GFCI Weirdness

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Roadturn

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Bend, Oregon USA
1971 Tramper Camper (canned ham)

If I run a regular outdoor heavy duty extension cord from the GFCI-guarded garage to my camper, the GFCI instantly trips.

If I use the cord that came with the camper (has the ground pin removed), it doesn't trip.

A local electrical expert says campers aren't grounded, so I can never plug it into a GFCI circuit.

I'm not comfortable using a cord with no ground pin, and I want to be able to plug in at campgrounds (just bought the camper and have yet to take it out).

So glad I found this forum.
 

Optimistic Paranoid

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GFCI circuits compare the current flowing through the hot wire to the current flowing back through the return wire, and if they don't match, to within a small fraction of an amp, shuts down the circuit.  It has nothing to do with whether your trailer is grounded, so your electrical 'expert' is clueless and should be ignored in the future. 

You've got a problem in your camper with current leaking someplace, and the previous owner butchered the camper cord so it wouldn't trip the GFCI in campgrounds.

If you plugged in to a non GFCI outlet with your 3 wire plug, there is a real danger that you could get a shock, possibly a fatal shock, from your trailer.

For more info on this see Mike Sokol's No Shock Zone:

http://noshockzone.org/
 

Arch Hoagland

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You need a new local electrical expert. RV's are grounded for sure. 

I have the same problem when plugging into the 110 outlet in front of my house while loading up.

Now what I do is go in the RV, turn off the two 50 amp input breakers and then go plug my extension cord into the 110 outlet on the front of my house.

Then I go back in the coach and reset the two 50 amp breakers and all is well.
 

Roadturn

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Bend, Oregon USA
Hmmm... I'll try the breaker trick.

This is a little 11-foot Tramper. It has two rubber tires. How is it grounded?

How do I check for a current leak? I've ordered the RV electrical manual.

Absolutely no desire to get shocked or die.
 

John From Detroit

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You ex-spurt told you the truth... Sort of.
Campers the neutral and ground are not supposed to be BONDED inside the camper. the bond is at teh "SERVICE ENTRANCE" which in your case is the fuse box back in the house.

I have 3 guesses..
one... Whomever wired your RV.. Did not know that.
Two: Ground/neutral short. this is not necessarly a hazard.
Three: Some times a divice inside the rv. OFTEN the converter. does not play nice with GFCI. Alas I can ot predict based on make and model if it will or not.

What makes it even more fun
Some play nice if batteries FULL  Some IF batteries LOW. Some always. Some never.
 

grashley

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Welcome to the Forum!

To expand a bit on Optimistic and John's comments:

The GFCI carefully measures the power going out on the hot wire and coming back on the neutral wire.  If they are not the same, it trips.  This difference could be because some of the return was on the ground wire (not dangerous, but will trip the GFCI) or because it is flowing through YOU to ground.

In house wiring, all white (neutral) and bare (ground) wires go to the same buss bar.  That is fine.
In a camper, the neutral and ground wires MUST be isolated on separate buss bars.  If they go to a common buss, it will trip the GFCI every time!
With an older camper, the neutral and ground may be on a common buss, due to changing codes for campers ?????  or a DIY repair by someone who knew no better.

Try the breaker fix first!  It is easy and free!
 

Roadturn

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Bend, Oregon USA
Got me, Preacher and all.

I'm attaching a photo of the breaker box. It's a home-wired setup for sure.

Funny thing is I have a selector that chooses between battery and a/c power. It's in the Off position when I plug in and the GCFI still trips.
 

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regval

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Your photo shows the neutral bus bar directly above the 20A breaker and the grounding bus bar to the left of the breaker. The neutral bus bar has white insulated wires attached.  The grounding bus has the bare copper wires attached but there is also ONE white insulated (possibly a neutral wire) also attached.  NOT GOOD.
With all power removed from camper, disconnect the white insulated wire from the ground bus bar and cap it off. Now retest to see of the GFCI still trips.  If not, then you've found the source of the problem.
 

Optimistic Paranoid

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Uh, there's not only a bare wire and a white wire going to that bus bar on the left, there's a BLACK wire going there, too.  WTH!?!
 

Roadturn

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Bend, Oregon USA
Thanks, Reg and OP. Should I remove all but the bare wire from the bus? I'll be able to get out there and do the work this afternoon.
 

Gary RV_Wizard

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A local electrical expert says campers aren't grounded, so I can never plug it into a GFCI circuit.
Your local expert clearly isn't, so I would ignore his advice.


It is evident in that photo that standard wire colors have not been followed, so I would first determine what those black & white wires on the ground bus bar actually do. If either is actually a neutral, they should be moved to the neutral bus bar.  A neutral wire on the ground bus will definitely cause the external GFCI to trip.
Funny thing is I have a selector that chooses between battery and a/c power. It's in the Off position when I plug in and the GCFI still trips.
That is a either a 12vdc power source switch or an inverter selector.  Most likely it chooses whether 12vdc power comes from the battery of from an AC/DC converter, but if the trailer has an inverter added on, it might be a shore vs inverter selector.
 

Optimistic Paranoid

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BTW, do you have one of those little 3 light outlet testers?  The one that shows whether the outlet was wired with the hot and neutral reversed, or the neutral and ground reversed, or several other problems?  What does that show when you plug it into the various outlets inside your trailer?

One of these things:

https://www.amazon.com/Receptacle-Tester-Klein-Tools-RT210/dp/B01AKX8L0M/ref=sr_1_7?s=lamps-light&ie=UTF8&qid=1537822105&sr=1-7&keywords=outlet+tester&dpID=31mlhkFf8YL&preST=_SY300_QL70_&dpSrc=srch
 

Roadturn

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Bend, Oregon USA
UPDATE: I disconnected the white wire from the bus bar and flipped the circuit breaker (onboard) off. Even with both of those things changed, plugging in still trips the GCFI. Go figure.
 

grashley

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I assume from the picture that the camper has ONE breaker.  The wiring  should be like this:

Power from shore power - Black - hot wire feeds breaker.  White wire to Neutral buss.  Ground to ground buss.

Black wire from breaker feeds black 120V coach wiring.  All 120V white wires from the coach go to the neutral buss.  All 120V ground wires from the coach go to the ground buss.

Make sure the neutral and ground buss are isolated!!  Use a meter to check continuity between the two buss bars.  It should be an open circuit!  If the two buss bars are not isolated, connect the white wires using wire nuts (and jumpers if needed) or similar connecting devise.  This WILL isolate them.

What brand / model converter do you have?
 

Roadturn

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Bend, Oregon USA
Thanks, guys.

The converter is ancient. Newmark 15 amp output. See the photo attached for a look at the whole setup.

 

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regval

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If you think the converter is the problem then you can just unplug it from the AC power outlet and retest the GFCI with the extension cord.
Edited: An additional comment - I agree that the converter is ancient (not as old am me, and I'm ancient !) - It's output (12V DC) is not regulated regarding demand and in some circumstances can overcharge your battery. Current converts are "smart" and provides charging current to your on-board battery based on demand.  If in your budget, I'd consider upgrading the converter to a newer style that provides both and AC load center (breakers for AC appliances or outlets) and a DC load center with fuses for devices that need 12V DC, isolating the DC circuits (lights, control panels in refrigerator, etc.)
 

Gary RV_Wizard

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Start with the $5 outlet tester (3 lights), but yes you need live power for that. Plug the RV to a non-GFCI outlet for that.  If you don't have one accessible, get one of those old adapters used to plug 3-pront plugs to 2-prong outlets. Don't hook the dangling wire of the adapter to anything and it should isolate the RV ground and inhibit any ground faults in the RV. If it doesn't, then you need to look for whatever external  ground path exists in the RV, e.g. a dangling wire on the RV that touches the real earth (ground).
 

regval

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Roadturn said:
Good point, Reg. Still blows. Trying to figure out how to use a GFCI tester, but thinking I'll need a live circuit to test.
Not sure what you mean about a GFCI tester, but if you want to prove your extension cord is OK, I'd just plug in something like a vacuum cleaner, space heater, etc. that has a three prong plug, which indicates an internal wiring where the appliance has a grounding attachment and the neutral wire is not attached to the chassis, and if the appliance works without tripping the GFCI breaker, then the cord is good.

I have some troubleshooting notes prepared based on your original photo, assuming you have no test equipment to use. It's a little long but I'll send it along if you want.

Good Luck,
Reggie
 

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