Home » Public Forums » GMCnet » [GMCnet] Electrical question
| [GMCnet] Electrical question [message #24195] |
Fri, 10 October 2008 22:46  |
Kim David McNeill Sim
Messages: 26
Registered: May 2008
Karma: 0
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Junior Member |
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Today I was finally able to get the time to replace the power
converter -not the original buzz box, with the PD9270 70 amp
Converter charger. When I disconnected the old box I found that the
"ground" wire was only connected to the negative side of the output.
It did not sit right with me so after reading more instructions- yes
I really do read instructions, I put in a new ground wire. My problem
is according to the instructions that came with the PD9270, it should
be grounded to the RV frame. Since this is my first time digging
around electrically in my coach, I converted the ground wire (12
gauge) I stripped out of some old romex I had and grounded the PD9270
to the electrical box grounding bar, which as far as I can see is
grounded quite well to a lot of other "things". The question is, is
it safe or do I have to find a true connection to the frame?
Yes I am sure I should start digging around to find out what wires go
where and what is grounded where and to what, but everything works
and I really am a little leery of messing with things that work-well
so far.
Hope some of you electrical geniuses might shed some light on this
for me.
Thanks
Kim
Kim and Pat Simmons
'76 Eleganza II
New Richmond, Ohio
TZE166V101526
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| Re: [GMCnet] Electrical question [message #24198 is a reply to message #24195] |
Fri, 10 October 2008 23:25  |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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Kim,
The ground needs to be connected to the body frame which ultimately
ends up grounded to the house and engine batteries.
I'm doing some rewiring, I've mounted a ground buss bar behind the oven to connect the wires, and one heavy #4 from the ground bar to the house batt, also a #10 to the frame.
Poor connections in the power and/or the ground causes wires to heat up and over time lead to a possible fire.
I have not been surprised at the corrosion that I've found at the connections. Good luck.
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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| Re: [GMCnet] Electrical question [message #24299 is a reply to message #24198] |
Sun, 12 October 2008 11:57 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Ground systems are confusing in the GMC to say the least. There are at least 3 different ground systems and some cross connections between three.
1 120v AC ground for the shore / Onan power
2. 12 volt DC ground for the house systems
3. 12 volt ground for the engine systems
You question really is which system do I ground the chassis of the converter to?
The answer is #2 above - the 12 DC ground for the house. This is the aluminum body of the coach.
This is NOT the steel frame of the coach, the engine, the Onan, or the shore power.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Electrical question [message #24328 is a reply to message #24195] |
Sun, 12 October 2008 17:40 |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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Don't the house and the motor 12 volt systems share the same ground? I always assumed that the couch aluminum frame was electrically connected to the frame and they both served as a ground. I realize that there are rubber isolators between the body and the frame, but there must still be a common ground (shouldn't there?).
Also, does it bother anyone else that the ground wires can be different colors depending on the unit connected? It appears that different electrical accessories have black, red, white, or other wires that all could end up being the ground. You have to watch the wiring diagram and pray some prrevious owner didn't foul things up!
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: [GMCnet] Electrical question [message #24329 is a reply to message #24327] |
Sun, 12 October 2008 17:49 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Kim,
The house panel ground bar SHOULD be at the same potential as the body
ground. But I wouldn't depend upon it. I'd remove the rear panel from
the converter compartment to access the ground lug there. I'd remove
all the attached wires, clean them and coat them with an anti-oxidant
paste like OxyGard. Then reattach them, including the ring lug on the
end of a 12 gauge stranded ground wire from the converter, with star
washers to ensure a good, almost-permanent connection.
In all of this, I'm assuming that you are indeed talking about the
GROUND buss bar (probably green wires) and not the NEUTRAL buss bar
(white wires). The NEUTRAL must NEVER be connected to the GROUND inside
the motorhome -- that connection must only be made at the shore power
box. (Plugging in the Onan WILL connect them, but that doesn't count.)
Ken Henderson
Americus, GA
www.gmcwipersetc.com
'76 X-Birchaven
'76 X-Palm Beach
Kim David McNeill Simmons wrote:
> Ok, so if I connected the new ground wire to the ground buss bar of
> the electrical house panel box "should" that not be the same?
> ...
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| Re: [GMCnet] Electrical question [message #24349 is a reply to message #24329] |
Sun, 12 October 2008 19:40 |
Kim David McNeill Sim
Messages: 26
Registered: May 2008
Karma: 0
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Junior Member |
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Ken,
I think I saw that way in the back- the panel you said to take off is
no longer there. But since my wife was busy and my arms are not long
enough and I am most definitely not skinny enough, that just was not
going to happen. But the answer to your question as to the bar I
connect my ground to, no color just bare copper wires were going to
the panel as I remember it.
SO if I am suppose to connect my new ground to that one rather small
in the distance ground lug, just how does one take out that bolt, do
everything you suggested without dis-mantling the entire drawer
system above the electrical area? Is there a secret panel or access
code or does everyone know very small people who climb into these
very tight spaces? If I reach in there nothing but my arm is going in
which means what ever I loosen up will likely never be tightened up
or cleaned up correctly, let alone my putting a new wire in there.
Any suggestions, I am not going anywhere so whatever I need to do I
guess i will do
Thank you
Kim
On Oct 12, 2008, at 6:49 PM, Ken Henderson wrote:
> Kim,
>
> The house panel ground bar SHOULD be at the same potential as the body
> ground. But I wouldn't depend upon it. I'd remove the rear panel
> from
> the converter compartment to access the ground lug there. I'd remove
> all the attached wires, clean them and coat them with an anti-oxidant
> paste like OxyGard. Then reattach them, including the ring lug on the
> end of a 12 gauge stranded ground wire from the converter, with star
> washers to ensure a good, almost-permanent connection.
>
> In all of this, I'm assuming that you are indeed talking about the
> GROUND buss bar (probably green wires) and not the NEUTRAL buss bar
> (white wires). The NEUTRAL must NEVER be connected to the GROUND
> inside
> the motorhome -- that connection must only be made at the shore power
> box. (Plugging in the Onan WILL connect them, but that doesn't count.)
>
> Ken Henderson
> Americus, GA
> www.gmcwipersetc.com
> '76 X-Birchaven
> '76 X-Palm Beach
>
>
> Kim David McNeill Simmons wrote:
>> Ok, so if I connected the new ground wire to the ground buss bar of
>> the electrical house panel box "should" that not be the same?
>> ...
> _______________________________________________
> GMCnet mailing list
> Gmclist@temp.gmcnet.org
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Electrical question [message #24359 is a reply to message #24349] |
Sun, 12 October 2008 20:52 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Senior Member |
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Kim,
If you can't reach the main grounding lug, you'll just have to do the
best you can -- as you suggest, it's better to leave it alone than to
screw it up. My suggestion stands if you can get help that can reach
it, but I know of no easy way to gain better access. If you ever see
symptoms of a grounding problem, you could run a wire through an
existing, or new, hole in the floor to the outside, where you could
fasten the wire to the lower main longitudinal extrusion. That's
probably not justified at this point.
What I'm wondering right now is where the negative lead from your
converter is connected? That's the one that really needs to connect
cleanly to the body ground to preclude problems with living area 12 VDC
devices. You definitely DO NOT want to hook that one to the 120 vac
ground buss.
If all the wires going to the buss bar are bare, it certainly should be
the ground bar.
Ken Henderson
Americus, GA
www.gmcwipersetc.com
'76 X-Birchaven
'76 X-Palm Beach
Kim David McNeill Simmons wrote:
> Ken,
> I think I saw that way in the back- the panel you said to take off is
> no longer there. But since my wife was busy and my arms are not long
> enough and I am most definitely not skinny enough, that just was not
> going to happen. But the answer to your question as to the bar I
> connect my ground to, no color just bare copper wires were going to
> the panel as I remember it.
> SO if I am suppose to connect my new ground to that one rather small
> in the distance ground lug, just how does one take out that bolt, do
> everything you suggested without dis-mantling the entire drawer
> system above the electrical area? Is there a secret panel or access
> code or does everyone know very small people who climb into these
> very tight spaces? If I reach in there nothing but my arm is going in
> which means what ever I loosen up will likely never be tightened up
> or cleaned up correctly, let alone my putting a new wire in there.
>
> Any suggestions, I am not going anywhere so whatever I need to do I
> guess i will do
>
> Thank you
>
> Kim
> On Oct 12, 2008, at 6:49 PM, Ken Henderson wrote:
>
>> Kim,
>>
>> The house panel ground bar SHOULD be at the same potential as the body
>> ground. But I wouldn't depend upon it. I'd remove the rear panel
>> from
>> the converter compartment to access the ground lug there. I'd remove
>> all the attached wires, clean them and coat them with an anti-oxidant
>> paste like OxyGard. Then reattach them, including the ring lug on the
>> end of a 12 gauge stranded ground wire from the converter, with star
>> washers to ensure a good, almost-permanent connection.
>>
>> In all of this, I'm assuming that you are indeed talking about the
>> GROUND buss bar (probably green wires) and not the NEUTRAL buss bar
>> (white wires). The NEUTRAL must NEVER be connected to the GROUND
>> inside
>> the motorhome -- that connection must only be made at the shore power
>> box. (Plugging in the Onan WILL connect them, but that doesn't count.)
>>
>> Ken Henderson
>> Americus, GA
>> www.gmcwipersetc.com
>> '76 X-Birchaven
>> '76 X-Palm Beach
>>
>>
>> Kim David McNeill Simmons wrote:
>>> Ok, so if I connected the new ground wire to the ground buss bar of
>>> the electrical house panel box "should" that not be the same?
>>> ...
>> _______________________________________________
>> GMCnet mailing list
>> Gmclist@temp.gmcnet.org
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>
> _______________________________________________
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> Gmclist@temp.gmcnet.org
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Electrical question [message #24367 is a reply to message #24327] |
Sun, 12 October 2008 21:20 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Yes, But......
We are not dealing with the 120 VAC safety ground in this case. The 120 volt safety ground is handled by the power cord connection to the converter. The -12 volt current carrying ground is also handled by a different lead. Just hook the lead in question to the motorhome aluminum body and be done with it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Electrical question [message #24386 is a reply to message #24349] |
Sun, 12 October 2008 23:50 |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
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Senior Member |
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Kim David McNeill Simmons writes...
> Ken, I think I saw that way in the back- the panel you said to take
> off is no longer there. But since my wife was busy and my arms are
> not long enough and I am most definitely not skinny enough, that
> just was not going to happen. But the answer to your question as to
> the bar I connect my ground to, no color just bare copper wires
> were going to the panel as I remember it.
Any way you could post a picture of your power panel including this
ground bus?
The ground wires to the 12-volt house ground should not be bare
copper. On my coach, they have black insulation.
Both Kens are right: The 12-volt house ground should be wired to the
aluminum body. The 12-volt chassis ground should be wired to the
engine block and the frame. At several places in the coach, the two
are connected together, but even if they weren't, everything should
work.
No part of the 12-volt systems should enter the 120VAC panel or any
associated junction box. The safety ground on 120VAC is a ground bus
with bare wires, but that is the safety ground for AC, not the 12-volt
grounding bus, which should be outside the power panel.
Rick "a little worried about the descriptions here and wanting a
picture" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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'73 Glacier 230 "Jaws"
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| Re: [GMCnet] Electrical question [message #24408 is a reply to message #24329] |
Mon, 13 October 2008 08:52 |
shawnee
Messages: 422
Registered: February 2004
Location: NC
Karma: 0
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[quote title=GMCWiperMan wrote on Sun, 12 October 2008 18:49]Kim,
The house panel ground bar SHOULD be at the same potential as the body
ground. But I wouldn't depend upon it. I'd remove the rear panel from
the converter compartment to access the ground lug there. I'd remove
all the attached wires, clean them and coat them with an anti-oxidant
paste like OxyGard. Then reattach them, including the ring lug on the
end of a 12 gauge stranded ground wire from the converter, with star
washers to ensure a good, almost-permanent connection.
In all of this, I'm assuming that you are indeed talking about the
GROUND buss bar (probably green wires) and not the NEUTRAL buss bar
(white wires). The NEUTRAL must NEVER be connected to the GROUND inside
the motorhome -- that connection must only be made at the shore power
box. (Plugging in the Onan WILL connect them, but that doesn't count.)
Ken Henderson
Americus, GA
www.gmcwipersetc.com
'76 X-Birchaven
'76 X-Palm Beach
Kim David McNeill Simmons wrote:
> Ok, so if I connected the new ground wire to the ground buss bar of
> the electrical house panel box "should" that not be the same?
> ...
_quote]
Although the house, auto and Onan ground would seem to be the same, they can be different slightly or greatly. If the grounds have not been cleaned in a long time the corrosion will cause resistance and give a voltage drop across them. The more corrosion, the more difference. If you haven't cleaned them recently, it would be a good idea to do it.
Gene Dotson
74 Canyonlands
www.bdub.net/Motorhome_Enhancements New Windows and Aluminum Radiators
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| Re: [GMCnet] Electrical question [message #24493 is a reply to message #24386] |
Mon, 13 October 2008 19:17 |
Kim David McNeill Sim
Messages: 26
Registered: May 2008
Karma: 0
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Junior Member |
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Rick,
I will put that on my to do list this week. Teaching all day today
and Wednesday and Tuesday and Thursday are starting to book up fast,
Friday is a maybe as Saturday I am traveling to Lexington to talk
about Star Wars packaging photography I use to do. Then again maybe
on Sunday might be a good time to grab that photo and post it.
Now you are starting to get an idea as to why this list is so
important to me, it provides short cuts to some serious information.
As I said it looks like I need to take all the information I have
received and put in a new wire but along the way maybe I should also
put in a new ground buss that would be easily accessible to big
people like me.
Thanks to all
Kim
Kim and Pat Simmons
'76 Eleganza II
New Richmond, Ohio
TZE166V101526
On Oct 13, 2008, at 12:51 AM, Rick Denney wrote:
> Kim David McNeill Simmons writes...
>
>> Ken, I think I saw that way in the back- the panel you said to take
>> off is no longer there. But since my wife was busy and my arms are
>> not long enough and I am most definitely not skinny enough, that
>> just was not going to happen. But the answer to your question as to
>> the bar I connect my ground to, no color just bare copper wires
>> were going to the panel as I remember it.
>
> Any way you could post a picture of your power panel including this
> ground bus?
>
> The ground wires to the 12-volt house ground should not be bare
> copper. On my coach, they have black insulation.
>
> Both Kens are right: The 12-volt house ground should be wired to the
> aluminum body. The 12-volt chassis ground should be wired to the
> engine block and the frame. At several places in the coach, the two
> are connected together, but even if they weren't, everything should
> work.
>
> No part of the 12-volt systems should enter the 120VAC panel or any
> associated junction box. The safety ground on 120VAC is a ground bus
> with bare wires, but that is the safety ground for AC, not the 12-volt
> grounding bus, which should be outside the power panel.
>
> Rick "a little worried about the descriptions here and wanting a
> picture" Denney
>
> '73 230 Ex-Glacier "Jaws"
> Northern Virginia
>
> _______________________________________________
> GMCnet mailing list
> Gmclist@temp.gmcnet.org
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Electrical question [message #68476 is a reply to message #24195] |
Sun, 27 December 2009 12:20 |
rallymaster
Messages: 662
Registered: February 2004
Location: North Plains, ORYGUN
Karma: -4
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Senior Member |
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Yup, sure did. Kills everything.
Parts house question,"78 Toronado, what's that?" Then, "Four foot
lengths of fusible link wire and crimp connections are on that rack over
there."
Worked fine, even if I didn't get the length exactly right. Lots left
over, if I can find it again.
Ronc
On Sun, 27 Dec 2009 11:25:16 -0600 Bruce Hislop <bruce@perthcomm.com>
writes:
>
>
> I'd say you have a poor connection supplying power to the headlights
> and the PO has connected the Tach to the power lead for the
> headlight switch. When you pull on the headlight switch, the load
> of the headlights pulls the voltage way down to near Zero volts
> because of a bad connection. Therefore, no headlights and no Tach.
> According to my Electrical diagram for 1976, the power to the
> Headlight switch comes from the main power terminal on the Horn
> Relay under the right front hood. The power for the turn signals
> come on a separate wire to the Bat bus bar in the fuse panel. The
> only common point is the main battery connection on the Horn relay,
> or the fusable link supplying the power to that point. However if it
> was the fusable link, the entire coach front would appear dead as it
> supplies all power to the dash, ign switch etc.
>
> BTW, has anyone ever had that fusable link go bad??
> --
> Bruce Hislop,
> S. Ontario Canada
> 77PB, 455
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=500&ppuser=1906
>
> _______________________________________________
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> List Information and Subscription Options:
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>
Ron & Linda Clark
1978 Eleganza II
North Plains, ORYGUN
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Ron & Linda Clark
North Plains, ORYGUN
78 Eleganza II
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