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richard5933

50-amp pedestal with GFCI

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Strange thing happened tonight, and I think that Custom Coach electrical work strikes again. Maybe you guys can confirm my theory.

So, here we are plugged into a new 50-amp pedestal at a campground. So new that it has a GFCI breaker on all the outlets - the 20-amp, the 30-amp, and even the 50-amp. Written right on the pedestal below each outlet. Don't think I've ever seen a 50-amp breaker protected by a GFCI, at least not yet.

Things were going great with no problems. Running our two monster CC a/c units and our water heater. Even fired up the induction cooker on 1500 watts with no problem. Then came the problem....

We have a small 120v exhaust fan over the cook top. I turned it on and instantly power was cut. At first I thought that maybe the little fan put us just over the limit on one of the legs, and that's what caused the breaker to snap. So, I tried again with only one a/c unit. Same thing happened. Every time that little fan is turned on, the 50-amp breaker at the pedestal snaps.

Here's my theory...

Custom Coach loved to interchange neutral and ground wires. They were not too particular about using only a hot and a ground if that's what was convenient. I haven't opened the fan up yet to test, but my hunch is that that instead of running a hot & neutral to the fan they ran only a hot and just used the chassis/ground for the other wire. Why? Because it's a lot easier to run a short jumper to the body (ground) than to run a neutral wire all the way to the panel. I've run into this in a few other circuits, and honestly thought I'd found them all. I've done lots of work trying to correct the neutral/ground bonding done by Custom Coach all over the place, and it wouldn't surprise me if this is one more example.

Would this have caused the GFCI to snap and go to fault state? This is my theory, that having the ground involved in carrying power instead of a neutral caused the GFCI to trigger. I don't have much experience working with GFCI outlets and/or breakers, so hopefully someone with more knowledge can confirm if this would cause the breaker to go to fault state.

Can't really do much testing right now, but when I get home I will. Don't want to open up the casing around the fan either, since there's no telling if I'll have problems putting things together at the camp site.

Really silly to even have the fan, since there is a MaxxAir fan just next to it. Maybe I'll just take the little thing out and cap the hole.

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Does it kick the breaker without the fan? Maybe you have a short in the fan. Have you tried the fan in another outlet?

Sorry these are what just popped onto my head. 

Herman 

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Yes it will 

Any bleed to ground will trip

Hot tubs use 50 and 60 amp GFIs 

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Try running the fan only on two wire extension cord directly to a 15 amp gfci circuit. If the fan doesn't trip that circuit, then your theory may well be correct. GFCI is not a load breaker, it is a means of checking for a difference of the load side against the neutral, ie., if the amp draw by law is 5 milliamp or more difference, the breaker will trip. Most manufacturers use 4 mills in order to be under the mandated specs.

(Any bleed to ground will trip), please note that the bleed is not from hot to ground, it is from hot to neutral, that is the black to white wires, not black to bare, or green in some circuits. Bare or green is the ground wire, and they must not be bonded to the chassis of the coach, what is bonded to the chassis of the coach is the negative circuit of your 12/24 volt batteries.

Edited by kaypsmith

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The exhaust fan is in the ceiling and hard wired - no way of plugging it in any other way. It's never been a problem before, but we've never been plugged into a site with GFCI on the 50-amp outlet.
 

The fan is identical to the small round Ventline 12v fans found in bathrooms, but this one is 120v. I don't think that they've made these for a while now.

 

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That was very informative and I also read the comments/replies!  Hope Richard reads it also! 

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I did. Still going to check wiring to confirm it's correct, but won't stress if it is and I still have problems with GFCI pedestals.

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