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| Shore Power question [message #255954] |
Sun, 20 July 2014 18:32  |
thorndike
Messages: 406
Registered: January 2011
Location: Conifer, Colorado
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I was looking at installing a new outlet in my garage to supply shore power to the GMC when it occured to me that right inside my garage door, I had an electric dryer. The dryer outlet is 240v 30a. I'd like to create an extension cord to utilize the dryer outlet instead of installing a new one. What I haven't seen in my manuals is the power requirements for the Onan. Is it 240v or 120v? If it is 240v are there any issues I should be aware of before connecting to the existing outlet?
Thanks!
Robert Peesel
1976 Royale 26'
Side Dry Bath
Conifer, Colorado
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| Re: Shore Power question [message #255957 is a reply to message #255954] |
Sun, 20 July 2014 19:09  |
A Hamilto
Messages: 4508
Registered: April 2011
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thorndike wrote on Sun, 20 July 2014 18:32I was looking at installing a new outlet in my garage to supply shore power to the GMC when it occured to me that right inside my garage door, I had an electric dryer. The dryer outlet is 240v 30a. I'd like to create an extension cord to utilize the dryer outlet instead of installing a new one. What I haven't seen in my manuals is the power requirements for the Onan. Is it 240v or 120v? If it is 240v are there any issues I should be aware of before connecting to the existing outlet?
Thanks! The Onan is out of the picture when you plug the OEM power cord into shore power.
If the dryer outlet is wired correctly (two hots, a neutral and ground), it will work the same as a shore power outlet at a campground, except...
To be safe and comply with code requirements, you will have to replace either the dryer outlet, or the breaker that feeds it, with a GFCI type.
To answer the question you were sort of asking, the OEM receptacle that is wired to the Onan is wired so that the same 120VAC appears on both of the "hot" leads. The Onan only outputs 120VAC. On 240VAC circuits, there are two 120VAC "hot" leads that are 180 degrees out-of-phase. Measure between either of the hots and neutral (or ground) and you get 120VAC. Measure between the two hots and you get 240VAC.
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| Re: Shore Power question [message #255959 is a reply to message #255957] |
Sun, 20 July 2014 19:28 |
thorndike
Messages: 406
Registered: January 2011
Location: Conifer, Colorado
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Duh. As soon as I saw your reply I realized how dumb I was being as I know that the Onan is out of the picture when on shore power. I was thinking about the A/C unit, the refrigerator and installing an inverter when I wrote the message. I guess I should think twice before hitting the send button!
I do have a bit more information for clarification. The ground plug on the GMC is 'U' shaped while the ground plug on the dryer plug is 'L' shaped. Is this going to cause an issue I should be aware of?
Robert Peesel
1976 Royale 26'
Side Dry Bath
Conifer, Colorado
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| Re: [GMCnet] Shore Power question [message #255961 is a reply to message #255957] |
Sun, 20 July 2014 19:27 |
k2gkk
Messages: 4452
Registered: November 2009
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Technically, the two lines are in the same single phase but at a given point are in opposite "polarity" to each other. The individual lines shift back and forth around the central neutral.
I have a separate 240 V (120-0-120) line from my house breaker box to feed my 1977 coach and
it works great!
Mac in OKC
Money Pit
Sent from my iPhone
On Jul 20, 2014, at 19:09, "A." wrote:
thorndike wrote on Sun, 20 July 2014 18:32
> I was looking at installing a new outlet in my garage to supply shore power to the GMC when it occured to me that right inside my garage door, I
> had an electric dryer. The dryer outlet is 240v 30a. I'd like to create an extension cord to utilize the dryer outlet instead of installing a new
> one. What I haven't seen in my manuals is the power requirements for the Onan. Is it 240v or 120v? If it is 240v are there any issues I should be
> aware of before connecting to the existing outlet?
>
> Thanks!
The Onan is out of the picture when you plug the OEM power cord into shore power.
If the dryer outlet is wired correctly (two hots, a neutral and ground), it will work the same as a shore power outlet at a campground, except...
To be safe and comply with code requirements, you will have to replace either the dryer outlet, or the breaker that feeds it, with a GFCI type.
To answer the question you were sort of asking, the OEM receptacle that is wired to the Onan is wired so that the same 120VAC appears on both of the
"hot" leads. The Onan only outputs 120VAC. On 240VAC circuits, there are two 120VAC "hot" leads that are 180 degrees out-of-phase. Measure between
either of the hots and neutral (or ground) and you get 120VAC. Measure between the two hots and you get 240VAC.
--
'73 23' Sequoia For Sale
'73 23' CanyonLands For Sale
Upper Alabama
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| Re: [GMCnet] Shore Power question [message #255962 is a reply to message #255961] |
Sun, 20 July 2014 19:29 |
k2gkk
Messages: 4452
Registered: November 2009
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Oops! 1976 coach!
Mac
Sent from my iPhone
On Jul 20, 2014, at 19:27, "D C _Mac_ Macdonald" wrote:
Technically, the two lines are in the same single phase but at a given point are in opposite "polarity" to each other. The individual lines shift back and forth around the central neutral.
I have a separate 240 V (120-0-120) line from my house breaker box to feed my 1977 coach and
it works great!
Mac in OKC
Money Pit
Sent from my iPhone
On Jul 20, 2014, at 19:09, "A." wrote:
thorndike wrote on Sun, 20 July 2014 18:32
> I was looking at installing a new outlet in my garage to supply shore power to the GMC when it occured to me that right inside my garage door, I
> had an electric dryer. The dryer outlet is 240v 30a. I'd like to create an extension cord to utilize the dryer outlet instead of installing a new
> one. What I haven't seen in my manuals is the power requirements for the Onan. Is it 240v or 120v? If it is 240v are there any issues I should be
> aware of before connecting to the existing outlet?
>
> Thanks!
The Onan is out of the picture when you plug the OEM power cord into shore power.
If the dryer outlet is wired correctly (two hots, a neutral and ground), it will work the same as a shore power outlet at a campground, except...
To be safe and comply with code requirements, you will have to replace either the dryer outlet, or the breaker that feeds it, with a GFCI type.
To answer the question you were sort of asking, the OEM receptacle that is wired to the Onan is wired so that the same 120VAC appears on both of the
"hot" leads. The Onan only outputs 120VAC. On 240VAC circuits, there are two 120VAC "hot" leads that are 180 degrees out-of-phase. Measure between
either of the hots and neutral (or ground) and you get 120VAC. Measure between the two hots and you get 240VAC.
--
'73 23' Sequoia For Sale
'73 23' CanyonLands For Sale
Upper Alabama
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| Re: Shore Power question [message #255963 is a reply to message #255954] |
Sun, 20 July 2014 19:33 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
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Not knowing what changes have been made to your coach over the years I can only comment on how AC was handled when the coach was built. Your generator, unless modified or changed, produces 110 volts. It is not affected by the 220 you will input from your dryer receptacle. The two sources are independent of one another. When you plug your power cord into the dryer receptacle the 220 from your house is split in your onboard breaker box into 2 separate 110 volt circuits that supply different parts of the coach, 220 volts is probably never used. When you plug your power cord into the onboard generator receptacle the 110 from the generator feeds both of those 110 volt circuits in your breaker box. When using AC from your dryer receptacle you will have two 110 volt, 30 amp circuits feeding the coach. When using the generator you will have one 110 volt circuit feeding both circuits with as many amps as the generator is capable of producing.
Answer your question?
Glenn.
Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
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| Re: Shore Power question [message #255964 is a reply to message #255954] |
Sun, 20 July 2014 20:10 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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thorndike wrote on Sun, 20 July 2014 19:32I was looking at installing a new outlet in my garage to supply shore power to the GMC when it occured to me that right inside my garage door, I had an electric dryer. The dryer outlet is 240v 30a. I'd like to create an extension cord to utilize the dryer outlet instead of installing a new one. What I haven't seen in my manuals is the power requirements for the Onan. Is it 240v or 120v? If it is 240v are there any issues I should be aware of before connecting to the existing outlet?
Thanks!
Robert,
I am tired. We just got home.
But when it comes to this sort of thing, read what three people here write. Those there would be:
Ken Henderson
Ken Burton
Bruce Hislop
And it a sincere pinch Maybe yours truly (in desperation only)
First, if you read the other groups on the web, you will know that three or for coaches or trailers a month get severely damage by just such a move.
A dryer outlet will destroy large portions of the value of your coach.
The difference is 5-30 to 14-50...
The dryer outlet is 6-30 That means 230V-30A
A TT-30 is a special outlet for trailers (TT) that is 120V (5) and 30 Amp (see 5-30)
14-50 (what your coach wants is 120-120 At 50 amp.
Tell any body working on this that the 14-50 out let is what you need.
If you try to make an adapter to the dryer outlet, have you insurance all paid up and the policy in you hand before you plug the coach in.......
Its late and I need a shower real bad, but we had a great weekend in Evart.
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: Shore Power question [message #255968 is a reply to message #255964] |
Sun, 20 July 2014 21:17 |
thorndike
Messages: 406
Registered: January 2011
Location: Conifer, Colorado
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Matt,
Thanks for the information.
It looks like I am going to have to run a dedicated 110v 30a circuit to the garage as my garage circuits are only 110v 20a.
Thanks for keeping my coach in one piece!
Bob
Robert Peesel
1976 Royale 26'
Side Dry Bath
Conifer, Colorado
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| Re: Shore Power question [message #255973 is a reply to message #255964] |
Sun, 20 July 2014 22:29 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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Matt Colie wrote on Sun, 20 July 2014 20:10Robert,
I am tired. We just got home.
But when it comes to this sort of thing, read what three people here write. Those there would be:
Ken Henderson
Ken Burton
Bruce Hislop
And it a sincere pinch Maybe yours truly (in desperation only)
First, if you read the other groups on the web, you will know that three or for coaches or trailers a month get severely damage by just such a move.
A dryer outlet will destroy large portions of the value of your coach.
The difference is 5-30 to 14-50...
The dryer outlet is 6-30 That means 230V-30A
A TT-30 is a special outlet for trailers (TT) that is 120V (5) and 30 Amp (see 5-30)
14-50 (what your coach wants is 120-120 At 50 amp.
Tell any body working on this that the 14-50 out let is what you need.
If you try to make an adapter to the dryer outlet, have you insurance all paid up and the policy in you hand before you plug the coach in.......
Its late and I need a shower real bad, but we had a great weekend in Evart.
Matt Matt makes a point. A three wire dryer outlet does not have a neutral, only two 120VAC hots that are 180 degrees out of phase, and a ground. The GFCI breaker I told you to install wouldn't work.
If you have a 3-wire dryer outlet, the ground would have to act as a neutral, and if it originates in a sub-panel, that can not only damage stuff, but is enormously dangerous.
A four-wire dryer outlet with four wires connected in it and four wires at the panel would be electrically identical to whatever an electrician would wire for shore power, except would need the GFCI breaker.
Once you get a GFCI breaker in place, it would work fine for an RV. I would just cobble up an adapter to get the GMC power cord (with the straight neutral conductor on the plug) connected to the 4-wire dryer receptacle (with the L-shaped neutral conductor).
I was posting with the understanding that your dryer outlet was 4-wire.
Is your dryer receptacle a 3-wire or 4-wire?
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| Re: Shore Power question [message #255979 is a reply to message #255975] |
Sun, 20 July 2014 22:40 |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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Just thought I would toss this in here to add to the confusion. My 1976 Royale is 30 amp service, not 50, and it is stock. The Onan is hard wired to the coach breaker panel, also stock. The AC from the shore power and Onan go to a pair of 30 amp breakers with an either/or connection, that is turning one on turns the other off.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Shore Power question [message #255980 is a reply to message #255979] |
Sun, 20 July 2014 22:45 |
thorndike
Messages: 406
Registered: January 2011
Location: Conifer, Colorado
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Otterwan,
That is exactly how mine is set up. Once I get a solid shore power source, I want to install an inverter to eliminate need to manually switch power sources at the circuit breaker.
Robert Peesel
1976 Royale 26'
Side Dry Bath
Conifer, Colorado
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| Re: [GMCnet] Shore Power question [message #255994 is a reply to message #255993] |
Mon, 21 July 2014 06:42 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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If, and only if, you wanted to only charge your batteries, and run the frig, and internal lights, you could use an adapter from a GFI'd house outlet. 15a should handle those tasks.
No A/C, start-up has too much draw.
JTWID.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Shore Power question [message #255999 is a reply to message #255954] |
Mon, 21 July 2014 08:18 |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
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Though it did take a bit of work to put it in, I love my 240 volt 50 amp RV outlet on the outside of my garage so I can simply plug the coach in when it's parked. One of the nicest upgrades I've done, and it does make it nice when I can run the AC to cool off the interior before taking on some remodeling projects on the coach.
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: [GMCnet] Shore Power question [message #256013 is a reply to message #255980] |
Mon, 21 July 2014 13:15 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Robert,
You may want to install an inverter, but be aware that most of them will
NOT do what you suggest: "eliminate need to manually switch power sources
at the circuit breaker." Most of them will only convert 12 VDC to 120
vac, giving
you a third source of the that 120 vac but doing NO switching among those 3.
There are some "inverters" that are really 3-function devices: Converter +
Inverter + Switch. Few GMCs are equipped with those because they
originally came with converters; most of us have incrementally added
inverters. A few of us lazier ones, like me, have then added the automatic
switches. The fact that you have a Coachment-built GMC with only 30A
service makes that addition easy. You can buy a "switch" for that purpose,
or you can do this:
http://www.gmcmhphotos.com/photos/g3484-automatic-120-vac-power-source-selection.html
HTH,
Ken H.
On Sun, Jul 20, 2014 at 11:45 PM, Robert Peesel wrote:
> Otterwan,
>
> That is exactly how mine is set up. Once I get a solid shore power
> source, I want to install an inverter to eliminate need to manually switch
> power
> sources at the circuit breaker.
>
>
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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] Shore Power question [message #256014 is a reply to message #256013] |
Mon, 21 July 2014 13:48 |
Guy Lopes
Messages: 499
Registered: April 2004
Location: Sacramento, CA
Karma: 3
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Senior Member |
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Ken,
I like your DIY switcher and plan to build one for my Birchaven. Rather than
fully automatic operation though, I would prefer to be able to select the
source. I'm thinking of installing a sub panel, near my systems panel, that
would have three indicator lights to show that a source is available, three
push buttons switches to select that source and three indicator lights
indicating that source is providing power.
In my mind I can kind of see how this could be done, but being the cautious
type, I have to ask the expert... can you describe to this electronics
newbie how I could achieve this?
Thank you,
Guy Lopes
76 Birchaven "Orion"
Sacramento, CA
W6TOL
www.GMC-Guy.com
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Ken Henderson
Sent: Monday, July 21, 2014 11:16 AM
To: gmclist
Subject: Re: [GMCnet] Shore Power question
Robert,
You may want to install an inverter, but be aware that most of them will NOT
do what you suggest: "eliminate need to manually switch power sources at
the circuit breaker." Most of them will only convert 12 VDC to 120 vac,
giving you a third source of the that 120 vac but doing NO switching among
those 3.
There are some "inverters" that are really 3-function devices: Converter +
Inverter + Switch. Few GMCs are equipped with those because they originally
came with converters; most of us have incrementally added inverters. A few
of us lazier ones, like me, have then added the automatic switches. The
fact that you have a Coachment-built GMC with only 30A service makes that
addition easy. You can buy a "switch" for that purpose, or you can do this:
http://www.gmcmhphotos.com/photos/g3484-automatic-120-vac-power-source-selec
tion.html
HTH,
Ken H.
On Sun, Jul 20, 2014 at 11:45 PM, Robert Peesel wrote:
> Otterwan,
>
> That is exactly how mine is set up. Once I get a solid shore power
> source, I want to install an inverter to eliminate need to manually
> switch power sources at the circuit breaker.
>
>
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GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Guy Lopes
76 Birchaven "Orion"
Sacramento, CA
W6TOL
www.GMC-Guy.com
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