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Home » Public Forums » GMCnet » [GMCnet] Lost 30A service
[GMCnet] Lost 30A service [message #333844] Fri, 22 June 2018 09:31 Go to next message
glwgmc is currently offline  glwgmc   United States
Messages: 1014
Registered: June 2004
Karma: 10
Senior Member
Deb,

While,you are rooting around in that box take the time to carefully diagram how your coach is wired. Being a GM finished coach there should be no surprises unless a P.O. changed things. Some of the upfitter finished coaches back fed breakers to accomplish a transfer switch function going from gen to shore,power. Most GM finished coaches simply had you move the power line from the RV post receptacle to a gen receptacle to do that. Most GM finished coaches used 50 amp shore power plugs and wire sizes while many upfitters used 30 amp shore power plugs and wire sizes.

Coachman - Royale and Birchhaven - had 30 amp incoming shore power lines and only allowed the front air conditioner to operate off shore power. To run the rear air conditioner you had to run the generator. After 40 plus years of owners, you want to know for sure what you have.

The AC lines running to each Air conditioner should be 12 gage two conductor wire with a ground as the original air conditioners consumed more power than most new ones do so needed that 12 ga wire to safely carry the starting amp load. A 12 ga AC line can handle up to 20 amps while a 14 ga AC line can only handle 15 amps or less depending on the length of the run and corrosion on connectors along the way. A 10 ga AC line can handle up,to,30 amps while an 8 ga AC line is required to handle 50 amps. Note, true marine wire can handle more amps at a given size than their AC line cousins noted above, but true marine wire is much more expensive and rarely seen in RVs.

Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com
—————
Message: 9
Date: Wed, 20 Jun 2018 18:55:00 -0600
From: Deb McWade
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Lost 30A service
Message-ID:
Content-Type: text/plain; charset="utf-8"

:uhoh: Oich! OK - smack me and screw my head back on. Put my glasses on (the READING ones) and actually READ the breaker switches - ON is toward the
centre of the box, not toward the bottom.
So.... flipped the bottom breakers switches UP and guess what!? Everything is fine. :blush: So, Although I DID fry the 50 to 30A dog-bone,
everything else is fine and runs perfectly on the 50A connector.

I think I'm going to go to bed now and start the day over!
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
——————-
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Jerry & Sharon Work
78 Royale
Kerby, OR
Re: [GMCnet] Lost 30A service [message #333909 is a reply to message #333844] Sat, 23 June 2018 18:47 Go to previous messageGo to next message
thesmith is currently offline  thesmith   United States
Messages: 589
Registered: February 2015
Location: Cary, NC
Karma: 6
Senior Member
Pretty sure my 78 center kitchen Royale runs both ac from shore power or from genny.....it's got 50a cable hard wired in....which you plug into a socket on the floor when you want to run from the genny. No change over switch.

Pete.



glwgmc wrote on Fri, 22 June 2018 10:31
Deb,

While,you are rooting around in that box take the time to carefully diagram how your coach is wired. Being a GM finished coach there should be no surprises unless a P.O. changed things. Some of the upfitter finished coaches back fed breakers to accomplish a transfer switch function going from gen to shore,power. Most GM finished coaches simply had you move the power line from the RV post receptacle to a gen receptacle to do that. Most GM finished coaches used 50 amp shore power plugs and wire sizes while many upfitters used 30 amp shore power plugs and wire sizes.

Coachman - Royale and Birchhaven - had 30 amp incoming shore power lines and only allowed the front air conditioner to operate off shore power. To run the rear air conditioner you had to run the generator. After 40 plus years of owners, you want to know for sure what you have.

The AC lines running to each Air conditioner should be 12 gage two conductor wire with a ground as the original air conditioners consumed more power than most new ones do so needed that 12 ga wire to safely carry the starting amp load. A 12 ga AC line can handle up to 20 amps while a 14 ga AC line can only handle 15 amps or less depending on the length of the run and corrosion on connectors along the way. A 10 ga AC line can handle up,to,30 amps while an 8 ga AC line is required to handle 50 amps. Note, true marine wire can handle more amps at a given size than their AC line cousins noted above, but true marine wire is much more expensive and rarely seen in RVs.

Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com
----------
Message: 9
Date: Wed, 20 Jun 2018 18:55:00 -0600
From: Deb McWade
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Lost 30A service
Message-ID:
Content-Type: text/plain; charset="utf-8"

Uh Oh Oich! OK - smack me and screw my head back on. Put my glasses on (the READING ones) and actually READ the breaker switches - ON is toward the
centre of the box, not toward the bottom.
So.... flipped the bottom breakers switches UP and guess what!? Everything is fine. Embarassed So, Although I DID fry the 50 to 30A dog-bone,
everything else is fine and runs perfectly on the 50A connector.

I think I'm going to go to bed now and start the day over!
--
Deb McWade
Logan Lake, BC, CAN
"Li'l Sister"
'77 Kingsley, 403, EBL EFI;
TZE167V101404
It's Bigger on the Inside!
-------------
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GMCnet mailing list
Unsubscribe or Change List Options:
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Cary, NC 1978 Center Kitchen Royale.
Re: [GMCnet] Lost 30A service [message #333945 is a reply to message #333844] Sun, 24 June 2018 18:35 Go to previous message
Hal StClair   United States
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
Senior Member
Actually, just to 'pick a nit', the 15 amp wire wouldn't support the running load of the AC. 80% of #14 NM cable is 12 amps, the most permitted by the NEC. The over current device (breaker) can be as much as 225% of the conductors ampacity or 33.75 amps on #14 wire. AC systems fall under different rules (NEC article 440) Very Happy

Hal,

Slow recovering retired electrician/inspector


"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane." 1977 Royale 101348, 1977 Royale 101586, Diesel powered, 1974 Eagle Bus 45',w/slideout, Rio Rancho, NM
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