Home » Public Forums » GMCnet » 30 or 50 amp service
| 30 or 50 amp service [message #151869] |
Tue, 06 December 2011 08:33  |
skip2
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
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My 74 grandcanyons has a 50 amp service cable for shore power when using the 30 amp adapter at home I can run both AC,s with no problem and no signs of the adapter wire getting warm. Was 50 amp the standard service or did someone put on a 50 amp cable. It's sometimes is a real challenge to roll up in the compartment especially if it a little cool. Thanks,
Skip
74 Canyon Lands, FiTech,
3.7 FD LSD, Manny Tranny,
Springfield Distributor,
2001 Chevy Tracker Ragtop Towd
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| Re: 30 or 50 amp service [message #151876 is a reply to message #151869] |
Tue, 06 December 2011 08:53  |
jknezek
Messages: 1057
Registered: December 2007
Karma: 5
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50 amp was standard on the GMC. Since the coaches were usually wired for 2 ACs plus the electric fridge and electric water heater, and the fact that it was top of the line luxury at production, 50 amp made sense.
You may not need 50 amp, especially with two modern AC, but you can overload a 30 amp circuit using a single AC, a microwave, the refrigerator, the water heater, a tv and some lights. There are dozens of configurations that will put you over a 30 amp circuit given today's various gadgets and gizmos. AC and coffee machine or AC and hairdryer are two very common baselines that when you add just a bit more will blow 30 amps.
That being said, 30 amp is certainly doable. We don't book 50 amp sites except during the middle of summer when the ACs are going full blast.
Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
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| Re: 30 or 50 amp service [message #151889 is a reply to message #151869] |
Tue, 06 December 2011 09:47 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Hi Skip
I understand the problem. I cut my 50 amp cord to 2 feet and put new ends on both pieces. (the 2foot pigtail allows me to plug into the generator outlet) The female end for the new extension is a metal box type because I could not find a cord type. When I need it, the end will fit in the compartment out of the weather. I Store the 50 amp cord until I need 50 amp service. (which so far has been never) Otherwise I use a 30 amp cord with a 50 amp adaptor. (which also fits in the compartment) The 30 Amp cord is a whole lot more flexible and can be stored in other places. This allows me to store water and electrical adaptors and accessories int the compartment. Best regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] 30 or 50 amp service [message #151903 is a reply to message #151891] |
Tue, 06 December 2011 11:03 |
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rssbob wrote on Tue, 06 December 2011 07:52]Here is one way to deal with this. As already stated by Bruce and John.
Bob, that is a cool way to deal w/this problem; it's on my bucket list. (Along with many others!)
geo groth '73 260 Sequoia
Carson City Nevada 89703
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| Re: [GMCnet] 30 or 50 amp service [message #151919 is a reply to message #151869] |
Tue, 06 December 2011 14:29 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Skip,
Everyone's given you work-arounds. Here's another, which I don't need on
my X-Birchaven with a single A/C: My '90 Airstream Land Yacht had two
A/C's and only a 30A service cord, as was common back the, despite the
GMC's 40A cable. Also common then was the use of a switch, sometimes
manual, sometimes automatic, to select one or the other of the A/C's. One
of the more sophisticated automatic switches, for example, would allow both
A/C's to run, but they could not start simultaneously. Mine had a manual
switch.
Since we needed to run both A/C's in GA & our destinations, I completely
isolated one of the A/C's from everything else in the coach. With it
powered from a small single-breaker box, via a 10 gauge, 20A cord, I could
plug the 30A cord into the power pole's 30A socket, and the 20A cord into
the power pole's 15A socket and run everything with no problem. Most power
poles, even in those days had both sockets. If we didn't need both A/C, I
didn't bother with the 20A cord.
For those locations where 50A was available (sometimes ONLY), I installed
15A and 30A sockets in a plastic tool box with a 5' 50A pigtail. When
available, I used the 50A outlet and that adapter box because it had better
sockets than most power poles. Closing the box lid provided weather
protection. I still use that to support visitors who need a 30A connection
where I have only a 50A socket here at home.
JWID, HTH,
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Tue, Dec 6, 2011 at 9:33 AM, Skip Hartline <skiphartline@aol.com> wrote:
>
>
> My 74 grandcanyons has a 50 amp service cable for shore power when using
> the 30 amp adapter at home I can run both AC,s with no problem and no signs
> of the adapter wire getting warm. Was 50 amp the standard service or did
> someone put on a 50 amp cable. It's sometimes is a real challenge to roll
> up in the compartment especially if it a little cool. Thanks,
> Skip
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] 30 or 50 amp service [message #151933 is a reply to message #151903] |
Tue, 06 December 2011 17:22 |
rssbob
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
Karma: 0
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Thanks for the Kudos George.
On Dec 6, 2011, at 9:03 AM, George Groth wrote:
>
>
> rssbob wrote on Tue, 06 December 2011 07:52]Here is one way to deal with this. As already stated by Bruce and John.
>
> Bob, that is a cool way to deal w/this problem; it's on my bucket list. (Along with many others!)
> --
> geo groth '73 260 Sequoia
> Carson City Nevada 89703
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Bob Sobrito
78 Palm Beach
La Mesa, Ca
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| Re: 30 or 50 amp service [message #152016 is a reply to message #151869] |
Wed, 07 December 2011 06:36 |
skip2
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
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Thanks for all the inputs and ideals, glad to see I wasn't the only on that didn't like the big cable issue. I don't see how it can get rolled up in some of the colder areas. I'm in the middle of Florida and I time rolling it up after it sets in the sun for a few hours. If it drops to below 70 here won't even plug into shore power in the drive because I know I'll have to roll it up. Thanks Again.
Skip
74 Canyon Lands, FiTech,
3.7 FD LSD, Manny Tranny,
Springfield Distributor,
2001 Chevy Tracker Ragtop Towd
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| Re: [GMCnet] 30 or 50 amp service [message #152060 is a reply to message #152053] |
Wed, 07 December 2011 12:38 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| emerystora wrote on Wed, 07 December 2011 12:52 |
On Dec 7, 2011, at 5:36 AM, Skip Hartline wrote:
> Thanks for all the inputs and ideals, glad to see I wasn't the only on that didn't like the big cable issue. I don't see how it can get rolled up in some of the colder areas. I'm in the middle of Florida and I time rolling it up after it sets in the sun for a few hours. If it drops to below 70 here won't even plug into shore power in the drive because I know I'll have to roll it up. Thanks Again.
> Skip
Its probably all in how you try to roll it. I have rolled it in with below zero weather.
I push the cord against the back of the box and then rotate it in a loop and push it against the front of the box and then the back, etc.
It really goes in quite easily. See me at a GMCMI convention some time and I will demonstrate it.
Emery Stora
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Skip,
I'm with Emery here.
I have no trouble flaking the cable in the locker. In fact, when it is stowed, I can put the 5-30P (30 amp straight blade) and the 5l-30P (30amp twistlock for boat yards) in the middle of the coil.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] 30 or 50 amp service [message #152062 is a reply to message #151927] |
Wed, 07 December 2011 12:42 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Senior Member |
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On Tue, Dec 6, 2011 at 5:37 PM, D C *Mac* Macdonald <k2gkk@hotmail.com>wrote:
>
> I had an electrician install both 50A (120-0-120 V) and
> 30A (120 V) standard outlets on the side of my garage.
> The 50A has the split (with center neutral) 240V AC
> on it and the GMC seems to not care. I don't know if
> the two A/C units are wired to use opposite sides, but
> everything seems to work okay.
>
The two circuits in a factory GMC are completely independent. They can be
run in phase or out of phase with no issue, as long as nobody cross-wires
the circuits.
You can adapt a 50-amp cord to plug into a 30-amp supply--it just feeds
both hot prongs on the 50-amp connector from the same hot prong on the
30-amp connector. In that case, the two circuits would be in phase.
You cannot adapt a 50-amp supply to a 30-amp cord, without breaking it out
into two different receptacles as Ken did. They will likely be out of phase
when using a park receptacle.
One aspect of the 120-volt, 50-amp application is that the independent
circuits in the coach, being in phase, return onto the common neutral the
full current used by both separate circuits added together. So, a 50-amp
cable might feed a separate 20-amp circuit out of each hot prong, but it
will carry up to 40 amps on the neutral return path. In household 240VAC
applications, the neutral is usually zero voltage because one 240-volt
appliance is using both hots, and the neutral is therefore carrying two
equal but out-of-phase currents. Being out of phase, the voltage cancels
out. (In effect, the return is provided by the opposite hot, not by the
neutral.) This matters because those pigtails that folks have used are
designed for 240VAC appliances that will have a zero neutral, and those
pigtails often have big conductors for the hots and something nominally
small for the neutral. The first pigtail I used was #8 for the hots and #10
for the neutral return. #8 is adequate for 40 amps and overkill for 20
amps. But #10 is too small for a 40-amp return. I replaced it with a
pigtail that I had to order specially with #8 conductors on all positions
(even including the safety ground). I had to order it--nothing like that
was available in the home stores.
Rick "who probably never got close to the 40 amps" Denney
--
'73 230 "Jaws"
Northern Virginia
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| Re: [GMCnet] 30 or 50 amp service [message #152076 is a reply to message #152062] |
Wed, 07 December 2011 16:32 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Just a reminder. There is ONLY ONE PHASE in our
120-0-120 (240V) systems. L1 and L2 are just halves
of the single phase 240V power line. They are derived
from a center-tapped step-down transformer fed by a
much higher high voltage, one phase, feeder line.
Marinco makes adaptors to go from a 50A 120-0-120
(240V) connector to use just half of that to feed a
30A 120V connector.
The only time when this doesn't really work is when
the boat or RV has some appliances/devices that are
operated from an actual 240V single phase line.
In those cases, you just can't use the 240V device.
* * * * * * * * * * *
* 73 - Mac, K2GKK/5 *
* k2gkk@hotmail.com *
* (Since 30 Nov 53) *
* Oklahoma City, OK *
* USAF, Ret (61-81) *
* * * * * * * * * * *
> Date: Wed, 7 Dec 2011 13:42:40 -0500
> From: rwdenney@gmail.com
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] 30 or 50 amp service
>
> On Tue, Dec 6, 2011 at 5:37 PM, D C *Mac* Macdonald <k2gkk@hotmail.com>wrote:
>
> >
> > I had an electrician install both 50A (120-0-120 V) and
> > 30A (120 V) standard outlets on the side of my garage.
> > The 50A has the split (with center neutral) 240V AC
> > on it and the GMC seems to not care. I don't know if
> > the two A/C units are wired to use opposite sides, but
> > everything seems to work okay.
> >
>
> The two circuits in a factory GMC are completely independent. They can be
> run in phase or out of phase with no issue, as long as nobody cross-wires
> the circuits.
>
> You can adapt a 50-amp cord to plug into a 30-amp supply--it just feeds
> both hot prongs on the 50-amp connector from the same hot prong on the
> 30-amp connector. In that case, the two circuits would be in phase.
>
> You cannot adapt a 50-amp supply to a 30-amp cord, without breaking it out
> into two different receptacles as Ken did. They will likely be out of phase
> when using a park receptacle.
>
> One aspect of the 120-volt, 50-amp application is that the independent
> circuits in the coach, being in phase, return onto the common neutral the
> full current used by both separate circuits added together. So, a 50-amp
> cable might feed a separate 20-amp circuit out of each hot prong, but it
> will carry up to 40 amps on the neutral return path. In household 240VAC
> applications, the neutral is usually zero voltage because one 240-volt
> appliance is using both hots, and the neutral is therefore carrying two
> equal but out-of-phase currents. Being out of phase, the voltage cancels
> out. (In effect, the return is provided by the opposite hot, not by the
> neutral.) This matters because those pigtails that folks have used are
> designed for 240VAC appliances that will have a zero neutral, and those
> pigtails often have big conductors for the hots and something nominally
> small for the neutral. The first pigtail I used was #8 for the hots and #10
> for the neutral return. #8 is adequate for 40 amps and overkill for 20
> amps. But #10 is too small for a 40-amp return. I replaced it with a
> pigtail that I had to order specially with #8 conductors on all positions
> (even including the safety ground). I had to order it--nothing like that
> was available in the home stores.
>
> Rick "who probably never got close to the 40 amps" Denney
>
> --
> '73 230 "Jaws"
> Northern Virginia
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| Re: [GMCnet] 30 or 50 amp service [message #152082 is a reply to message #152053] |
Wed, 07 December 2011 17:21 |
Chuck Garton
Messages: 54
Registered: June 2006
Karma: 0
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Member |
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I have owned 2 coaches since 1977. 1) 1974 Sequoia 26', and 2) 1977
Kingsley 455. Both had the standard GMC interior and 50 amp power
cords. the 1974 power cord was much harder to roll up in cool weather
than the 1977 power cord. The parts manual barely mentions the power
cord and lists no part numbers.
Chuck Garton
Ridgecrest, CA
On Wed, Dec 7, 2011 at 9:52 AM, Emery Stora <emerystora@mac.com> wrote:
>
> On Dec 7, 2011, at 5:36 AM, Skip Hartline wrote:
>
>>
>>
>> Thanks for all the inputs and ideals, glad to see I wasn't the only on that didn't like the big cable issue. I don't see how it can get rolled up in some of the colder areas. I'm in the middle of Florida and I time rolling it up after it sets in the sun for a few hours. If it drops to below 70 here won't even plug into shore power in the drive because I know I'll have to roll it up. Thanks Again.
>> Skip
>
> Its probably all in how you try to roll it. I have rolled it in with below zero weather.
>
> I push the cord against the back of the box and then rotate it in a loop and push it against the front of the box and then the back, etc.
> It really goes in quite easily. See me at a GMCMI convention some time and I will demonstrate it.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
>
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