110 volt problem

We just purchased a 1995 Thor 36 Residency with an 110 v problem.  The seller will fix it at a shop, but I am wondering if anyone has ideas.  There are 4 GFI protected outlets on the circuit in question.  The start of the run is in the bathroom with the GFI (which I replaced) near as I can tell next is one above the range flush mounted, then one in the outside compartment at the back of the Dometic refer (the fridge plugs into it) & I think the end of the run is an outside duplex mounted on the side of the coach.  As soon as I power it up and set the GFI, it kicks.  I know I have it wired right cause my line side is hot, and load is not. With the exception of the GFI, they are all a surface mount type that I am not familiar with, I guess normal for RV use.  I am guessing it is the end of run one mounted outside that is the culprit, but it is silicone sealed on & don't want to pry it off outside, won't be able to re-seal it in sub-freezing weather.  All the other 110 circuits are fine. Anyone else had a similar issue?

As you said, the prime suspect is likely the outside one where water has gotten into the box. Start by making sure nothing is plugged in anywhere including the fridge and examine that one as well as it is pretty close to being 'outside'. You may have another one or two as well, perhaps in the storage areas underneath. You can have up to 8 other units connected to one GFCI, I believe.

I am inclined to support the outside outlet as the problem as well. Normally I would spspect something else but you have eliminated it (When I power it on it kicks off is the elimination statement).

Two options.. Get more violent with the outside outlet or  Add outlets one at a time .. You will need to remove wires from all the down-line outlets then see which wire is hot.. Connect that outlet. if the GFCI holds connect the other wire to that outlet and then see which wire is hot.. IF connecting the 2nd wire trips it. odds are that goes to the outside.. If you get lucky that will be the last outlet on the chain

Mark the next to the last and when you get a chance fix the outside one.

The seal, didn't woudl be my guess.

If you know the order the string of outlets is wired, from breaker to fourth outlet, try this.

Open the breaker, then:

Open (disconnect) the wires on the leaving side of the second outlet in the string.
- Close the breaker.
If the breaker trips the problem is between the breaker and the wires you just opened.
- Open the wires entering the second outlet and reset the breaker.
If the breaker trips the problem is the first outlet or the wiring between the first and second outlet. If the breaker doesn't trip, the problem is at the second outlet.

If the breaker doesn't trip when you opened the leaving side of the second outlet as above, then put the wires back on the second outlet.

Next, with the breaker open:
- Open the wires on the leaving side of the third outlet and reset the breaker.
If the breaker trips the problem is at the third outlet or the wiring between the second and third outlet.

- Open he wires on the entering side of the third outlet and reset the breaker.
If the breaker trips the problem is the wiring between the second and third outlet. If the breaker doesn't trip, the problem is at the third outlet.

If the breaker doesn't trip when you open the leaving side of the third outlet as above, then put the wires back on the third outlet.

Next, with the breaker open:
- Open the wires entering the fourth outlet and reset the breaker.
If the breaker trips the problem is in the wiring between the third and fourth outlet.
If the breaker doesn't trip the problem is at the fourth outlet.

Actually, since your fourth outlet is outside and you don't want to open it if not necessary, I would start the testing by opening the wires on the leaving side of the third outlet. If the breaker trips when being reset the problem is between the breaker and the wires just opened. But, if the breaker doesn't trip the problem is at the fourth outlet or the wiring between the third and fourth outlet. You could simply leave these wires unhooked, reset the breaker and have full use of the inside outlets while you further investigate the outside wiring and outlet.

I think I might just try a hair dryer om the outside outlet to see if I could dry it out.

Ernie

Quillback gave the optimal procedure for troubleshooting, but sometimes you get lucky and can short circuit (pun intended) the process. Statistically, the most likely candidates are the outside outlet (water) and the fridge electric heater element. Unplug the fridge (or force LP gas mode) and see if that avoids the problem. If not, work the outside box for a bit as others have already suggested. If neither of those quickly isolates the problem, go to Quillback's more rigorous procedure to find where the problem lies.

You probably know this, but the problem is a short to ground somewhere, most likely a high-resistance short. If it was a direct hot-to-ground short, the breaker would probably trip before the GFCI opens.

Certainly nothing very rigorous about unhooking two wires on the third outlet and tripping the breaker back on to prove if the problem is that outside outlet or not. Sure beats ripping the outside outlet apart and all the wiring without knowing what you are looking for.

BTW, the first test of the "rigorous" procedure, assuming he would like to go that way, eliminates both the refer and other outside outlet.

Thanks for all the great input!  I think Quillback's method is probably the best for trouble shooting this.  I know it is not the fridge electric heater element because if I plug the fridge into an outside power source, it works.  how much of a mess will I make if I pop the back off of one of those surface mount outlets?  I have never messed with any like that, and all you can see is the wire going in.  Don't want to open something up that I can't get back together (never done that before i my life ;D)

Rigorous means "thorough", not "difficult". 

rockman said:

I know it is not the fridge electric heater element because if I plug the fridge into an outside power source, it works.

Click to expand...

You ruled out the element but it could be a bad receptacle your fridge is plugged into. Unlikely though but it could be. Just keep that in mind.

rockman said:

Thanks for all the great input!  I think Quillback's method is probably the best for trouble shooting this.  I know it is not the fridge electric heater element because if I plug the fridge into an outside power source, it works.

Click to expand...

Not necessarily.  The heating element could have a HIGH RESISTANCE leakage to ground - enough to trip a GFI, not enough to affect the element's operation on a non-GFI circuit.  We're talking leakage to ground in the range of 4 to 6 milliamps to trip a GFI.

I'd do the easiest test first - unplug the fridge and see if the GFI still trips.  If it does, then proceed with dismantling the circuit.

This doesn't help the OP, but I thought that if you had a GFI with outlets following it, that they were all protected.  Mn code says in a Garage setting only the 1st box after the breaker needs a GFI and all boxes on that circuit are then protected.

If that is the case, why does the OP have 4 GFIs on the same circuit?

He doesn't Keven, he has 4 outlets, the first one (bathroom) has the GFI. The others are RV outlets downstream from and protected by the one GFI outlet in the bathroom.

OP said: "There are 4 GFI protected outlets on the circuit in question.  The start of the run is in the bathroom with the GFI (which I replaced) near as I can tell next is one (speaking about the outlets in the line) above the range flush mounted, then one in the outside compartment......"

Ken

Right, misread that.

Quillback 424 said:

Certainly nothing very rigorous about unhooking two wires on the third outlet and tripping the breaker back on to prove if the problem is that outside outlet or not. .

Click to expand...

Simple Definition of rigorous

1 very strict and demanding
2 done carefully and with a lot of attention to detail
3 difficult to endure because of extreme conditions

kjansen said:

Right, misread that.

Click to expand...

I've never done that........ :

Ken

I'm all for DIY projects to save money, but the seller has committed to repair the problem. If you break something else poking around, that offer just might come off the table.

HappyWanderer said:

I'm all for DIY projects to save money, but the seller has committed to repair the problem. If you break something else poking around, that offer just might come off the table.

Click to expand...

You are exactly right, that is also what my wife has been telling me.  I think I will let a professional fix it. Thanks for all the input everyone, Happy New Year!!

Ernie n Tara said:

I think I might just try a hair dryer om the outside outlet to see if I could dry it out.

Ernie

Click to expand...

Fair plan but you'd have to open the outlet to properly dry it.. I think I'd start by opening the outlet,, A sharp knife (Exacto) may be able to slide the sealant so you can pull the cover off.