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Old 11-20-2010, 09:50 AM   #1
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Electrical - GFI Problems

I cannot plug my M/H into any GFI circuit without blowing the cb! I have managed to isolate 3 circuits that are causing the problem. If I turn off the 3 AC cb's on the panel, then I can plug into a GFI circuit. The 3 circuits are: fridge, a/c & washer/dryer. I have tested the three circuits but no problem found.

Any ideas?

Thanks, Derek

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Old 11-20-2010, 10:12 AM   #2
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GFI or GFCI breakers are looking at the current on the ungrounded (hot) wire and comparing the current to the grounded wire (neutral). if the comparison is not within tolerance of the GFCI breaker, it will trip.

because of the way GFCI breakers work, the neutral conductor cannot be connected to the equipment ground conductor, or the breaker will see less current on the grounded neutral. the neutral wire could be shorted to ground elsewhere and the same problem would result.

another reason for the GFCI breaker tripping could be moisture in the electrical compartments of the appliances. moisture could introduce a minor short into the circuit and this would cause an imbalance of current on the grounded versus the ungrounded conductors. the short may not be enough to feel to the touch as it may be measured in milliamps. GFCI circuit breakers are manufactured to be very sensitive.

you say you've tested the three circuits; have you tested the appliances also? the GFCI circuit breaker is tripping for a reason. if you can't find the problem yourself, i'd have a qualified electrician have a look.

hope this helps.

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Old 11-20-2010, 10:52 AM   #3
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You may want to try unpluging all 3 of the appliances......( or disconnecting the load side of the breaker ). Then add each appliance back into the system......and see exactly which appliance is causing the breaker to trip. This will narrow it down to the one troubled appliance.

After you determined which appliance is the problem.......maybe try running a extension cord direct from the GFCI to that appliance.....this will prove .....the appliance is defective or the problem is in the coach wireing.

Hope it helps.
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Old 11-21-2010, 01:59 AM   #4
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If the coach will operate all circuits on a 30 or 50 amp service but trips a 15 or 20 amp GFCI the problem is 90% of the time a bad heating element. There is enough current leakage from the element's filament to frame ground for the GFCI to trip but not enough to trip a standard circuit breaker. Unplug the refrigerator from the receptacle and retry. If the GFCI hold the bad element is in the refrigerator. If not keep checking individual appliances as stated above to find the culprit. Replace the defective element and you should be good to go.
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Old 11-21-2010, 06:34 AM   #5
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In residential wiring, the ground and the neutral are bonded in the electrical box. In an RV, the ground (frame of the RV) and the neutral are supposed to be separate. If someone has done any rewiring in the RV and they have connected the ground and neutral together, that will probably trip a GFCI, especially if the polarity (hot and neutral) are reversed.
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Old 11-21-2010, 06:55 AM   #6
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DOn't rule out the GFI either, it could be bad. I have had them overloaded before (due to excessive moisture) and became faulty. Had to change and all was good.
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Old 11-21-2010, 02:06 PM   #7
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Thanks for all the suggestions. I have tested all circuits as mentioned above with help from a technician. That is how I found out which ones were causing the problem. If I turn off the c/b's to the frig, a/c & washer/dryer, then everything else will work fine on the GFI. If any one of these 3 circuits are active, then the GFI blows. It is not a problem when plugged into a regular 15 amp circuit, 30 or 50 amp shore power.
As suggested, I will try to trace the ground and neutral wires of each circuit, to make sure they are separate. I will also try each appliance separately, using an extension cord, to determine if it is the actual appliance or circuit causing a short.

Thanks for all the tips. Derek (now in Charleston, SC)
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Old 11-21-2010, 09:04 PM   #8
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I had a similar issue. Whenever I turned on the rooftop A/C the GFCI would trip. To make along story short, the cause was the heating element in the refrigerator. Once it was isolated, and subsequently replaced, no more GFCI trips.
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Old 11-21-2010, 09:10 PM   #9
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I had the same problem on an Itasca Suncruiser. I thought it was a moisture problem, because the appliances worked fine when plugged into non-GFI circuits, but would always trip the GFI if it was present.

I found that it was loose neutral where power enters the rig at the switch box. Tightened it, and no more problems. Then, I took the cover of the c/b panel, and tightened all the lugs on the buss bar and the breakers. Found alot of loose connections here too. The danger with the loose connections is that they build up very high resistance, and can ultimately cause a fire. I found several that showed signs of over-heating.

Good luck.

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Old 11-22-2010, 10:29 AM   #10
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I had the ground and neutral mix up in the box where the gen wires meat house wires 4by4 in. 30 amp. I add a 12 amp wire for rear air, works good.
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Old 11-23-2010, 02:42 PM   #11
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Mine was tripping the GFI. I isolated it to the microwave. With an extension cord, the microwave was fine. It turned out that the outlet the microwave plugged into was full of dead ants. So small I had to use powerful magnifying lenses to see them. We were in really humid weather and they absorbed enough moisture to conduct electricity. Cleaned them out and all has been fine since. Good Luck, HarveyP
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Old 11-24-2010, 09:56 AM   #12
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Aye, Laddie

If you be Irish it might be Leprechauns dat be haunting you.

If you are running power from a secondary power panel, you may not be wired correctly.

Older homes and outbuildings have three wire circuits where the ground and neutral are combined in one wire. Pre GFI days.

Also, all secondary panels should not be grounded, except back at the main panel.

What I am trying to say, is that you need a separate neutral wire running from the main power box.

Neutral returns unused juice to main box and back out to utility system. If using three wire configuration, the GFI picks up on the unused juice and snaps off................

Now..............the ground and neutral are bonded together in the main power box. It doesn't seem logical, but, apparently it works.

I discovered my outside panel was a three wire set up.

Had to pay out serious "geeters" to add separate # 6 neutral wire.

Three wire will work for 220v only.

If you try to use one leg to tap 110 v you are looking for trouble.

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