Bigfoot tripping house GFI

[TxGearhead]

2008 Bigfoot 9.4. Replaced the converter early this spring only because it was boiling my batteries. Got a Progressive from Best Converters. Son and I replaced it. He works with DC a lot on the job. I haven't actually used the camper since, for a variety of reasons. I usually plug the camper into a house 110volt outlet every 4-6 weeks to keep the batteries up. The exterior outlet I use is a GFI. Several weeks ago, after it was plugged in, I noticed the LED lite on the extension cord wasn't on. The outlet had tripped its GFI. I reset the GFI and same thing again. Went to another GFI outlet and it did the same. This hasn't happened before. Then used a non GFI outlet in my garage and all seemed well. Charged the camper for several days.
Only thing I can think of besides a loose connection on the converter is the ground wires that are bolted to one of the Bigfoot tiedowns. I had to re-arrange them a bit when I installed a Torklift tiedown "stiffener".
I haven't done anything yet. It's only 95F and 90% humidity. I'm thinking the first somewhat cool morning I'll dive into it. Guessing I'll clean the eye connectors on those ground wires and be sure they have clean metal to metal contact on the tiedown. Oh, I did replace the30amp plug on the camper cord.
I'm not sure how to check ground continuity. Maybe ohm from the plug ground to any ground I find in the camper?
Or, since it takes only milliamps to throw a GFI, just ignore it??
My house outlets don't throw GFI on anything else.

edit add: Eh, wait a minute...I had a brain flash. I was using a $4 30amp to 110volt adapter. Little hockey puck thing. Tomorrow I'll try a dogbone. But y'all keep thinking how to diagnose this, or ignore it.
Thanks in advance.

[TxGearhead]

Thanks, will do if and when I get the HappiJacks working.

[bigfootford]

Good that you found that it was the fridge.

You can disconnect the hot lead and neutral to the heater element and retest. That will verify that the heater element is defective and has an a slight short, not a complete short as that might trip the campers breaker.

Jim

[time2roll]

TxGearhead wrote:
AC heater circuit burned up and shorted?

Assuming the fridge is connected to 120v power... not sure it is burned up but I do suspect there is a leakage to ground.

If you can isolate the circuit an ohm meter should find the issue.
Otherwise a visual inspection and adjustment is probably needed.

[toddb]

Inductive loads cause ghost trips. Dedicated RV outlets are not GFCI protected, the outlets in the RV that need GFCI should be on there own. Heater elements and charge converters can do this, even though progressive dynamics says it 'should be ok'. I presume you have a gfci in the camper, so now you have 2 on the same circuit and that can also cause ghost trips. Our house is an old build and had a GCFI breaker, and later someone added one in the bathroom. The breaker tripped randomly, after the breaker was removed and the gfci placed correctly in the circuit it's been fine.

[TxGearhead]

I spoke too soon. This morning I plugged the Bigfoot back in. The microwave lights came on and I threw the battery isolator to "use". Then a couple minutes later I was walking by the fridge vent and heard the ignitor going off, then the burner kick on. Then I went and sat in the garage a bit and thought about it. Why did the fridge go to propane? I thought it defaulted to AC. Checked the GFI and yep it tripped.
Scratched my head a bit and remembered the attached threads from earlier. So I took the bottom vent cover off the fridge, all looked well except a dirt dobber and a wasp nest. So I unplugged the fridge. Plugged the extension cord back in and turned the fridge on.
If it works good on gas I'm OK with that for now. I'm trying to get to the sprint car nationals in Charlotte in a few weeks and don't have hook ups any way. May drive back home through the Smokies.
Just looking behind the fridge I saw no burned wires or any other damage.
AC heater circuit burned up and shorted?

[TxGearhead]

I think it's fixed. May have been too easy. I used a dog bone instead of the hockey puck adapter, and used a different extension cord. The cord I was using looked a little rough and I had actually taped up a spot on the exterior sheathing. No bare wires showing though. This afternoon I'll plug the extension cord in and see if it throws the GFI.
So, it's been plugged in for an hour and all seems well.
Thanks for all the help diagnosing. I learned a lot and I hope others did as well.

[wnjj]

BurbMan wrote:
Ok, maybe on the west coast....GFCIs work by comparing the current flowing into the circuit via the hot wire and returning via the neutral, that's how they detect a neutral/ground short. because that current is "leaking" to ground instead of returning via the neutral. Without incoming current via a hot wire, the GFCI has no way to measure if any is leaking to ground, the means by which it identifies a neutral/ground short.

If a given circuit in the camper has a neutral/ground short, but that breaker is turned off in the camper, the house GFCI will not trip. Why? Because the breaker in the camper is stopping current from flowing into that circuit and revealing the fault by leaking to ground. Make sense?

What you're saying is equivalent to being able to find a leaky pipe with the water turned off.

GFCI’s actually attempt to inject a small current into the hot and neutral pair of wires. If there’s a loop formed by the neutral and ground (connected in the source panel and fault connected at the load), current will flow and it will detect that without involving the hot wire.

Here’s some reading for you. Starting about page 3 is where we got into the details of a GFCI. https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29619499

Take a paper clip and short out the ground and neutral of a GFCI protected outlet and see for yourself.

It’s also the reason why a bad fridge element with insulation worn off can trip a GFCI, even when the fridge is not on electric (i.e. the power switch relay is open).

[BurbMan]

Ok, maybe on the west coast....GFCIs work by comparing the current flowing into the circuit via the hot wire and returning via the neutral, that's how they detect a neutral/ground short. because that current is "leaking" to ground instead of returning via the neutral. Without incoming current via a hot wire, the GFCI has no way to measure if any is leaking to ground, the means by which it identifies a neutral/ground short.

If a given circuit in the camper has a neutral/ground short, but that breaker is turned off in the camper, the house GFCI will not trip. Why? Because the breaker in the camper is stopping current from flowing into that circuit and revealing the fault by leaking to ground. Make sense?

What you're saying is equivalent to being able to find a leaky pipe with the water turned off.

[bigfootford]

Just for grins, unplug your fridge AC cord inside the outside fridge access cover.
Reset your GFI and see if it trips again.

Some reading here if anyone is interested.

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/19658290/srt/pa/pging/1/page/1.cfm

More reading on the subject. Nice to have an understanding of the fridge and GFI's.

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/19726244/srt/pa/pging/1/page/1.cfm

Jim

[wnjj]

BurbMan wrote:
Yes the breakers only isolate the hot, but the GFCI won't trip with the hot disconnected. Some things in the camper you can't "unplug", items like the converter and HW heater are usually hardwired.

If you start with the breakers, you can isolate what circuit the problem is on, or if the GFCI still trips with the breakers off then the issue is with the cordset.

Not true. GFCI’s can absolutely trip with the hot disconnected. They can test for and trip by simply having a neutral to ground short without any current flowing. So while turning off breakers may reveal something, it may not.

If ANY place inside the camper has a neutral to ground short, the upstream house GFCI will trip, not just with a power cord short.

To completely isolate, you may actually have to open the camper panel and disconnect the neutral wires until the fault clears.

[TxGearhead]

Thanks! I'll start with the breakers.

[BurbMan]

Yes the breakers only isolate the hot, but the GFCI won't trip with the hot disconnected. Some things in the camper you can't "unplug", items like the converter and HW heater are usually hardwired.

If you start with the breakers, you can isolate what circuit the problem is on, or if the GFCI still trips with the breakers off then the issue is with the cordset.

[Sjm9911]

Sometimes a large start up draw will read as a fault. Thats why they dont plug older style washing machines and such into them. When they hit the spin cycle the outlet would trip. Also, make sure the gfi is a 20 amp outlet. It could also be moisture problum in the outlet. 90 percent humidity isnt good for gfi outlets.

[wnjj]

BurbMan wrote:
Go into the breaker box in the camper and turn off the breaker that powers the converter/charger. Then plug the camper into the house GFCI and see if it trips. If it doesn't trip, then you have a problem with that circuit in the camper, and it's likely the converter/charger since you recently changed that component. Either it's defective or you wired something wrong.

If it still trips, then turn all the breakers off in the camper, then plug in again. If it still trips then the problem is likely the cord or plug, if not, turn breakers on one at a time until the GFCI trips, and your problem will be on that circuit.

Turning off breakers will not isolate neutral/ground issues since the breakers only disconnect the hot. It's best to unplug any/all appliances (including the fridge). If it still trips with everything unplugged and the breakers all off, there's an issue behind the receptacles or in the power cord.