Home » Public Forums » GMCnet » Check your wiring
| Check your wiring [message #340662] |
Tue, 05 February 2019 19:06  |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
Karma: 7
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Senior Member |
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Here is a friendly public service announcement - check your wiring! For chafing, corrosion, previous owner or mechanic mis-wiring, any and ALL of it!
I'm replacing my Onan which was missing several key pieces when I bought the coach, so I'm going through pretty intently.
So, Coachmen ran heavy and not so heavy 12 volt wiring UNDER the coach. OK. But it's just winding through the frame with no retention straps, protective cladding, or anything. This coach has engine and house batteries up front, and a third Onan battery in rear (which has not been there since I've owned it). The main house trunk line (as shown in Coachmen wiring diagram on bdub site) goes from charger and fuse panels (interior over passenger rear tires), out the floor and under the back to the driver side with a "Y" at the generator battery and then up front. Factory manual shows a 50 amp breaker at the rear "Y", but it only protects the main line from the generator battery, and not the line itself from the charger. That seems wrong to me, but is the factory setup. Also there was a 50 amp GMC breaker up at the front from Coachmen factory. So there were originally breakers near each battery, but not the charger...?
http://www.bdub.net/wirediagrams/1977_Coachmen_26RB_Electrical_and_Plumbing_Drawings.pdf
Page 5 shows this "Y"
So here was my potential problem: 1. the 8 gauge main house wire chafed through more than an inch of sheathing at the 90 degree turn near the generator (bad enough by itself) and 2. The GMC factory 50 amp breaker up front had been upgraded to a modern thermal breaker - nice right? Not. The house wire to the back had been mounted on the same side of the breaker as the battery! The 12 volt feed to the fridge and the water heater were the only two lines being protected by the 50 amp breaker. (Do all Coachmen have this odd fridge/heater separate fused lines to the appliances?)
So please check your wiring for integrity, proper routing and general good practices for electrical load and mechanical stresses. Understand the original diagrams and intent of the engineers, and verify all upgrades and additions have good integrity - especially on high amperage lines! I have looked at that inherited miswired breaker for over a year, not until I was really learning the system did I realize the flaw.
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
[Updated on: Tue, 05 February 2019 19:12] Report message to a moderator |
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| Re: [GMCnet] Check your wiring [message #340663 is a reply to message #340662] |
Tue, 05 February 2019 19:32  |
JerryW
Messages: 256
Registered: August 2018
Karma: 1
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Senior Member |
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You say “Factory” several times. But you don’t really say GM or Coachmen. I’m sure you realize that your motorhome left the GM factory as a Transmide and that after Coachmen added the Onan, battery and house wiring it left their Factory as a Royale.
So much of your warning doesn’t affect most of us — only Royale owners!
Coachmen did a great job with the cabinetry but norms as well on wiring and plumbing.
Emery Stora
> On Feb 5, 2019, at 6:06 PM, Tyler wrote:
>
> Here is a friendly public service announcement - check your wiring! For chafing, corrosion, previous owner or mechanic mis-wiring, any and ALL of it!
>
>
> I'm replacing my Onan which was missing several key pieces when I bought the coach, so I'm going through pretty intently.
>
> So, Coachmen ran heavy and not so heavy 12 volt wiring UNDER the coach. OK. But it's just winding through the frame with no retention straps,
> protective cladding, or anything. This coach has engine and house batteries up front, and a third Onan battery in rear (which has not been there since
> I've owned it). The main house trunk line (as shown in Coachmen wiring diagram on bdub site) goes from charger and fuse panels (interior over
> passenger rear tires), out the floor and under the back to the driver side with a "Y" at the generator battery and then up front. Factory manual shows
> a 50 amp breaker at the rear "Y", but it only protects the main line from the generator battery, and not the line itself from the charger. That seems
> wrong to me, but is the factory setup. Also there was a 50 amp GMC breaker up at the front from Coachmen factory. So there were originally breakers
> near each battery, but not the charger...?
>
> So here was my potential problem: 1. the 8 gauge main house wire chafed through more than an inch of sheathing at the 90 degree turn near the
> generator (bad enough by itself) and 2. The GMC factory 50 amp breaker up front had been upgraded to a modern thermal breaker - nice right? Not. The
> house wire to the back had been mounted on the same side of the breaker as the battery! The 12 volt feed to the fridge and the water heater were the
> only two lines being protected by the 50 amp breaker. (Do all Coachmen have this odd fridge/heater separate fused lines to the appliances?)
>
> So please check your wiring for integrity, proper routing and general good practices for electrical load and mechanical stresses. Understand the
> original diagrams and intent of the engineers, and verify all upgrades and additions have good integrity - especially on high amperage lines! I have
> looked at that inherited miswired breaker for over a year, not until I was really learning the system did I realize the flaw.
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
>
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| Re: Check your wiring [message #340664 is a reply to message #340662] |
Tue, 05 February 2019 21:32 |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
Karma: 7
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Senior Member |
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Yep, the two factories kind of mix in my account a bit...
However, my reminder hopefully registers with everyone! Five years ago I had to clad my "from GMC" Glenbrook's 2 gauge front to back wiring in the section where it runs across the radiator support bracket. The insulation had come completely off in several spots and could be rubbed off by hand in a few more. My previous example and a few questions were Coachmen specific, but 40 year old wiring (with and without modifications) needs an in depth checking over as part of regular maintenance.
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
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| Re: [GMCnet] Check your wiring [message #340682 is a reply to message #340662] |
Wed, 06 February 2019 11:04 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Senior Member |
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I added a 50-amp magnetic breaker to the 12-volt house power line at the
12-volt panel under the fridge. It’s big enough for the charger. I also
mounted an 80-amp thermal breaker adjacent to the boost solenoid up front,
near the house battery on my ‘73. Branches that can turn into welding rods
need protection on both ends against a catastrophic short.
Rick “who once rana screw into that wire” Denney
On Tue, Feb 5, 2019 at 8:07 PM Tyler wrote:
> Here is a friendly public service announcement - check your wiring! For
> chafing, corrosion, previous owner or mechanic mis-wiring, any and ALL of
> it!
>
>
> I'm replacing my Onan which was missing several key pieces when I bought
> the coach, so I'm going through pretty intently.
>
> So, Coachmen ran heavy and not so heavy 12 volt wiring UNDER the coach.
> OK. But it's just winding through the frame with no retention straps,
> protective cladding, or anything. This coach has engine and house
> batteries up front, and a third Onan battery in rear (which has not been
> there since
> I've owned it). The main house trunk line (as shown in Coachmen wiring
> diagram on bdub site) goes from charger and fuse panels (interior over
> passenger rear tires), out the floor and under the back to the driver side
> with a "Y" at the generator battery and then up front. Factory manual shows
> a 50 amp breaker at the rear "Y", but it only protects the main line from
> the generator battery, and not the line itself from the charger. That seems
> wrong to me, but is the factory setup. Also there was a 50 amp GMC breaker
> up at the front from Coachmen factory. So there were originally breakers
> near each battery, but not the charger...?
>
> So here was my potential problem: 1. the 8 gauge main house wire chafed
> through more than an inch of sheathing at the 90 degree turn near the
> generator (bad enough by itself) and 2. The GMC factory 50 amp breaker up
> front had been upgraded to a modern thermal breaker - nice right? Not. The
> house wire to the back had been mounted on the same side of the breaker as
> the battery! The 12 volt feed to the fridge and the water heater were the
> only two lines being protected by the 50 amp breaker. (Do all Coachmen
> have this odd fridge/heater separate fused lines to the appliances?)
>
> So please check your wiring for integrity, proper routing and general good
> practices for electrical load and mechanical stresses. Understand the
> original diagrams and intent of the engineers, and verify all upgrades and
> additions have good integrity - especially on high amperage lines! I have
> looked at that inherited miswired breaker for over a year, not until I was
> really learning the system did I realize the flaw.
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
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