GFI electrical outlet problem

[mike2011]

I have a 1999 southwind that has an unusual electrical problem. While driving down the road I had a tire blow out on the drive axel. When I went back to look at it I noticed a number 6 ground wire had been knocked loose --- actually pulled down out of the floor by the disintegrating tire. I wrapped off the end and tie wrapped it up. I didn't reconnect it to anything. I tried to find where it had been connected with no luck. The other end is connected to the chassis frame. A few weeks later I noticed the GFI outlet above the kitchen sink wasn't working (the disturbed ground wire and the outlet are about 6 feet apart) . I replaced the outlet --- still didn't work. I checked the voltage and it only showed 35 volts --- when I take the outlet off the wires and check the wire voltage  --- black and white shows 112 while black and ground show 118 VAC. I'm not sure if they are connected but this one has me whipped --- any thoughts? Any ideas where the large ground wire connects?

 

[Gary RV_Wizard]

First, the outlet problem. Where did you measure 35 volts?  Across the two flat slots? That should be the same 112 you measured between black & white wires.  Black to ground may be a slightly different than black/white, though I would not anticipate a 6v difference. Maybe a poor connection on the white wire somewhere. In any case, this problem would not seem to be related to the mystery wire.

A 6 gauge wire is a hefty one, so probably a ground strap for either generator, inverter (if you have one), house batteries, or 12v converter.

 

[mike2011]

Thanks Gary --- the 35 volts came after I hooked up the outlet to the black and white wires measured across the the 2 flat slots. I then took the GFI outlet off and put a regular outlet on the end of the black and white wires -- it then measured 112 at the wires and the slots until I plugged in a light to test it. The light would not come on and the voltage across the wires and flat slots dropped to 33-35 VAC. I went back and checked the voltage at the breaker for that circuit with no light plugged in and got 112. Next I will check the voltage at the breaker with the light plugged in. This is the only outlet in the coach that has a problem.

As for the heavy gauge wire -- when it was pulled through the floor, the free end was tied into a knot and the wire was actually recessed back into the insulation by about an inch -- it looked as though it had never been connected to anything.  I did find a white wire at the terminal block inside the circuit breaker box that looked burnt on the end -- I cleaned it up and reconnected it and got no change. The white wire went from the terminal block to a large contact relay also in the breaker box.  For now I'm stumped..

 

[SeilerBird]

The ground wire and the GFI problem are two completely different and unrelated problems. GFIs don't use the ground for anything other than to satisfy the electrical code.

 

[Gary RV_Wizard]

The voltage change from 35 to 112 was undoubtedly because the connection improved when you swapped outlets. GFCI or not has nothing to do with it.

Except for the house battery (12v) ground, ground straps to the chassis are for safety reasons and not functional.

 

[Ernie n Tara]

I'd check the other end of the wires on the GFI. It sounds as if there is a bad connection, probably on the hot wire.

JM2C,

Ernie

 

[mike2011]

Thanks for the input guys---I'll keep you posted as I try new things.

 

[ChasA]

The voltage dropping when you plug a load in is an indication of a loose or corroded connection. Unplug from your AC power supply and disconnect all yor batteries. Then open your AC power center in your motor home and inspect and tighten all screws on the back of the circuit breakers and the bus bars where the white wire connect. Look for signs of overheated wires.

 

[mike2011]

FIXED IT!  First I attached a GFI outlet to a 6' length of 12/2. Then I figured out which breaker controlled my "bad circuit". I then disconnected the "bad" wiring from the breaker and common and ground connections in the breaker box. I then substituted the "new" 6' lead I had built into those connections in the breaker box --- it worked perfect. So, this verified that the breaker, connections and power going into the box were good  and that the problem was in the wiring between the breaker box and the original outlet. I then traced the wiring and found it went through 2 J-boxes. I opened the first J box and everything looked fine. I then opened the second J box (of course the harder one to get to) and found the black wire for that circuit had gotten so hot it had actually partially melted the wire nut. I took the wires apart, cleaned them really good, wired them back together with a new wire nut and tape and everything works perfectly. Thanks for all the helpful advice guys! Great site with great people. 

 

[ChasA]

Mike,
Glad you got it fixed. I recommend that you replace the wire nuts with crimp connectors. You can get crimp connectors that look like wire nuts, but you crimp them onto the wire ends rather than screwing them on.

 

[SeilerBird]

Mike,
Glad you got it fixed. I recommend that you replace the wire nuts with crimp connectors. You can get crimp connectors that look like wire nuts, but you crimp them onto the wire ends rather than screwing them on.

Excellent idea. I have always said wire nuts do not belong in a vehicle. Too much vibration.

 

[mike2011]

good idea on the crimps  --- I always wrap wire nuts with electrical tape starting on the wire nut and wrapping down onto the wires. Hopefully this will stand up to the vibrations.

 

[Gary RV_Wizard]

I don't think you will have a problem with a well-applied and taped wire nut, but I would still use crimps or butt connectors on any connection that is of a permanent nature. It's the most reliable and vibration is an issue in any RV. Even the screw terminals on the load center, transfer switch, etc. will work loose over time.

 

[SeilerBird]

I don't think you will have a problem with a well-applied and taped wire nut...

Applying the wire nut is not the problem. The problem is preparing the wires before the wire nut is installed. Most people don't prepare the wires properly and that causes the problems. Before a wire nut is installed the wires must be twisted together and mechanically sound. Too many people insert the wires into the wire nut, twist a few times and call it good. That is a recipe for disaster. With the vibration that RVs create driving down the road one or more of the wires can fall out or become loose and create heat, which is what happened to the OP.

 

[Gary RV_Wizard]

Too many people insert the wires into the wire nut, twist a few times and call it good.

Yeah, and unfortunately that is exactly what the printed instructions on a retail package of wire nuts says to do. They are so busy trying to convince you it is fast & easy that they ignore reliability. Ditto with the press-in connectors on the back of switches and outlets.

 

[mike2011]

thanks guys --- all good stuff