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GFCI at wall for shore power tripping


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New to us MH. Been at this storage bay for 3 weeks. At dealer always connected to 50 amp.  Have had issues on and off with the STORAGE BAY WALL SHORE POWER 20 amp GFCI tripping when I plugged in. Adapters were old and thought they might be leaking. No issues plugging in lights, portable battery charger, 1,500 watt hot air gun. Back from last trip and it connects OK. Two days ago, 100% trip. Changed oil on Onan 7.5 generator that day, do not think I did any thing on 120 but must have unplugged and replugged to start getting trip. thinking hard about what else I did those days. maybe tripped when generator dropped out and the house relay pulled in. When reset, GFCI is on long enough to hear the relay in the ESCO Transfer Switch j-box pull in and then drop out. Tried system running generator and second transfer switch relay pulls in and house has 120vac as expected. Replace 15 to 30 adapter and 30 to 50 adapter, new 20 amp GFCI in wall, breakers off in distribution panel (in theory, isolate issue b4 breaker panel), new 50 amp male plug on end of power cord (power cable reel), opened J-box between cable reel and house wiring. See my post on melted twisted wire nut. Fix this but still getting a trip. Pulled the input wires off transfer switch relay and capped with wire nuts, No trip. I had moved the cable in and out of the reel thinking it might be an issue with the conductors not making good contact but this "eliminated" that possibility.  Pulled generator supply wires off lower relay in TS j-box thinking maybe it was back feeding to the generator. Trips. This relay is open so probably should not be an issue but I was getting funny ohm readings across the contact. Probably has something to do with the control circuit board. With the wires off, current had no were to go.  There is a circuit board between the two relays that energize the relay coil that should be on. Both coils ohm at 80 which is correct per ESCO trouble shooting guide.  Pulled output wires off house relay going to fuse panel. Reset GFCI, Relay pulls in, no trip. Made up 120 vac pig tail and connected to the black and white wires on output of house relay (not going thru relay contacts) and feed one side of distribution using extension cord. NO trip. Switched over to the Red and White wires, plugged in and NO trip. I thought this told me that the issue was not in the house wiring. There are some burn marks on contacts of relay. I pull relay and head to Lowes hoping that they have the contacts as a replacement part for a motor starter. Nope. Buy contact cleaner and 1000/2000 grit emery paper. I know this is not a long term solution but thinking maybe they are pulling in at different times. I will at minimum replaced contacts. Polish and clean and reinstall. At this point, I have most of Saturday and a couple of hours after church on Sunday invested. Wife gets back in town. I hold the contacts in and she resets the GFCI, TRIP. Probably not because they are not pulling in at the same time. Pull the output to house wires off again. Reset GFCI, NO trip. Connect white neutral only, reset, TRIP!!!!!!!!! This really causes me to scratch my head. Pull white and connect red, reset, NO trip. Add black with red, reset, No trip. Pull out multimeter, only milliVolts on white lead to ground, black and red. I had the cover off the distribution panel earlier but put it back. Tomorrow, I will relook and test the ohms from the white to the ground. It should be zero. I may pull the white wire off the ground lug at distribution panel to see if the relay will pull in. Owner of storage facility is a great guy and was there when I swapped the GFCI. He has no suggestion. It is NOT an option to replace the GFCI with a 20 amp duplex outlet.  

There is a 3" cube black box hanging off the bottom of my transfer switch. May be some sort of capacitor to minimize arcing. I had pulled the two leads to the black and red wires off their terminals with no change in the trip. Tomorrow, I will call ESCO to find out more about this device. I will also pull the lead off the white wire to see if maybe it is conducting to ground though that is what you want, the neutral and ground tied together.

My background is offshore oil platform controls systems and I have done a lot of trouble shooting over the years. There is a solution to this. Hoping maybe someone has a good direction to investigate. If I can not find the issue tomorrow, I will start calling some of the mobile RV services and pick their brains enough to see if they can contribute something to the solution.

I am sure learning a lot about my MH. When I got home today, my MonacoWatts x-braces were on the from porch. I did get the rear of the MH up on blocks today and will take an hour or two tomorrow to get them installed. 

I would appreciate any good suggestions.


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I didn't follow your troubleshooting tips very well, so my comment may or may not be helpful.

If you have an MSW inverter, GFI outlets don't like MSW at all.

I replaced my GFI outlet in the bathroom with one from Home Depot, Leviton I think.  It would trip any time the inverter was active.

Xantrex did some testing that applies to all MSW inverters.  You can find the document here:

Based on that document, I bought a Pass & Seymour GFI.  I had to get it on ebay.

No problem at all since I installed the Pass & Seymour GFCI



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I found the cause of the trip. Some have said they had trouble working thru my trouble shooting history. I will re-discuss the test that I very much miss interpreted. I had hooked up a TWO wire pig tail to the black and white and then red and white feeding the main distribution on the house side of the transfer relay and neither tripped the GFCI. What I missed was I did not connect a ground to the system. The every thing connected normal trip was because shore power GFCI was seeing zero ohms between the neutral and the ground. With the two wire pigtail, it saw the connection as open not knowing there was no wire to the ground.  I pulled the inverter, water heater, refrigerator, and several other wires of the neutral bus and still had trips. This morning I pulled the three left most and tested and now had an open circuit between the ground and neutral bus. I reattached the first two and still open. The third breaker/neutral was the engine heater receptacle in the engine compartment. Open this receptacle cover and it is a GFCI. Remove cover and as I am pulling the GFCI out, the neutral is loose from the clamp. The bare ground conductor is connected to a screw in the side of the metal box for grounding the box and routed directly behind were the white wire is connected. I rearranged the ground wire more at the bottom of the box and re-tightened the terminal to the white conductor and no more GFCI trip.  It does not appear that this GFCI had ever been used. 

Using the two wire pigtail without a trip gave me the false impression that the house wiring was OK. That cost me hours of trouble shooting. If this happens again, the first test would be with all the breakers OFF. If it still trips, the issue is up stream of the breakers OR I will check the resistance between the ground and neutral inside the breaker box. If ZERO ohms, I will know it is a grounding issue, not a power issue.

I count at least 4 GFCIs within the MH wiring being feed by my shower power GFCI. Some have said that stacking GFCIs will not work. Might be best not too. Not my building and I am obligated to have a GFCI supplying shore power. If every thing is connected correctly, stacked GFCI can work.

Pretty much always a solution. Just interpreting each bit of information correctly.

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More that 0 ohms can cause a GFCI to trip.  GFCIs trip with 5ma leakage. That is about 24K ohms. 

Some types of GFCIs don't work in series but I've never had a issue, just something to be aware of. When doing my PDI for the current rig the 3 light tester showed a open ground on all of the kitchen plugs - Monaco had not connected a  ground wire and the original owner never checked.

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