GFI trips on new circuit

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ChakJ

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Hi-

I am struggling with an electrical issue and would be glad for some advice.

I am trying to get an outlet into a new boathouse for a boat lift rated at 11 amps. So, I got 250 feet of 12/3 cable, put in a 20 amp breaker in the house, and ran the cable through pvc conduit (outside) buried about a foot deep. (Ended up using about 220 feet of the wire with all the turns, though the distance is only about 140 feet.) I put a GFI outlet at the first of the three outlets to ensure GFI protection.

Carefully connected all the outlets and the outlet tester confirms correct....

The problem is that the GFI breaker in the outlet pops about a second after the breaker is turned on.

Tested the voltage at the end of the line before the outlet, and it exactly matched the house reading 121.1 (if I remember correctly.) The outlet tester shows everything wired correctly. And a normal outlet works fine.

I tried putting a 20 amp GFI breaker on the main panel, but it also trips instantly when powered on. (Although both its lights come on indicating arc fault and ground fault…) (This is a siemens box, with siemens breakers.)

Any advise about why the GFI might be tripping? I read that they will trip at anything more than a 4 milliamp loss, or if the neutral and ground wires are touching, but this doesn’t seem to be the case.

The cable was intact and undamaged since we touched about every inch of it feeding it through the conduit….

Thanks
 

Reach4

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Unplug anything from the 3 outlets. I presume nothing was plugged in during your troubleshooting, but I thought I might mention it anyway.

Disconnect the output terminals from the GFCI outlet. Does the GFCI still pop? Probably it will not. In that case, the problem is downstream. You can turn off the breaker, and look for continuity, with an ohmmeter, between the disconnected hot and neutral wires to ground. There should not be continuity. Chances are that one of the isolated wires will show leakage of 24000 ohms or less.
 

ChakJ

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Thanks Reach... As you guessed, nothing was plugged in at all when I was doing the tests.
And yes, I also should have mentioned that the GFCI still popped when I disconnected everything downstream from it.

I did not check for continuity between the neutral and ground, or the hot and ground, but I will will do that next.
Thanks again.
 

Reach4

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And yes, I also should have mentioned that the GFCI still popped when I disconnected everything downstream from it.
If you are saying that you disconnected both wires from the GFCI output terminals, and the GFCI breaker popped, that would only be explained by a bad GFCI it seems to me. Maybe I am missing something. The AFCI breaker in the panel tripping could be caused by a bad GFCI outlet arcing, I guess.
 

Cacher_Chick

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Hopefully you are using UF cable, as regular NM is not rated for use in conduit, buried or otherwise. I agree with Reach in that you likely have a damaged cable which is allowing leakage between the conductors. I am guessing that you did not bring the conduit all the way to the panel, so any clamps or staples used on the cable between the panel and new connection point are also suspect.
 

jadnashua

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My bet is a crimped wire somewhere. I fought with a randomly tripping GFCI for awhile, and just ended up running a new wire since the existing one was buried in the wall...has worked fine since. Now, it's possible that that GFCI receptacle is bad...have you tried it temporarily somewhere else?

While things are safer with an actual ground wire, the GFCI will work without one. You said 12/3...unless you're running a switched circuit or a multi-branch circuit, why the extra wire? (Note, I may not be using multi-branch correctly here) But, if you're using a two-pole breaker and planning to run two circuits, sharing the neutral, with a GFCI, you're going to have problems with the GFCI...it measures the power going out one lead, and what is coming back on the other, and if they are not equal within 4-5ma, it will trip...it doesn't need the ground to work. The concept here is that any power going out one lead MUST come back the other to complete the circuit, and if some isn't, it's a fault, usually leaking to ground, thus they call it a ground-fault. It could be leaking anywhere, and may have nothing to do with the actual ground wire in the cable - the power flow must be equal in both leads, or there's a problem.
 

ChakJ

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Reach- Yep- disconnected both wires.. that's why I was scratching my head too- was hoping that if it was a bad gfi outlet, that putting the gfi breaker would work. I'll test the gfi outlet on another circuit.

cacher: Yep- using UF, just wanted to conduit also to minimize damage if someone hit it with a shovel in the coming years... It's true that I didn't run conduit to the panel though (inside the house I just clamped it. I can try removing the clamps.

jadnashua- Used 12/3 because we had it, but the red wire is capped at both ends and not connected to anything. But other than that, it's the simplest circuit possible- UF 12/3 from breaker box through conduit to an outlet, then to another outlet, then to another outlet (end.) I took the last two outlets out of the equation to see if I could find the problem...

So I think the first thing I'll do is check resistance between ground and neutral (with the breaker OFF), then remove the clamp/staples (to see if that's the problem) and check the GFI outlet on another circuit. Should have time to look at this Monday.
Thanks again all.
 

Reach4

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I don't see how a problem with the UF could trip a GFI outlet at the end. If if that was an AFCI breaker outlet, then I could see arcing upstream in the UF tripping that.
 
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Cacher_Chick

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I don't see how a problem with the UF could trip a GFI outlet at the end. If if that was an AFCI breaker outlet, then I could see arcing upstream in the UF tripping that.

I agree with Reach, a pinched wire could explain the GFCI breaker trip, but not a GFCI receptacle properly wired at the end of a circuit.
 

WorthFlorida

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All this going on we'll assume that you properly connect the power to the input side of the GFCI. The yellow tape is where to outlets down stream are connected to. If the GFCI breaker in the panel trips, it is then the wiring. Maybe when it was being pulled through the conduit one of the wires was skinned.

It does sound like that this is a new circuit in new conduit. Just be sure that the WHT (neutral) is not connected to any other circuit in a juncture box somewhere.


gfci.jpg
 
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jadnashua

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He fed through the GFCI to two additional receptacles...remove that from the GFCI and see if it still trips.
 
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