| GFCI fault [message #216185] |
Mon, 29 July 2013 20:59  |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
Karma: 0
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I recently returned from a problem free trip. I let the coach sit for a couple days before I realized that I still had some beer in the fridge. I went to plug it in so that I could cool it down and right when I plugged the cord into my outside outlet I heard the GFCI pop. At that exact same time I saw a very plump mouse fall down from the underside of the coach about mid length and flop on the ground and then run away! SOB!! I figured the little prick was chewing on a power line and was zapped when I plugged it in.
With that in mind I started to try and find the ground fault. I looked under the coach at the same location and couldn't find anything that he could be chewing on. I went inside, killed all the breakers and tried them one by one to find the short. I would trip the GFCI no matter which one was powered once I put load on the circut. Later that night it dawned on me that the short was a neutral to ground rather than power to ground short.
Tonight I was able to isolate the short to the line powering the fridge on the other side of the coach. After hours of trying to find the line the mouse was chewing on it probably was an innocent bystander that was zapped when I plugged it in before the GFCI blew.
Everything runs fine now but I had to disconnect the ground lead from that circuit to get it to work. I play to trace the line back to the power box to either find the fault or open a path to pull a new line.
All of the AC power in my rig was replaced by the previous owner so the quality is suspect.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: GFCI fault [message #216188 is a reply to message #216185] |
Mon, 29 July 2013 21:04  |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
Karma: 0
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Senior Member |
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Come the think of it, I saw a similar thing while watching a ESD test on a machine while it was undergoing EMC testing. The tech hit it with a 30K V charge and all kinds of bugs that were crawling on it dropped off and fell on the ground.
Maybe that could be a new form of pest repellant?
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: [GMCnet] GFCI fault [message #216190 is a reply to message #216185] |
Mon, 29 July 2013 21:08 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Jerrod,
You need to make sure that the ground and neutral are separated in the breaker box. This means that the ground wire should not be connected to the neutral bar in the box. This can also cause the GFI to trip. The bare copper ground wires should be connected to the green ground on the incoming power cable. If I am wrong, Ken B correct me.
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
On Jul 29, 2013, at 9:59 PM, jerrod winter <jerrod_beth@msn.com> wrote:
>
>
> I recently returned from a problem free trip. I let the coach sit for a couple days before I realized that I still had some beer in the fridge. I went to plug it in so that I could cool it down and right when I plugged the cord into my outside outlet I heard the GFCI pop. At that exact same time I saw a very plump mouse fall down from the underside of the coach about mid length and flop on the ground and then run away! SOB!! I figured the little prick was chewing on a power line and was zapped when I plugged it in.
>
> With that in mind I started to try and find the ground fault. I looked under the coach at the same location and couldn't find anything that he could be chewing on. I went inside, killed all the breakers and tried them one by one to find the short. I would trip the GFCI no matter which one was powered once I put load on the circut. Later that night it dawned on me that the short was a neutral to ground rather than power to ground short.
>
> Tonight I was able to isolate the short to the line powering the fridge on the other side of the coach. After hours of trying to find the line the mouse was chewing on it probably was an innocent bystander that was zapped when I plugged it in before the GFCI blew.
>
> Everything runs fine now but I had to disconnect the ground lead from that circuit to get it to work. I play to trace the line back to the power box to either find the fault or open a path to pull a new line.
>
> All of the AC power in my rig was replaced by the previous owner so the quality is suspect.
> --
> Jerrod Winter
> 1977 Palm Beach
> Green Jelly Bean
> Twin Cities, Minnesota
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: GFCI fault [message #216193 is a reply to message #216185] |
Mon, 29 July 2013 21:34 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Right --should be bonded at feed source panel only. For example at the main panel in your home and that would then feed the GMC. GFCIs work by differential current flow on hot and neutral. Hot and neutral need to have equal opposite flow. If G and N are bonded the there are multiple return paths and the neutral won't carry as much as it should and trip the GFCI
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: GFCI fault [message #216196 is a reply to message #216185] |
Mon, 29 July 2013 21:52 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
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The neutral and ground bars are seperate in the box. I have an outlet tester that confirms the rest of the outlets are hooked up correctly and also tests the GFCI operation. My problem appears to be a partial neutral to ground short somewhere in the line feeding the fridge. I'll try a continuity test tomorrow to confrim (with the power off of course).
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: GFCI fault [message #216200 is a reply to message #216185] |
Mon, 29 July 2013 22:07 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
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Should the coach body be tied to the ground terminal?
I haven't checked mine yet but that would seem to make sense.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: GFCI fault [message #216206 is a reply to message #216185] |
Mon, 29 July 2013 22:42 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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This is a vary common failure of the heating element. The failure occurs with the heat both off and on.
DISCONNECT the neutral wire going to the heating element and try again to see if the GFI trips. You can get to that wire easily in the fuse box rather than go to the heater itself.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: GFCI fault [message #217628 is a reply to message #216185] |
Sat, 10 August 2013 08:46 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
Karma: 0
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I ended up fixing several issues
There was a PO installed outlet that the ground wire was in close proximity to the neutral. Over time, the ground found its way over to the neutral.
The water heater has a ground to neutral short.
The main ground coming in from the power cord was not capped off and not attched to the ground lug in the power box. That caused the second neutral short to show up.
There was some wiring that was just twisted and taped together hanging behind the cabinet. I replaced that with one long run and proper connections.
I double checked all the circuits with a GFCI tester and it now looks like everything works. Except the water heater, thats unplugged for now.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: [GMCnet] GFCI fault [message #217643 is a reply to message #217632] |
Sat, 10 August 2013 10:23 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Jerrod,
The heater element is shorted and needs to be replaced. This is a common failure.
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
On Aug 10, 2013, at 10:21 AM, Dan Gregg <gregg_dan@hotmail.com> wrote:
>
>
> Jerrod, don't you feel good when you accomplish something like this while sitting on your own property? I found an air leak yesterday to my q bags that I have been chasing for years.
> A good wife will pick up on your sense of accomplishment.
> Thanks for the report.
> Dan
>
> --
> Dan & Teri Gregg
> Dexter, Mo.
>
> http://danandteri.blogspot.com/
>
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>
>
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GMCnet mailing list
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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