Electrical help for my Brother in Law with SOB

Chewie · 04-16-2016, 06:35 AM

My BIL bought a new Thor Quantum Class C, PDI went well but since he's been home, the shore power keeps blowing the house GFI instantly. He's tried multiple outlets on his house to see if there is a change and it keeps doing it. So essentially, there is no shore power. Worked at the dealer a few days ago. I was trying to help him over the phone last night, he was saying he can run everything on the generator, and he also has an inverter that's working but obviously killing the batteries after a while. From what I can gather he's using the 30a cord stepped down to 15a adapter and extension cord. He wasn't trying to run any big appliances on the 15a, just outlets and TV. Other than checking for breakers tripped or blown fuses, what else should I look for? I'm heading over today there to try and help out. We have a trip in 5 days so we want to get it working on shore power. Thanks.

clr · 04-16-2016, 06:47 AM

Plugging a RV into a GFI outlet is not a good idea. The explanation for not using a GFI outlet is long, but your house is earth grounded and your RV is a floating ground system. You should not mix the two grounding systems. Also you should not have a GFI system feeding another GFI system. All RV's have at least one GFI wiring circuit. My first action would be to plug the RV into a non GFI outlet in the home and see if that works. Second I would make sure that the extension cord is able to handle the 15 amps. You should not use a standard 16 or 18 gauge extension cord to plug in the RV. I would recommend a 10 gauge or at least 12 gauge. All so the extension cord should be as short as feasible.

nomad297 · 04-16-2016, 06:51 AM

Quote:

Originally Posted by clr

Plugging a RV into a GFI outlet is not a good idea. The explanation for not using a GFI outlet is long, but your house is earth grounded and your RV is a floating ground system. You should not mix the two grounding systems. Also you should not have a GFI system feeding another GFI system. All RV's have at least one GFI wiring circuit. My first action would be to plug the RV into a non GFI outlet in the home and see if that works. Second I would make sure that the extension cord is able to handle the 15 amps. You should not use a standard 16 or 18 gauge extension cord to plug in the RV. I would recommend a 10 gauge or at least 12 gauge. All so the extension cord should be as short as feasible.

Exactly my thoughts.

Bruce

Chewie · 04-16-2016, 06:56 AM

Ok, thanks. I will take my power cord along to see if it works any different

ScottBrownstein · 04-16-2016, 07:14 AM

X2. No reason for a GFI feed to the RV, it is not designed for this. It has it's own GFIs where necessary. Straight feed from the house. There is no tie between ground and neutral in the RV circuits and serial GFIs are a bad deal.

shughey00 · 04-16-2016, 07:23 AM

deleted....answers were given above by the time I was done typing so... No need to repeat. Use a non GFI outlet is all.

uhduh camping · 04-16-2016, 07:47 AM

You might want to take your dog bone adapters in case BIL has an issue with his. It's just one of the variable that changed since leaving dealer.

Chewie · 04-16-2016, 08:50 AM

Quote:

Originally Posted by uhduh camping

You might want to take your dog bone adapters in case BIL has an issue with his. It's just one of the variable that changed since leaving dealer.

Yes I did bring it. Just in case. I should be there around lunch time and hopefully it's something simple and I'll follow up. Thanks

PSU Turf · 04-16-2016, 11:40 AM

At home I use a 20 Amp GFI for my shore power with no issues. I had a similar problem to what Chewie is describing. The trailer was still winterized so there was no water in the hot water tank. I had forgotten to turn off the electric to the water heater. The element would overheat and trip the breaker, in my garage, shortly after plugging in. Doh. Lesson learned.

Chewie · 04-16-2016, 01:53 PM

Update, I have since switched him to an outlet inside his house, non-gfci, working on shore power. The instant the cords are connected to the gfci it trips. Even though all the breakers inside the motorhome are off. No blown fuses, breakers seem fine. I believe it's his house??

clr · 04-16-2016, 02:01 PM

It is not the house it is a combination of the house and the RV. GFI outlets monitor the power going out the hot lead and returning on the ground lead. If there is a very small difference the GFI assumes that the missing power is going to ground somewhere else and the GFI will trip. A GFI outlet also times the power out and will trip if it does not see the same power return on the ground lead within milliseconds. Switching power supplies like the converter in the RV will delay the current being returned on the ground lead. This is just the way they work and is not a problem. But the house GFI sees this as problem and will trip the home GFI. There is nothing wrong here and this is normal operation for both the RV and the home.

Chewie · 04-16-2016, 02:14 PM

Quote:

Originally Posted by clr

It is not the house it is a combination of the house and the RV. GFI outlets monitor the power going out the hot lead and returning on the ground lead. If there is a very small difference the GFI assumes that the missing power is going to ground somewhere else and the GFI will trip. A GFI outlet also times the power out and will trip if it does not see the same power return on the ground lead within milliseconds. Switching power supplies like the converter in the RV will delay the current being returned on the ground lead. This is just the way they work and is not a problem. But the house GFI sees this as problem and will trip the home GFI. There is nothing wrong here and this is normal operation for both the RV and the home.

Awesome. Thanks for the help

ScottBrownstein · 04-16-2016, 03:05 PM

Actually, the description is right with one exception. GFIs monitor the current in the hot and the current in the neutral and if they are different by even a small amount...they trip! His GFI just might be bad as they do not last for ever.

DDC · 04-16-2016, 04:27 PM

As I understand it you do not put twi GFI's on the same circuit it creates a fault.

Kenny kustom · 04-16-2016, 06:34 PM

My camper gets plugged into a gfi on the side of my garage, and hasn't ever tripped. Although, I will be putting a 30a plug in this summer.

2016 Sabre 36QBOK
2015 Ram 3500 CUMMINS

clr · 04-16-2016, 06:44 PM

Some GFI breakers do appear to be more forgiving than others. So sometimes with some RV's it will work, but with most newer RV's that I have seen it is a problem. It is best to feed the RV with a dedicated circuit that is not GFI controlled.

**Flybob** · 04-16-2016, 06:53 PM

One thing to check is the WH. If after the PDI, the electric element of the WH was left on and there was no water in the WH, the element would burn up. This will always cause a CGFI to trip if connected. May not be the problem, but it is worth a check before heading out on a trip.

bryanteddie0924 · 04-16-2016, 09:13 PM

If service is a 50 a service in RV, you need to make sure you are not running a 220 into it but you have to run 2 110's. You need to make sure the 50 a is 2-110 plug with seperate grounds. If you try to run a 220 in you may have blown the inverter.

HerveVR · 04-16-2016, 09:30 PM

Before having an RV outlet installed at home, better read these:

The 30-amp 120-volt 2 pole 3 wir

The 50-amp 120/240-volt 3 pole 4

dan-nickie · 04-17-2016, 03:13 PM

Quote:

Originally Posted by Chewie

Update, I have since switched him to an outlet inside his house, non-gfci, working on shore power. The instant the cords are connected to the gfci it trips. Even though all the breakers inside the motorhome are off. No blown fuses, breakers seem fine. I believe it's his house??

Around my house there are a number of outlets that are daisy chain from the bathroom CGI. Is that what's happening to him also? If so plug in where the refrigerator is. That should not be a CGI

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