GFCI Troubleshooting?

[JimM68]

Monaco Knight 40skq, tripping one of the GFCI's.

The circuit is one of the inverter circuits. It has 2 load cables attached. One of them made the old GFCI buzz and blow.

New GFCI don't buzz, still blows, after 10 or 15 minutes.

The effected load powers:
1 outlet in road side front slide
2 under cabinet outlets in kitchen (curb) slide
TV outlet (in center of coach in this floor plan)
Bathroom
And the basement outlet.
Edit: icemaker too.

Just FYI, the load that isn't blowing goes to the BR TV, and the dash and overhead outlets.

How in the world does one troubleshoot these things?
I do have and know my way around a meter...
According to my Navy training, I want to split the circuit into pieces, find the bad piece, and fix it.
But where is the junction? I have 1 romex cable that goes 5 places, and each of those places only has 1 cable going into it!

I am measuring about 200k ohms between neutral and ground on the bad load...
Just a question of finding it.

[JimM68]

Yup. Icemaker. Plugged it into the other (non gfci) outlet back there for now. Weverything else back together and all working fine.

[crasster]

Open up the outside plug on the circuit. See if it has corrosion or water damage. You can go around and check other outlets too, but if any seals were bad on the outer plug that could definitely cause it to blow.

[JimM68]

bullydogs1 wrote:
This is one you are going to have to troubleshoot one at a time..why do I think it is the icemaker?...pull out plug to icemaker...and see what happens...this happened to me with one GFI tripping and it turned out to be a bad charger for a phone...remove charger and no more tripping...

Yup. It came to me while I was waking up this morning. Still have to test and prove it. The icemaker. It's still plugged in, the last thing on this line that is. There is lots of "stray ice" up behind it. It's working really well since the last time I fixed the fridge...

Why does it always come back to the damned dometic fridge?

[bullydogs1]

This is one you are going to have to troubleshoot one at a time..why do I think it is the icemaker?...pull out plug to icemaker...and see what happens...this happened to me with one GFI tripping and it turned out to be a bad charger for a phone...remove charger and no more tripping...

[malexander]

If we lived closer together, I'd be glad to help you out.
This is all I do. I work on, and do service work on mobile/modular homes. These things come from the factories with problems a lot of the time. OR if the maintenance guys have been there trying to figure something out (usually screwed it up) and don't tell you what they've done.

[JimM68]

Harvard wrote:
You may have moisture between Hot and Ground providing a capacitive coupling as opposed to a resistive "short" issue. A short would trip immediately as opposed to being a delay.

Possible, even likely.

The basement outlet, which is on the affected circuit, has been known to cause gfci tripping if that area got moist. I did pull it out and open it up, it all looks OK.
I did pump and dump today, but nothing over there got wet.

Question becomes, how to test it?
Or how to isolate it?
I have a single GFCI in the hallway. It has 2 romex cables connected to the load side. One of them is causing the problem, and I know which one it is.
But that line feeds a bunch of stuff, in 2 different slideouts, inside the coach, and in the basement.

[Harvard]

You may have moisture between Hot and Ground providing a capacitive coupling as opposed to a resistive "short" issue. A short would trip immediately as opposed to being a delay.



On edit: I should have said a "higher then normal" capacitive coupling as all AC wires in parallel runs have a low level of capacitive coupling between them. By adding moisture to the equation the dielectric between the wires will change from air at 1 to water at as much as 80.

[rgatijnet1]

Perhaps the amplifier for the crank up antenna is still powered. I still think that you have a frayed or loose wire somewhere that will require you to pull out each outlet and look at the wires. If the factory just pushed the wires in to the back of the outlet, instead of wrapping them around the screw posts, I would rewire each outlet when I have it out.

[JimM68]

I'm still working that.
The AC layout diagram I have is next to worthless.

I'm showing low resistance white to black on the affected load, but can't for the life of me figure out what is still plugged in.

In an ideal world, I'd like to find where all this is connected together, there must be a box somewhere, perhaps in the basement?

[rgatijnet1]

Have you removed everything that is plugged in to any outlets fed from the GFI? If you have then you may have to pull each one and look for any loose/frayed wires in each outlet until you find the one that is causing the problem. Remember what a GFI circuit breaker does. It trips at the slightest leak of power to ground so you are not looking for a dead short but more likely a slightly frayed wire that is just barely touching from time to time.
Make sure that you find ALL outlets that lose power when the GFI trips.
Also look for any outlets that may have overheated at one time from a portable electric heater.