# Aarghh!!!! I Hate Electrical Gremlins!



## PDX_Doug (Nov 16, 2004)

Man, This is not what I needed less than 24 hours before departing for the Fall Rally! This afternoon, I brought the trailer home from the storage yard to pack up for the weekend. Run the electrical cord out from the garage. Plug the trailer pigtail (can it be a pig tail, if it is 15' long?) into the extension cord, and pop goes the GFI the extension cord is plugged into at the house end. Thats the quick and dirty. Here are the specifics.

1. We have a 15 amp circuit in the garage. The one and only duplex outlet in the garage for this circuit is a GFI. This same circuit services the bathrooms in the house. Nothing else is plugged into any of the other outlets on the circuit during this time.

2. We have always used this circuit to power the trailer when it is home, and have never had an issue (even one day in August when we ran the A/C all day).

3. I run a 12 gauge extension cord to the trailer (actually, two 25 footers to reach far enough).

4. Now, as soon as the the prongs of the plug (at either) end, make contact with thier respective outlet, the GFI blows (Not the 15A breaker in the breaker box, just the GFI).

Diagnosis to this point.

1. I turned off all the breakers in the trailer (at the inverter below the fridge), and opened the battery cutoff switch. Still blows.

2. I substituted different extension cords. Still blows.

3. I moved the extension cord away from the 15A GFI circuit, and plugged it into a duplex on another (non-GFI protected) circuit in the house. Everything works! I can bring all breakers in the trailer back on line, reconnect the batteries, run the A/C and microwave simultaneously... IT ALL WORKS!

This would indicate to me, that the GFI outlet is probably bad, except...

4. I can not get the GFI to trip with any other load. I have tried 1500 watt hairdryers and space heaters, my radial arm saw (which takes a big surge when it starts up), drill press, anything. The GFI will not trip!

5. Plug the trailer back into the GFI, and... POP!

So here is the mystery...

If the trailer works fine on a normal circuit, but trips the GFI on that circuit, you would think the GFI is bad. You would also expect other loads to trip it also though, but they don't.

If the trailer blows the the GFI everytime it is plugged in, and nothing else does, you would think there is a problem with the trailer. But the trailer works fine when plugged into another circuit.

Remember that this is the same setup we have been using since we bought the trailer.

The main issue in my mind - at this time - is, what do we do about this weekend. If this is an indication that we have a major electrical problem in the trailer, it calls the wisdom of the whole trip into question. If it is the GFI circuit, I can deal with that later.

Anybody have any ideas?

Happy Trails,
Doug


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## Thor (Apr 7, 2004)

This is a good one.

I'm no electrical expert - Enjoy the rally







I do not plug my TT into a GFI

GFI's trip when there is a path to ground. GFI's are sometime hooked to together on the same circuit. Have you tried plugging in your TT into another GFI outlet? Try a single extention cord, maybe the connnection is creating a ground. Check your other GFI for any problems. Is your TT grounded some how? Does your extention cord have 3 prongs?

Good Luck - and let so know. I am going to plug my TT into a GFI outlet to see what happens.

Thor


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## LarryTheOutback (Jun 15, 2005)

PDX_Doug said:


> If the trailer blows the the GFI everytime it is plugged in, and nothing else does, you would think there is a problem with the trailer. But the trailer works fine when plugged into another circuit.[snapback]56829[/snapback]​


But the other circuit you are testing with is not GFCI protected, if I read your posting correctly. You may very well have a path to ground in the trailer somewhere. Not good. See How Stuff Works for a description of how a GFCI differs from a circuit breaker.

That said, you'd be better off testing it on a second GFCI circuit if you have one (there will likely be one at the campsite  BTW, I always plug Larry into a GFCI and it never trips.

Worse case you can spend the weekend on the battery (maybe recharge when nobody is in the trailer).

Cancelling the trip is not an option!


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## PDX_Doug (Nov 16, 2004)

Thor,

We only have the one GFI circuit in the house (Bathrooms and garage). I'll see if I can reach another outlet on that circuit.

All extension cords in use are 3-prong into a 3-prong outlet.

If extension cord were creating a ground, wouldn't it trip the breaker on the other circuit?


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## CamperAndy (Aug 26, 2004)

Doug - Remove the cover from the outside outlet on the trailer. I think you may find it has water in it. One of the reasons a GFI trips is there is a current flow in the ground leg. This may not be enough current to trip a normal breaker but it only takes a little be to trip a GFI. Also make sure your GFI in the trailer is reset in the bathroom.


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## HootBob (Apr 26, 2004)

MAn I glad Andy is here
I would have forgot about that outside outlet








Let us know how you make out Doug.

Don


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## j1mfrog (Jun 6, 2004)

Try unplugging everything (including the supply) and checking resistance from your main busses to ground inside the breaker panel of the TT to verify a short to ground.

You could also leave everything plugged in with the trailer on the circuit that works and check voltage from the trailer frame (ground) to actual earth ground. If you've got voltage on the frame, you've got a problem.

I once used an home fixed extension cord with the leads swapped and ended up energizing the trailer frame. Not a very safe condition. A short to ground from your hot bus could do the same thing.


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## GlenninTexas (Aug 11, 2004)

I had a similar problem with a 50amp GFI circuit for my SPA, turns out a lock washer inside oner of the motors broke in half and fell across the supply wire leads.

Go into your circuit box in the TT and turn off all circuits.
Check all wire connections within th ebox to insure they are tight.
Plug the TT power source into your GFI. 
If the GFI trips, the problem is outbound of the circuit box, e.g. between the GFI circuit and the TT circuit box.

If the GFI remains on, then engage one circuit at a time within the TT until you find the one that makes it trip.

GFCI switches do tend to weaken over time, so don't rule that out.

You might also borrow a neighbors garage outlet to test on a different GFI circuit.

Good Luck, Glenn


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## PDX_Doug (Nov 16, 2004)

Thanks for the replies, guys!

I will check these things out when I get home.

j1mfrog: Just to verify. When checking resistance from the buses to ground, I should be seeing zero resistance if all is well?

Also, when you say buses to ground, are you talking about grounding to the trailer frame, or to the ground wire in the supply line?

Happy Trails,
Doug


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## j1mfrog (Jun 6, 2004)

PDX_Doug said:


> Thanks for the replies, guys!
> 
> I will check these things out when I get home.
> 
> ...


Now I've got to be careful here because I know just enough to be dangerous. When checking resistance from the busses to ground, the one you are worried about is the hot bus and it's resistance to ground should be infinite (high), not zero. If you find it a zero or a low ohm reading, you've got a short. The neutral bus and ground are sometimes tied together so you may find that one at zero ohms anyway.

Very Important: Don't check resistance with power supplied to the trailer. Disconnect power supply first.

The trailer frame and the ground wire in the supply line should be electrically the same point, so either one.

A quicker check would be to check voltages to earth ground (that's the ground your house uses, usually through a copper rod pounded into the ground). When you check these you should see 120v from the hot bus to earth ground, and zero or low volts from the neutral bus and trailer ground (trailer frame) to earth ground.

Disclaimer: I am not electrician, just someone who knows what 120vac feels like, and be careful because it doesn't feel good.

BTW, I have checked the voltages on these busses to ground by pounding a copper stake (some old 1/2" pipe) into the ground right next to my outside outlet and checking the outlet voltages to the stake. This is probably not approved by the Electricians Association of America, but it worked and helped me figure out where my problem was. You should only see voltage (~120vac) on the hot outlet.


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## PDX_Doug (Nov 16, 2004)

Jim,

Thanks for the clarification. And you are right, resistence should be infinite (just goes to show, you really shouldn't be playing around this stuff when you are suffering from a lack of sleep!).









And no, 120VAC does not feel good. But it sures does get your attention!









Happy Trails,
Doug


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## Dark Green Dmax (Aug 2, 2005)

How bout checking your ground lugs on your cords. ....any normal breaker doesn't care if the ground is hooked up,....but a GFI is another story. Could a lug be broken in one of your cords but still hanging on inside the insulation? When i run into problems...i check out the most mundane overlooked solutions first....then work my way to the harder fixes next. Usually the simpliset most overlooked problem is the anwser. A cord with a damaged neutral will still work if the ground is intact (but not on a GFI) this is NOT the way it should work. You can get a deadly buzz from it!


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## DANJOGAVINMO (Apr 17, 2004)

dark green is on to something here. Doug stated he turned off all breakers and threw batt switch and it still blows (this fact would also nullify camperandy's suggestion of water in outside outback outlet). So something must be wrong with either the camper elec cord or any connections up to the converter.

good luck doug


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## Woody (Oct 1, 2005)

I'll be waiting to hear the resolution to this. I have the same problem with my TT. I spoke to a repair facility and he said to check and make sure the wires to the GFI are hooked right (black/white). Also the adapter may be the culprit. Basiclly he said if I had no problems at the campgroung with 30 amps, not to worry!

I'm going to ask my brother-in-law to help me put in 30 amps in the garage so I can hook up with no problem.

Woody


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## dmbcfd (Sep 8, 2004)

Doug,

At the trailer end of the shore cord, there is a junction box. With the shore cord UNPLUGGED, check the condition of the splices in that box. A wire nut could have come loose, or it may be wet. Mine is located under the dinette bench with the city water, tank fill, and pump. Lots of possibilities for small leaks.

By the way, I am an electrician. You have done a great job troubleshooting, so far. I think your problem is in either the cord, its connections, or the cable between the converter and the cord.

Good luck,

Steve


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## PDX_Doug (Nov 16, 2004)

Again guys, Thanks for all the input on this! I really do appreciate it!

Dmax:
Ground lug may be a possibility. I did swap out the extension cords between the GFI and the shore power cord, and it did not help. But I suppose it could be the shore power. That 30A adapter is awfully hard to get on and off, so I could see how that could be bad.

Danny:
My initial fear is that it was something between the shore power cord and the breaker box/inverter (fear because that could be a real P.I.T.A. to find!

Woody:
As it happens, we had our Fall Rally this weekend, and the trailer worked fine on the 30A circuit. I do not know that I would agree with your service department that everything is fine if it works on the 30A, as the 30A is not GFI protected. Maybe we could get an expert opinion on this from...

dmbcfd:
Steve, I will check those connections. Mine is under the sofa, and nowhere near any water source, so I doubt that will be a problem. But the connections could be bad. That would be a new one for Keystone, eh?







Would you mind if I PM or e-mail you as this progesses?

Thanks again guys,
Doug


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