Grounding

[cbwood]

>Not remembering this wire and having just moved my box to the sidewall of the
>compartment about 6 months ago, I went out and looked at my box. I do not
>have this ground wire. I don't know why I don't have this because the wiring
>diagrams for 1975-76 and 1977-78 Motorhomes built by GMC show this 8 gauge
>braided wire going from the ground buss in the breaker box to chassis ground.
> Since I have had the GMC for almost 19 years I know it was not changed by a
>prior owner. The diagram doesn't show where it is grounded. I would assume
>that it must be to the chassis somewhere close to the box. If one end is
>detached from the ground buss in the circuit breaker box, it can be checked
>for a good ground by using a VOM (volt ohm meter). This information applies
>to the GMC built models but is not necessarily correct for the companies that
>built on GMC Transmode chassis, such as Coachman built Royales.
>
>Interestingly, when going through the diagrams, I also see that sometime in
>1977 GM added a GFI circuit (ground fault interrupter) that protects the
>Bath, Galley, Outside Plug, Refrigerator and Bedroom. My 1977 was
>manufactured in early 1977 and does not have a GFI.

Looks like I need to ground my chassis to the aluminum in the left rear area.
I probably would want to install the GFI also.Where physically did they put this?

- -------------------------------------------------------------
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[chuck blanford]

>
>>Interestingly, when going through the diagrams, I also see that sometime
in
>>1977 GM added a GFI circuit (ground fault interrupter) that protects the
>>Bath, Galley, Outside Plug, Refrigerator and Bedroom. My 1977 was
>>manufactured in early 1977 and does not have a GFI.

>
>Looks like I need to ground my chassis to the aluminum in the left rear
area.
>I probably would want to install the GFI also.Where physically did they put
this?
>

My 77 Kingsley has the GFI located in the Outside Plug receptacle.

Chuck
North Idaho

 

[chuck blanford]

Hi Glenn

I know what you mean about that priority list. I've purchased several items
that I've yet to install - Statpower 40+, spoiler (Front air dam), Onan air
deflector, wheel bearings, control arm bushings, Alcoa wheel centers, Dana
rebuild kit, SS brake lines, front brake hoses, Thomas 317 compressor, etc.

I met Dave Mumert from Calgary last Friday. He's a "wanna-be", and
delivered 2 wrecking yard suspension air compressors for $20. Nice fellow.
They come to Post Falls to shop at the Factory Outlets.

I envy the retired fellows that have more time to spend with their coaches!

Chuck

- -----Original Message-----
From: Gplymate
To: gmcmotorhome
Date: Wednesday, September 29, 1999 7:47 PM
Subject: Re: GMC: Grounding

>
>Hi Chuck,
>
>The outside plug was an option, and I believe the GFI was part of it. My
78
>(cheap model) does not have the outside plug, and I have no GFI.
>
>But, I can always add one. That's about no. 54 on my priority list.
>
>Glenn
>78 Kingsley
>Independence, OR
>

 

[john szalay]

A
> REMEMBER Aluminum and copper should NEVER be connected to-gether in an
>electric circut WITHOUT a proper common bonding interface/connector
>certified for use with Aluminum wiring/bus bars ...... Aluminun and Copper
>in wiring can be a major problem......... corrosion, wire overheating and
>possible fires can result.
>
> John Szalay
> 73 GMC PD
> Louisville Ky
> >>
>
>John - I am confused by this message. I wrote the first three lines saying I
>did not have the ground wire. Someone else wrote the next three lines saving
>they had to ground their chassis and install a GFI. Somehow these statements
>by two different people got mixed into one statement when you sent your
>message.
>
>You are correct that the house wiring requirement for aluminum/copper
>connections is a special situation. This applies to the use of aluminum
>wire. However, the RV code is different from the house building code. There
>is no aluminum wire in the GMC. Check all of the many ground points in your
>GMC. Most of them are copper wire to a steel screw attached to an aluminum
>frame or in the front to an aluminum plate? Since our frames are aluminum
>there is no choice. This is part of the reason that poor ground connections
>affect the cruise control, lights, gauges, etc. Many of us have posted over
>the last year that these connections should be cleaned and a dielectric
>compound be used to protect the connection from corrosion. Whenever
>something electrical starts misbehaving the first thing I do is check its
>ground.
>
>Emery Stora
>77 Kingsley
>Santa Fe, NM
>


Correct, and IF you use the Di-electric grease it will take care of
the problem, but not everyone knows that. Thats the reason for my warning
any dis-similiar metal connections to aluminum either wire or solid has the
potential for resistance and resulting heating. Aluminum will oxidize very
fast after cleaning, best cleaning is with a clean stainless brush. and
processed or coated very soon after the cleaning to prevent the oxide from
forming. ( or welding) the aluminum oxide formed is the culprit and anything
such as the dielectric grease or silicon grease helps to prevent the oxide
from forming... you made a very valid point......

John Szalay
73 PD
Louisville Ky