fault when you switched the light off.  Once the ground got dry it worked fine.

Critters in deeply buried wires?  Must be moles or rabbits, and even then Type UF wire is really hard to chew through. Not tasty either. Almost has to be a neutral shorted to ground and that is highly unlikely in UF wire - the insulation is molded around the conductors.  It conceivable, but I'd be looking at that add-on 3 ft of conduit and the box.  Much more likely.

Of course the non-GFCI works fine. How can it exhibit a Ground Fault if it doesn't have any way to test for one? It just ignores any current flowing in the ground wire instead of the neutral.

Gary RV_Wizard said:

Critters in deeply buried wires?  Must be moles or rabbits, and even then Type UF wire is really hard to chew through. Not tasty either.

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We have many chipmunks here and they dig deep into the ground. Don't know if they would chew on wires.

Ground squirrels too, but few of them dig that deep and even fewer chew on tough molded plastic.  There is no cotton or paper inside to attract them as in Type NM wire.  The place to look for critter damage, if any, is at either end, where the wires comes up out of the ground.

I repeat: I'm not saying "impossible", but that would be down near the bottom of the list of things I would be investigating.