GFI trips at home when trailer plugged in

[wgriswold]

Today I plugged my trailer in at home in preparation for a trip, to charge the batteries. The GFI in the garage was tripped.

I turned off all the breakers for 120V in the trailer and it still tripped. The only thing I had done recently was to take apart the 30 amp plug because it didn't seem right where it entered the plug. I could see the three wires and that didn't seem right. I took it apart and everything looks fine. I can't see any way the plug could could cause the GFI to trip, but what do I know.

I plan to replace the plug tomorrow and see what happens. Any other ideas?

[camperpaul]

robber6 wrote:

I know that on boats twist on connectors are not allowed by code because they can fail due to vibration and banging around. What do you all do with the connections on trailers?

Those twist on connectors (wire nuts) don't work very well with the finely stranded wire used in the power cords, so I'm not surprised that the problem was where you found it.

The wire connectors of choice for that application are crimp 'butt splices' which must be installed with the correct tool.

[robber6]

First of all, thanks for your help. Immediately after finding the problem we left on an eight day trip with our grown kids and grand-kids. Consequently, the long delay in reporting back.

After checking everything that was suggested I looked at the junction box where the cord ties into the trailer electrical system. The neutral connection had melted the twist on connecter and the insulation back about 1". I cut back to good wire and connected it with another twist on connecter and all was well. I also taped the three connecters so they could not unwind. I assume that the neutral connector unwound and the connection got hot and ultimately failed.

I know that on boats twist on connectors are not allowed by code because they can fail due to vibration and banging around. What do you all do with the connections on trailers?

Edit: I used my son's username; this message actually came from the OP, wgriswold

[mchero]

I have a 93 Pace Arrow with 50 amp service. When I was at a campground with a 20AMP GFI outlet it kept tripping the GFI outlet on the pedestal. I turned off ALL breakers & still was tripping the GFI!

I opened the Xfer switch panel where the shore power cord enters the Xfer switch. I started disconnecting loads on the shore power cable until the GIF stopped tripping.

I found that a 1/2 wave rectifier was supplying DC voltage to a DC cut-out relay. This relay prevents the Inverter from powering the forward AC when on Inverter power.

Apparently, the capacitor in this 1/2 wave rectifier was tripping the GFI, meaning a SMALL amount of voltage was charging the capacitor when the coach s 1st plugged in tripping the GFI.

I modified the 1/2 wave rectifier to a full wave rectifier and removed the capacitor and my tripping GFI was no more! Don't know why a DC relay was used! AC voltage tends to overheat DC relays, thus the reason for the rectifier.

Hope this heps the OP & others as well.

[vermilye]

Here is a previous post of mine describing how to find GFCI faults.

[time2roll]

Just disconnect the cord from where it connects in the RV. That will rule the cord good or bad. Then move down the line to the breaker panel.

If it appears to be in the breaker panel... start by disconnecting the fridge, then water heater, then converter.
Good luck.

[wgriswold]

I must have a neutral to ground fault as I have eliminated everything else. I will check for shorts with my volt meter and for tight connections at the trailer end of the cord and at the breakers. If that does not work, it is off to the electrician. Thanks for the help and I will let you know the outcome.

[aruba5er]

Some GFCI's will trip Neutral to Ground ( know that Square D breakers do for sure) and so if you have one shutting off the breaker would not solve anything. Buy and learn to use a VOM= VOLT_OHM_METER. They sell from $2.98 up and sometime they give them away at Harbor Freight. That way you can check if you have any shorts in the cord, see if you have any shorts to frame or if you do have a good ground to the frame. A meter is a necessity. Looking at things doesn"t always produce results.

[vermilye]

wgriswold wrote:
Wouldn't turning off the breakers in the trailer turn off the appliances?

While turning off the breakers will prevent a hot to ground fault from tripping a GFCI, it does nothing to prevent a neutral to ground fault from causing the problem. Modern GFCIs have additional circuity to detect neutral/ground faults. A neutral to ground fault is difficult to find since turning off the breakers has no effect. The only way you can find the fault is by disconnecting the individual circuit neutrals at the neutral buss one at a time.

As to the OP's question - unless he had a fault occur at the same time he rewired the plug, I suspect a problem with the rewiring - I'd look for loose strands, etc. One other possibility is a bad adapter going from the RV connector to the household receptacle.

Finally, you can string as many GFCIs as you want. Like others, I often plug my trailer (which has 2 GFCIs) into GFCI receptacles with no problems. They do require power to reset. If both the RV & the household or campground GFCI trip, you have to reset the household one first.

[joebedford]

donn0128 wrote:
You cannot plug a trailer into another GFCI. They do not play nice with the GFCI that is already in your trailer.

I do it all the time. No problems whatsoever.

Now if I start the generator in the trailer, THAT will trip the house GFCI.

[wgriswold]

smkettner wrote:

wgriswold wrote:
I plan to replace the plug tomorrow and see what happens. Any other ideas?

Polarity must be correct. No stray strands of wire.

http://www.myrv.us/electric/
(click 30a service, top left)

Great website, thanks. The screws in the plug are a little corroded. I wonder if corrosion on the screw connection can lead to a GFI problem. I guess I will find out tomorrow.

[Wayne_Dohnal]

You cannot plug a trailer into another GFCI. They do not play nice with the GFCI that is already in your trailer.

If GFCIs didn't play nicely together you could never use a newer hair dryer in the bathroom of a newer home. My motorhome does not trip a GFCI, and an RV that does has something wrong with it. If you're using a 15(or 20)-to-30 amp adapter, suspect that first. They seems to be the single biggest culprit in GFCI trips. For further troubleshooting I suggest following this post: GFCI troubleshooting .

[Harvey51]

I would be checking that cord with an ohmmeter. Disconnect it from power! With the breakers tripped, there should be infinite resistance between the hot conductors and ground. A GFI is supposed to trip at about 2 mA corresponding to a resistance of 60 kOhms on 120 V so you will likely see less than that. Now is it the cord or something in the breaker box? The only way to find out is to disconnect the cord at the breaker box. Is the less than 60 k resistance on the cord or is it on the terminals it was connected to? If in the cord and you can disconnect a wire at the plug end, you can tell which wire it is and whether it is the plug or the cord itself.

[time2roll]

wgriswold wrote:
I plan to replace the plug tomorrow and see what happens. Any other ideas?

Polarity must be correct. No stray strands of wire.

http://www.myrv.us/electric/
(click 30a service, top left)

[OnaQuest]

donn0128 wrote:

ScottG wrote:

donn0128 wrote:
You cannot plug a trailer into another GFCI. They do not play nice with the GFCI that is already in your trailer.

I'm sorry but this isn't accurate. You can daisy chain a dozen GFCI's and they wont trip. So yes, you can plug a trailer into a GFCI - or should be able to if all is right.
The problem is you have a ground fault someplace - ground is touching hot. The most common causes are the heater element in your fridge, which can work fine but has contacted chassis ground (repl it). Other causes are the water heater or a wet external outlet.
You can isolate it by unplugging each item one at a time and trying the GFCI again.
You want to fix this because it can be a very dangerous condition.

That depends on whether they are in series or parallel. The OP has one feeding the RV and another in the RV. That will not allow them to play nice together.

Repeating your statement does not make it true. You can have GFCI circuits and breakers in your RV and still plug it into a GFCI outlet. I do it all the time.