My electrical problem involving a GFCI

patrick1945 · May 3, 2010

Each year I plug my 3055 in to a 15 amp GFCI located on the outside of my shop. 15 amps keep the battery charged and we can use the FW as an extra bedroom (without air conditioning) with a small fan and radio.

This has worked well until returning home this spring. The only thing THAT I KNOW OF outside the trailer that might cause the GFCI receptacle to trip is that my bride mistakenly drove over the 50 amp wire on our gravel drive way.

In the process of trying to isolate the problem I plugged in to another circuit with a GFCI and it was also tripped. When I plug the FW in to a different circuit without a GFCI there is no issue and all works inside.

These are my questions: 1) is it possible that the 50 amp wire was damaged but only a GFCI plug will pick it up. Understand that I replaced the old GFCI receptacle with a new one. 2) can I replace the GFCI receptacle with a standard one? 3) if I do this what problem might I encounter when I pull into an RV site next November and plug into a 50 amp outlet? 4) and how can I test this 50 amp plug without buying a new one?

there I did it - I typed GFCI 10 times..

JohnDar · May 3, 2010

Did you check your cord for continuity, like I suggested a week ago?

"Easy enough to check. Connect your VOM to both ends, set on Ohms. Have your assistant wiggle and manipulate the cord to see it you lose continuity. Do this for all four terminals. If the cord was laying on a hard surface when it was used for a speed bump, it may have damaged it internally. "

Since the GFCI's you tried trip and the standard outlet does not, it does sound like there may be a short to ground within the cord. Moving the cord around may even open and close the short. A standard outlet would not pick it up and you won't trip a circuit breaker until you exceed it's capacity.

You might also try connecting a 30A cord (if you have one) or borrow another 50A cord to see if the problem persists.

cookie · May 3, 2010

Hmm, first let me state my qualifications........I have none. The GFCI is just what it says it is, Ground Fault Circuit Interupter. Could you replace the GFCI with a standard receptacle, sure. But code requires anything outside to be protected by a GFCI. So that is not safe or recomended. Kinda like putting a penny in a fuse slot. It'll work, but it aint right, nor is it safe.
When the GFCI trips it's telling you something is wrong. The shore cord your DW ran over could be the problem. Maybe you could borrow one from someone and check it out. Or use your meter to check the cable for shorts.
It's also possible that you have a problem with ground in your coach. Have you checked wiring at the Marinco 50 amp plug? Or checked the wiring at the breaker panel?
Or maybe you have moisture somewhere in an enclosure. Moisture is what the GFCI is most particular about. That's why they are required anywhere water is or can be.
So anyway, I would look for a ground problem.
And remember, I have no qualifications, these are just my thoughts. And I only had to type GFCI only 6 times.

Peace
Dave

DXprowler · May 3, 2010

I find it hard to believe that driving over a 50 Amp cable would cause a short but I guess anything can happen! To test for that do a continuity check with a volt meter by checking the individual lines of the cable via the male and female plugs. Roll the cable up and connect an alligator clip to the male ground and then probe all the female lines. Do this for all four and if any show continuity where it shouldn't, example; ground and neutral, then you have a short. If that's OK then I would check the GFCI.

On an aside I discovered that if you don't twist the twist lock of the 50 Amp connector my EMS will show a ground fault and I won't get any power to the trailer unless I over ride the EMS. But it I'm dog-boning to 15 Amp, no issue!

jolar3329 · May 3, 2010

My 2009 Big Horn 3670 with 2 batteries has had the same problem since it was new. I returned it to the dealer once to fix the problem. When I got home it still had the problem. I plan to remove the GFI and install a regular outlet. If you open the breaker to the ac/dc converter the GFI won't pop. I don't know what the problem is.

branson4020 · May 3, 2010

Patrick,

In a previous thread where you asked for help diagnosing your problem, someone (rollinghome?) outlined a very detailed and comprehensive trouble shooting procedure that would determine just exactly where your problem lies, and yes, it is most certainly a neutral-ground short. Have you done this trouble shooting?

branson4020 · May 3, 2010

Jolar3329,

Have you checked for a miswired outlet (the one your converter is plugged into?). It sounds like swapped neutral/ground or a neutral-ground short.

patrick1945 · May 3, 2010

I did check out the cord as you suggested and I could not find a problem. Separately I had a neighbor with a different multi-meter check it out and he too could not find a problem. Once again all works ok on the same curcuit but on a non-GFCI plug. Evidently the GFCI does not protect the other plugs because it is at the end. I cannot understand why it worked last year but not this year.

I am thinking about replacing the GCFI with a standard plug. The plug outside is covered and 4 feet off the ground. I will go to a dealer tomorrow to have the 50 amp cord checked out by a pro.

JohnDar said:
Did you check your cord for continuity, like I suggested a week ago?

"Easy enough to check. Connect your VOM to both ends, set on Ohms. Have your assistant wiggle and manipulate the cord to see it you lose continuity. Do this for all four terminals. If the cord was laying on a hard surface when it was used for a speed bump, it may have damaged it internally. "

Since the GFCI's you tried trip and the standard outlet does not, it does sound like there may be a short to ground within the cord. Moving the cord around may even open and close the short. A standard outlet would not pick it up and you won't trip a circuit breaker until you exceed it's capacity.

You might also try connecting a 30A cord (if you have one) or borrow another 50A cord to see if the problem persists.

DXprowler · May 3, 2010

What about the adapters to 15 Amp, have you checked those?

dreamer · May 3, 2010

I had that issue on a previous trailer. Spent too much time looking for a short to ground and never found one. I read on an other post an RV technician said to replace the hot water tank anode. Did not make sense to me but as a last resort did replace it[It was 50% corroded]. My problem was solved. Would suggest shutting of the hot water tank and pull out the annode and try plugging your unit in.
Hope this works for you

JohnDar · May 3, 2010

patrick1945 said:
I did check out the cord as you suggested and I could not find a problem. Separately I had a neighbor with a different multi-meter check it out and he too could not find a problem. Once again all works ok on the same curcuit but on a non-GFCI plug. Evidently the GFCI does not protect the other plugs because it is at the end. I cannot understand why it worked last year but not this year.

I am thinking about replacing the GCFI with a standard plug. The plug outside is covered and 4 feet off the ground. I will go to a dealer tomorrow to have the 50 amp cord checked out by a pro.

I wasn't sure what you'd done since this seemed to be a repeat of your earlier post. If there's nothing wrong with the 50A cord, and the GFCI outlet functions with something other than your trailer plugged into it (does it?), then it does sound like something in the trailer.

As for changing the outdoor outlet from a GFCI to a standard one, the "legality" may depend on your local codes and when your house was built. In my house, the outlets on the porch and the rear deck are enclosed in outdoor covered boxes and are not GFCI. House was built in 1994. Outlets inside, near water, are GFCI.

Willym · May 3, 2010

Checking the cord with a multimeter for "shorts" may not tell you if you current leakage to ground. If you had a significant short you'll trip any breaker on overcurrent. GFCI's are very sensitive and will trip when they detect a small mismatch between outgoing and returning currents. They are designed to prevent people from being killed when their body becomes the path to ground. Only a small current is required to stop the heart, thus GFCI's will trip on just milliamps (as little as 5mA) of mismatch. A resistance of 24000 Ohms will allow this current, but will not show up as "short" on a continuity tester.

I don't think that the OP has definitively stated that he has completed the process of elimination, as someone suggested earlier. That is, open all trailer CB's, unplug the trailer, unplug the cord at the GFCI, then disconnect any dogbones. Next plug in the dogbone, connect the cord, then plug the cord into the trailer, and then start closing CB's. The point at where the GFCI trips, will tell you where the fault is.

I don't recommend replacing the GFCI with an ordinary outlet. they are there to protect you and your family. GFCI's do go bad sometimes, but they are very cheap to replace.

patrick1945 · May 4, 2010

what is a dog bone?

Willym said:
Checking the cord with a multimeter for "shorts" may not tell you if you current leakage to ground. If you had a significant short you'll trip any breaker on overcurrent. GFCI's are very sensitive and will trip when they detect a small mismatch between outgoing and returning currents. They are designed to prevent people from being killed when their body becomes the path to ground. Only a small current is required to stop the heart, thus GFCI's will trip on just milliamps (as little as 5mA) of mismatch. A resistance of 24000 Ohms will allow this current, but will not show up as "short" on a continuity tester.

I don't think that the OP has definitively stated that he has completed the process of elimination, as someone suggested earlier. That is, open all trailer CB's, unplug the trailer, unplug the cord at the GFCI, then disconnect any dogbones. Next plug in the dogbone, connect the cord, then plug the cord into the trailer, and then start closing CB's. The point at where the GFCI trips, will tell you where the fault is.

I don't recommend replacing the GFCI with an ordinary outlet. they are there to protect you and your family. GFCI's do go bad sometimes, but they are very cheap to replace.

jnbhobe · May 4, 2010

A dogbone is an adapter you use to go from the 30 amp plug to 15 amp or from 50 amp to 30 amp.

patrick1945 · May 4, 2010

Re: Now I have a much bigger problem with the wiring in my 3055

"Patrick, A GFCI will often trip when a breaker will not. Try to think of them as a super sensitive breaker. Here is a link for more info -> http://en.wikipedia.org/wiki/Residual-current_device I believe Bob Krull asked you if the main 50 breakers were on or off because he was trying to help you isolate your problem. I believe you have a fault in your RV's electric system that will trip a GFCI but not a breaker. You installed what I (& others call a people GFCI) there are also equipment GFCI's which are less sensitive. Now let's see if we can find the problem, do these steps :

1). You stated if you plug in a non-GFCI circuit (inside with an extension cord) you are fine no trip correct and is that still true ?

2). Turn all the RV breakers off including the 50 amp main breaker.

3). Test the new GFCI with a plug in drill or lamp (I've seen brand new GFCI's be defective).

4). Plug a 120 volt radio into the GFCI and turn up the volume so you can hear it from inside at the RV panel. When the silence is deafening you found your problem. In others words when the GFCI trips the radio gets quiet because the GFCI did its job.

5). With ALL AC RV breakers in the off position, plug in your 20 amp to 30 amp adapter only. Do the same one at a time with the 30 to 50 adapter.

6). Now plug in the shore power cord - your RV's main power cord into the last adapter which is still plugged into the GFCI.

7). Now start turning on the breakers, slowly and one breaker at a time, start with the 50 amp main breaker/s, the rest now one at a time - listen for silence.

8). If this doesn't work become the first Amish camper (oops RVer) in your area. No seriously get back so we can help ya when the radio gets quiet... Good Luck. Tom"

Tom & Patti
Lancaster, PA
RV - 3670 RL
TV - 3500 HD DW NBS

Tom,

1. if I plug it into a non-gfci or a non-gfci protected circuit I have power and appliances inside the fw work.
2. I did so
3. I did so
4. I do not have a non-digital radio so used a shop light that I can see from the fw electric panel
5. with the 50 to 15 "dogbone" only plugged into the gfci the gfci is NOT tripped.
6. even with all breakers off the gfci is tripped when I plug it in to the gfci
7. NA

In addition to this I removed the anode (?)..

Thats where I am now.

I am ready for any suggestions

thanks again for your patience and help.
Pat

Willym · May 4, 2010

Patrick,

On your step 6, was the cord plugged in to the trailer or was the GFCI tripping on the attached cord only?

patrick1945 · May 4, 2010

GFCI was not not tripped until the 50 amp electric cord, dogbone and regular extention cord were plugged into the RV. Before that and with the 3 items to the left were connected and plugged into the GFCI, it was not tripped.

Willym said:
Patrick,

On your step 6, was the cord plugged in to the trailer or was the GFCI tripping on the attached cord only?

RollingHome · May 4, 2010

Patrick it appears the problem is in one of your cords. Do these steps in sequence :

a). Plug in adapter ( aka dog bone). Did the GFCI trip ? If NO;
b). Plug the extension cord into the adapter. Did the GFCI trip ? If yes - there's your problem, If NO;
c). Plug the RV 50 amp land line into the extension. Did the GFCI trip ? If yes - there's your problem, If NO;
d). Start flipping the already off breakers to on, when the GFCI trips you found the culprit.

Now about bad cords ; The best trouble shooting aid you have is your eyes, really look intensely at the male and female cord ends, are they dirty, carbonized, charred or in sad shape ? The problem can be something as simple as DIRT between the male prongs, clean it with Lectra Clean, CRC, LPS or alcohol, 800 grit sand paper etc. it has to be clean, almost spotless. These GFCI's are buggers when it comes to sensing the path of current, they trip at the drop of a hat ! Maybe the conductors are shorted inside the connector, this is another trouble area. Some molded cord ends are cheaply made and prone to trouble. The cord is probably still good you may just need one new end, cut the molded end off and replace with a screwed compression type. You are now a circuit detective, Good Luck and keep looking. I believe you are close to solving this problem so don't give up

branson4020 · May 4, 2010

And when it tripped, the twin 50A breakers in the coach were off - correct?

patrick1945 · May 4, 2010

yes they were off

branson4020 said:
And when it tripped, the twin 50A breakers in the coach were off - correct?

My electrical problem involving a GFCI

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