Ground fault tripped by trailer connection - Montana Owners Club

bighornram · 08-16-2011, 08:17 AM

Our new trailer trips the gfi on my house when I plug it in.

I'm connecting the 50 amp cable to the back of the trailer, then adapter to 30 amp, then adapter to 15. This trips the gfi on my house. The breaker doesn't trip only gfi.

Any ideas on why this might occur?

Thanks.

Jolu · 08-16-2011, 08:46 AM

Several things come to mind assuming there are no problems with connections at the rig.
The first thing to consider is the house GFI. How old is it and what condition is it in. It may be near it's life end. Sometimes a new GFI will cure one that trips when it should not.
Another would be how long is the run to the unit. Is the 15 amp adapter at the end of the 30 amp adapter without a 15 amp cord run beyond that.
Is the air turned on in the unit or other high demand items?
These are my first thoughts.
Joe

BB_TX · 08-16-2011, 10:18 AM

The way a GFI works is that it has an internal circuit that compares the current flowing thru the hot leg to the current flowing thru the neutral leg. All current that flows into the hot leg should flow out the neutral leg. If they differ by more than a few milliamps, it will trip. A difference means there is current leaking out somewhere.
As noted above, I would consider changing the GFI outlet first.
A leak can be a ground fault between neutral and ground, that is a short somewhere between neutral and ground allowing some of the current to flow out the ground wire instead of the neutral wire where it is supposed to flow. With all wiring correct and all connected electrical devices good, there should be no current flow thru the ground wire (other than some possible induced current due to the electro magnetic properties of normal current flow).
It could also be a high impedance "short" in the hot wire. A short in the hot leg would normally trip the breaker. But if the "short" were such that it was a very high impedance (resistance) connection, then it could trip the GFI without tripping the breaker. For example, this could happen within an electrical device where insulation was beginning to break down, but had not completely failed yet.
A common cause of GFI tripping is water inside an electrical box or electrical device. The water provides a high impedance path that can be from either neutral to ground or hot to ground. Another is a screw that finally rubbed thru insulation either in a wire or in an electrical device. Or maybe a wire that has been rubbing on a piece of metal and wore thru due to vibration.
Your task will be to find the source of the imbalance. I would start by turning off all circuit breakers in the trailer, then plug it in, and see if the GFI remains active.
If it trips, then the problem is upstream of the main breaker panel.
If doesn't trip, then beginning with the main breaker, turn them on one by one until it trips the GFI. That will narrow down the circuit where the problem is.
Once you narrow it down to a specific circuit, then it is a matter of troubleshooting that circuit.

bighornram · 08-16-2011, 12:12 PM

Thanks for those tips, I'll start the troubleshooting process. I had my old trailer, Wildcat 28RK plugged into this outlet without problems so have to think it is something with the new setup. I asked the dealer about it and he told me he has seen this before, a couple had a bad heating element in the water heater, a couple they decided it was the multiple adapter connections. I have a 30' 50 amp cable to a 30 amp reducer pigtail to a 30 to 15 amp reducer pigtail which was then plugged into a heavy duty extension cord. I was able to plug into my 20 amp outlet which is not gfi protected and it didn't trip the breaker. It ran the ac and everything without a problem.

thor · 08-16-2011, 01:55 PM

sounds like too much cord and it is drawing to much juice through ths extension cord. also is everything is turned off before pluging the cord in?

bighornram · 08-16-2011, 04:27 PM

I don't think anything was on. No lights, nothing running though don't know what might draw but not be seen. The trailer goes back to the dealer tomorrow for an adjustment. I am hopeful they will plug into a gfi outlet with my wires/connectors eliminating the trailer as the culprit.

bighornram · 08-19-2011, 04:58 PM

Ok, got my rig back from the dealer today. He said they connected to a gfi connection and it didn't trip. Not reproduceable. When I got home I connected it with a new 50 amp twist lock to 30 amp 25 ft. cable. Reduced to 15 amp and it tripped my gfi again. I moved to another gfi circuit and it popped it too. So then as suggested I went out and turned OFF all breakers in the trailer. Plugged in and it didn't trip. So started with the main first, then started flipping the others on. Every time CONVERTER breaker trips the gfi.

dieselguy · 08-22-2011, 09:07 AM

No answer to the converter issue, I will throw out just my take on running the A/C on a 15 amp extension cord setup .... DON'T ... it will run it as you have experienced, but it's really hard on your A/C for extended periods. Wiring in at least a 30 amp plug on the side of your house is cheaper than a new compressor.

BB_TX · 08-22-2011, 09:23 AM

Don't have an answer as to why it trips your GFI and not the dealer's. Possibly yours is more sensitive than his. Or maybe his doesn't work.
If you have access to another GFI outlet, try it.

bighornram · 08-22-2011, 09:54 AM

Quote:

quote:Originally posted by dieselguy

No answer to the converter issue, I will throw out just my take on running the A/C on a 15 amp extension cord setup .... DON'T ... it will run it as you have experienced, but it's really hard on your A/C for extended periods. Wiring in at least a 30 amp plug on the side of your house is cheaper than a new compressor.

I did learn that with my old trailer. When I plug up to my house it is to put a charge on the battery and to pre-cool the fridge before putting food in it. I have a 20 amp non-gfi outlet (washer) that I can plug into if i need the a/c for any reason, which is really never.

bighornram · 08-22-2011, 10:04 AM

Quote:

quote:Originally posted by BB_TX

Don't have an answer as to why it trips your GFI and not the dealer's. Possibly yours is more sensitive than his. Or maybe his doesn't work.
If you have access to another GFI outlet, try it.

I happened to be working on this a little this morning again. I verified that my gfi in the house is not the problem as I connected to a second gfi'd circuit and it also tripped. I called the dealer and let them know about the converter breaker being the culprit. He did tell me their gfi is 20 amp where mine are 15 amp though my breakers are not tripping, it's the gfi. He called Keystone on it since he can't duplicate and therefore can't troubleshoot it there. He suggested switching the breaker connections to eliminate this being a faulty breaker in the converter box. I just did that and the converter still tripped the gfi using a different breaker in the trailer breaker/converter box. So I guess this must be a short in the converter/charge unit itself.

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