"General" circuit causing shore power GFI to trip - help please

[riprobbins]

We have a new 2250RK (30A service) and after three successful outings to various campgrounds, all using shore power and having no electrical issues, we returned home and connected our trailer to our house power. The receptacle we connect to is on a 20A GFI-protected circuit for our garage, and it is the same one we had connected the trailer to in the past without issues.

The garage GFI receptacle would trip every time I'd connect the trailer's power cable to the house. None of the breakers in the trailer's panel would trip -- just the GFI receptacle in our garage. I started isolating circuits on the trailer one at a time and found that the circuit labeled "General" is the one causing the GFI in the garage to trip. We THINK we have determined that the only things the General circuit supplies power to are 1) an interior receptacle in the slide near the stereo into which the TV is plugged, and 2) a receptacle in the outside refrigerator mechanical bay into which the refrigerator is plugged. The fridge receptacle is down-line from the TV receptacle. Everything except the fridge and this interior receptacle seem to operate fine with only the General circuit breaker switched off.

I connected the fridge's 120V cord plug directly to the garage GFI receptacle with an extension cord and verified the fridge works properly. I disconnected the TV receptacle from the wire coming from the breaker panel, and the General circuit breaker still trips. I don't think there is anything connected to this circuit now, since I've disconnected the wire from the TV receptacle and the fridge receptacle is down-line from it.

I'm sort of feeling my way in the dark here but I'm thinking the problem could be either a faulty circuit breaker or a fault in the wiring between the circuit breaker and the receptacle that the TV plugs into. I don't know what are considered "typical indications" of a faulty breaker, or if what I'm observing is consistent with those. I read a previous post about pooled water above the insulation mat causing a short in a wiring splice, so I may next try to trace the wire.

Any help is much appreciated.

Rip

[Hokensalem]

You may want to plug into a regular outlet. I have found 2 gfi recept's don't like each other.

[xrated]

Another possibility is that you mentioned that the problematic circuit is feeding stuff in the slide. It's possible that the wiring could have gotten pinched over time as the slide is being used

[jkwilson]

Any chance of moisture in any of the areas? Even condensation on an outlet or cord can be enough to trip a GFCI.

[Hokensalem]

Your problem is the GFI in your garage is seeing a short between the equipment ground and the neutral in the RV. Since the ground and neutral are bonded together in the RV electrical panel it thinks that's a fault. When you test a GFI receptacle all you do is short the ground and neutral together to test the GFI. If the GFI is good then it will trip. If you plug into a non GFI circuit then you will be OK. All is well with both electrical systems, Your garage GFI just thinks there's a problem down stream.

[riprobbins]

Your problem is the GFI in your garage is seeing a short between the equipment ground and the neutral in the RV. Since the ground and neutral are bonded together in the RV electrical panel it thinks that's a fault. When you test a GFI receptacle all you do is short the ground and neutral together to test the GFI. If the GFI is good then it will trip. If you plug into a non GFI circuit then you will be OK. All is well with both electrical systems, Your garage GFI just thinks there's a problem down stream.

Hokensalem, thank you. Here is additional information: 1) the garage GFI circuit which has been giving us fits is the same one into which we have had the trailer plugged, off and on for the past 3-4 months in our driveway with no issues. 2) This morning I could not repeat the condition that I had all day yesterday, meaning that now the General circuit does not trip regardless of whether the trailer is plugged into the GFI circuit or a non-GFI protected circuit (so now I can ~upgrade~ the problem to "intermittent" (groan). 3) It rained all during the drive home on Monday but is dry today (Wednesday). jkwilson mentioned moisture as a possible culprit, so I started pulling down the plastic barrier membrane and it was holding a fair bit of moisture. I guess it may have been tire spray. I could not see a clear smoking gun but I believe some drying out has occurred. More alarming is how the wire "bundles" just hang down and lay across the surface of some foil sheeting (I guess it's a vapor barrier) that lays on top of the plastic barrier.

[Hokensalem]

Hokensalem, thank you. Here is additional information: 1) the garage GFI circuit which has been giving us fits is the same one into which we have had the trailer plugged, off and on for the past 3-4 months in our driveway with no issues. 2) This morning I could not repeat the condition that I had all day yesterday, meaning that now the General circuit does not trip regardless of whether the trailer is plugged into the GFI circuit or a non-GFI protected circuit (so now I can ~upgrade~ the problem to "intermittent" (groan). 3) It rained all during the drive home on Monday but is dry today (Wednesday). jkwilson mentioned moisture as a possible culprit, so I started pulling down the plastic barrier membrane and it was holding a fair bit of moisture. I guess it may have been tire spray. I could not see a clear smoking gun but I believe some drying out has occurred. More alarming is how the wire "bundles" just hang down and lay across the surface of some foil sheeting (I guess it's a vapor barrier) that lays on top of the plastic barrier.

Moisture will wreak all kinds of havoc in GFI circuits. It doesn't take a lot either.

[xrated]

Your problem is the GFI in your garage is seeing a short between the equipment ground and the neutral in the RV. Since the ground and neutral are bonded together in the RV electrical panel it thinks that's a fault. When you test a GFI receptacle all you do is short the ground and neutral together to test the GFI. If the GFI is good then it will trip. If you plug into a non GFI circuit then you will be OK. All is well with both electrical systems, Your garage GFI just thinks there's a problem down stream.

The neutral and the ground in the RV Electrical panel should not be bonded together. Then N-G bond is only done in the first panel that is the source of the supplied voltage, in this case, the Electrical panel that is in his house that feeds the circuit to the garage.