GFCI issues

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GFCI issues

Postby Miriam C. » Sat Sep 23, 2006 8:51 pm

Stans quote on another thread.
the 120V side, I plugged a pigtail that led to a GFI. I then plugged my trailer into that. I made sure all grounds were good. The inverter was grounded to the frame and the trailer skin, as was the GFI. I fried three GFI's before I gave that idea up. I replaced the GFI with a standard grounded outlet. Everything has been fine since.


I asked this question before and got a totally paranoid response. I am going to ask it again but please don't let it be an arguement.

The questions is: Will a GFCI protect from a floating ground if it happens.
Floating ground---if a ground is run to the chassis(metal frame) and there is a fault anywhere in the electrical causing the ground to earth to no longer exist.)

It seems to me that this is exactly what a GFCI is intended to protect against. Maybe I'm looking at it wrong. Any ideas.

Warning
This question is in no way intended as an endorsement of grounding to the frame or not. I haven't been involved in anything electrical personally for a long time and Mike C. hates GFCI's for the above reason (Stans quote) and all the electricians I know won't give an answer because they are unfamiliar with trailer building.

Stan, I would so check to see if I had a leaky something. One GFCI or even two I would blame on faulty sensitive equipment. A third would cause me to think the things were sensitive and picking up something.
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Re: GFCI issues

Postby bdosborn » Sat Sep 23, 2006 9:05 pm

Miriam C. wrote:Stans quote on another thread.
the 120V side, I plugged a pigtail that led to a GFI. I then plugged my trailer into that. I made sure all grounds were good. The inverter was grounded to the frame and the trailer skin, as was the GFI. I fried three GFI's before I gave that idea up. I replaced the GFI with a standard grounded outlet. Everything has been fine since.


I asked this question before and got a totally paranoid response. I am going to ask it again but please don't let it be an arguement.

The questions is: Will a GFCI protect from a floating ground if it happens.
Floating ground---if a ground is run to the chassis(metal frame) and there is a fault anywhere in the electrical causing the ground to earth to no longer exist.)



No. The GFCI doesn't care if a ground is present or not. It works by comparing the current coming in on the hot wire and the current going back on the neutral wire. It will trip if there is a .005A difference or more.

Bruce
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Postby Dee Bee » Sat Sep 23, 2006 9:12 pm

Well Here goes my 2 c.s

I chose not to ground the DC system to the TD frame. Every circuit has its own direct wire return to the battery. I think some call this the "ground" leg in a DC scheme.

I think the term Groundis used differently when talking about AC. AC has two wires, usually commonly called a hot wire and a return wire. Plus wiring codes and standards require an additional ground wire. In schematics I think this is usually shown as green. I did ground my AC wiring to the TD metal frame. I also used a GF outlet. The entire AC sytem shares a common ground connection. When the TD is plugged into AC shore power, the green ground connects to the green ground of the power outlet at the campsite.

I plug an AC to DC converter, which is grounded via a normal three prong plug, into one of my TD AC outlets.

Before and after I connected the AC system I had a friend who is an electrician look over my wiring, outlets, and circuit breaker for an OK.
It has worked fine from the very beginning.

I hope this helps.

I also hope that some electricians join this discussion to help you since I am not trained in the electrical field.
Keep at it, youi'll make it.

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Re: GFCI issues

Postby Miriam C. » Sun Sep 24, 2006 12:33 am

bdosborn wrote:
Miriam C. wrote:Stans quote on another thread.
the 120V side, I plugged a pigtail that led to a GFI. I then plugged my trailer into that. I made sure all grounds were good. The inverter was grounded to the frame and the trailer skin, as was the GFI. I fried three GFI's before I gave that idea up. I replaced the GFI with a standard grounded outlet. Everything has been fine since.


I asked this question before and got a totally paranoid response. I am going to ask it again but please don't let it be an arguement.

The questions is: Will a GFCI protect from a floating ground if it happens.
Floating ground---if a ground is run to the chassis(metal frame) and there is a fault anywhere in the electrical causing the ground to earth to no longer exist.)



No. The GFCI doesn't care if a ground is present or not. It works by comparing the current coming in on the hot wire and the current going back on the neutral wire. It will trip if there is a .005A difference or more.

Bruce


Reading Bruce's cut out I can see I didn't take my question far enough.
Lets say I got to the campground and thier grounding wasn't right. I now don't have a path to earth except my trailer frame.(if I grounded to the frame). I have a floating ground. If I have a short and it touches my frame, the frame is hot. If I touch the frame I am the path to ground.

Will this trip my GFCI and save my buns which were sitting on the tongue? Or does the GFCI require the ground to be in place to work.
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Postby bdosborn » Sun Sep 24, 2006 1:01 am

Miriam,

The short answers is: it depends. If the short is on the downstream protected side of the GFCI outlet it should trip. If it is on the upstream unproteced side it wouldn't. But there's a problem with GFCI outlets, they can go bad over time if there's a lot of transients on the line. So be carefull when you wire the trailer, make sure your wiring is protected from damage and possible contact with the frame.
Bruce
Last edited by bdosborn on Sun Sep 24, 2006 1:49 am, edited 2 times in total.
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Postby Miriam C. » Sun Sep 24, 2006 1:25 am

:applause: :thumbsup:
Got it! Make sure the extention cord and inlet are in real good shape everytime. Everything else will be in a box or conduit. I won't have 120ac going to the front of the ttt. All in the galley. ;)
Thank you Bruce.

Dee Bee I appreciate your detailed answer. It is very helpful.

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