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| Re: [GMCnet] Extension cord to shore power [message #98208 is a reply to message #98200] |
Thu, 02 September 2010 11:11   |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Do you have 50 amp big cable with 4 conector in the plug or the 30 amp
with 3 connectors in the plug. The Adapter allow you to connect your
big coach cable to either an 30 amp plug( 50amp to 30 amp. Then you
have the 50 amp to 20 amp and 30 amp to 20 amp. If you have the 50
amp with 2 roof air you will be able to run only one roof air when
using the 30 amp adapter. When using the 20 amp adapter it is
possible but marginal to run the roof air but you may blow the park
breaker (20 amp) if you try to run anything else in the coach such as
the HW heater.
JR Wright
> How important is it to have a four conductor extension cord from
> shore power? The receptacle from the Onan is four conductor but
> there are several adapters stored with the cord.
> Robert McMahan
> 1977 Kingsley
>
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Extension cord to shore power [message #98236 is a reply to message #98200] |
Thu, 02 September 2010 14:26 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
Karma: 0
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Robert,
A couple of thoughts. The 4 wire cable supplies 117/240 power to the coach. If you have 2 rooftop AC units you should stay with a 4 wire cable. If this is for home use you'll need a 117/240 volt socket at the house as well. For single AC you do not need a 4 wire cable but need to use one heavy enough to carry the AC load without serious voltage drop.
The 4 wire cable is only a 4 wire cable when hooked up to a suitable 50A circuit. When connected to a 3 wire adaptor it becomes essentially a 3 wire cable as the 2 "hot" wires are jumpered together.
The 4 wire cable supplies 117/240 volts at 50 amps, the 3 wire supplies 117 volts at 30 amps.
Glenn
Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
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| Re: [GMCnet] Extension cord to shore power [message #98654 is a reply to message #98236] |
Sun, 05 September 2010 14:30 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Senior Member |
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Let me add a point I did not see mentioned.
If you have an extension cord that plugs into the OEM 50 amp plug set you have two concerns to keep in mind.
first---
The guage of the wire in the extension cord should be a large as you can afford or handle. If you use very small wire, like #14, your are already cutting your power and if the extension cord is long, say 50 feet, the resistance in that cord will probably keep the Air con from operating because of low voltage.
Voltage may look normal when plugged in with the Ext Cord and nothing running in the RV. But if you have some load on the rv appliances and you have a very small cord, your voltage will drop.
I would not go smaller than #10 gage for 20 feet and probably #8 for 50 foot.
SECOND---
there is another concern that will come up. It is the ext cord socket where the GMC plug will plug in. There never ever is really 100% contact to the spades for power transfer. The lacking connection will relate to you as more resistance. If you have a lot of resistance in the plug, even a heavy #10 cord will have trouble moving the needed current for your GMC.
ok, look at it this way, if the normal cord is not a problem but carrys a low resistance, and you add the ext cord and plug in the GMC plug to the ext cord socket, its like adding resistance or doubling or even tripling the length of your cord. Remember the longer the cord, the more resistance.
Just look at it this way, the more extension cords you use, the less power you will be able to get from the land line. If you keep turning things on you will eventually find the limit you are able to use in relation to the size of the cord, the length of the ext cord and how many plugs and sockets you are using to connect them.
Just thought I would mention that.
Gatsbys' CRUISER  08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
_
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| Re: [GMCnet] Extension cord to shore power [message #98707 is a reply to message #98654] |
Mon, 06 September 2010 04:05 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| Larry C wrote on Sun, 05 September 2010 12:30 |
Let me add a point I did not see mentioned.
If you have an extension cord that plugs into the OEM 50 amp plug set you have two concerns to keep in mind.
first---
The guage of the wire in the extension cord should be a large as you can afford or handle. If you use very small wire, like #14, your are already cutting your power and if the extension cord is long, say 50 feet, the resistance in that cord will probably keep the Air con from operating because of low voltage.
Voltage may look normal when plugged in with the Ext Cord and nothing running in the RV. But if you have some load on the rv appliances and you have a very small cord, your voltage will drop.
I would not go smaller than #10 gage for 20 feet and probably #8 for 50 foot. ....
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I use #8... sometimes hard to find.
If you are using a 50 amp cord, it is possible to rig up an adapter that allows you to use TWO 20 amp extension cords in PARALLEL. (Side by Side.) Dividing the load over two cords. (How well the division would be determined by the wiring in the coach breaker box.) Do not try and make one if you do not already understand what I am saying.
If plugged into the right circuits, it can give you a true 240v in the coach.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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