Home » Public Forums » GMCnet » Electrical Questions
| Electrical Questions [message #201441] |
Tue, 12 March 2013 19:49  |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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The CFO has me converting the old laundry closet in the kitchen into a pantry. The laundry room is in what used to be the garage - it all happened before we bought the house.
The 30A dryer breaker for the old laundry closet is avaiable, and the project involves opening up one of the walls where the wire needs to run.
So I am going to run the wire for a 30A shore power point in the course of the pantry project.
I was looking on line for wire sizes and voltage drop over distance and I am kind of torn on wire size/type.
The length is going to be about 25 feet. I think I could skrimp and use 10AWG wire, but for the price difference I don't mind using 8AWG.
The closest place to get stuff like that is the local Home Depot, and they only have 8/3 w/ground in stranded wire. Is that what I am supposed to use, or does someone sell solid 8/3 w/g wire, and would that would be better?
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| Re: Electrical Questions [message #201488 is a reply to message #201441] |
Wed, 13 March 2013 02:02  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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The normal wire for 30 amp service is 10 gauge. Stranded or solid, both will work. Most people prefer stranded. My problem is I worked as an electrician in both the industrial and commercial / residential areas. The rules and recommendations are different between the two. In the industrial environment we use to run 30 amps on 12 gauge wire.
At 25 feet you do not have to worry about any meaningful voltage drop and any of those 3 gauges would work. You will not hurt anything using 8 gauge wire. It is rated for 45 amps. I would use 10 gauge. I would not recommend 12 as it does not meet residential code.
Note: if pulling individual conductors, the safety (green wire) ground can be one gauge smaller and still meet code.
I'm assuming you are running 30 amp 240 volt service. If you are attaching to an existing dryer connection you may be missing the white wire (neutral) at that plug. If so, you will have to pull the new wire all the way back to the distribution panel / circuit breaker box.
Here is a basic ampacity chart. They did not get into distances and other variables in this chart.
http://www.cerrowire.com/ampacity-charts
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Electrical Questions [message #201507 is a reply to message #201441] |
Wed, 13 March 2013 07:40 |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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I am a licensed electrician, inside your home, use solid, the insulation is rated for non-accessible areas (inside walls, etc) the stranded usually coded SJ (service Jacket) is meant for power cords, this is what you will use to make your cord to plug in to your coach. 10AWG is for that distance is fine. Heed Ken's comment about the 240V service, your dyer, depending on age of installation may be a 3 wire or 4 wire service 3 wire is 2 hots and a ground (one hot from each phase) the 4 wire will have 2 hots, ground and neutral. Your coach needs 120V. so do not wire it the same as residential. You only need 1 of the hot legs, you will need to replace the 2 pole circuit breaker with a single pole 30A.
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
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| Re: Electrical Questions [message #201511 is a reply to message #201507] |
Wed, 13 March 2013 08:12 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Sean,
Some GMC's are wired for 240 volt with a good neutral, others are wired for wired for 120v 30 amp service. I assumed he was wanting to wire for 240 volt service but only install a 30 amp double pole breaker and 10 gauge wire to support that feed.
Both of us are correct at this point until we find out which GMC plug type and service he is trying to match.
Let's see what he is really trying to support.
Let's discuss this solid vs. stranded. I always used solid in residential and stranded in commercial buildings. When I worked in the industrial environment everything was also stranded.
Why are you recommending solid? I'm not saying you are wrong. I'm just trying to understand if it is a preference or a code thing that I do not remember.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Electrical Questions [message #201526 is a reply to message #201507] |
Wed, 13 March 2013 08:59 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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My 76 ex Palm Beach has the 6 kW Onan. Its output
is ~120 VAC. However, the single output is wired
to both L1 and L2 of the 240V (center tap neutral)
50A style 4-wire power receptacle. The matching
4-wire power plug goes to a double pole circuit
breaker. This allows running the two A/C units
on separate circuits (L1 and L2). I'm reasonably
certain that is the manner in which MOST of
the coaches using the 6 kW Onan are wired.
This is NOT in agreement with the advice below!
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
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> To: gmclist@temp.gmcnet.org
> From: fiatkidd@yahoo.com
> Date: Wed, 13 Mar 2013 07:40:37 -0500
> Subject: Re: [GMCnet] Electrical Questions
>
> I am a licensed electrician, inside your home, use solid, the insulation is rated for non-accessible areas (inside walls, etc) the stranded usually coded SJ (service Jacket) is meant for power cords, this is what you will use to make your cord to plug in to your coach. 10AWG is for that distance is fine. Heed Ken's comment about the 240V service, your dyer, depending on age of installation may be a 3 wire or 4 wire service 3 wire is 2 hots and a ground (one hot from each phase) the 4 wire will have 2 hots, ground and neutral. Your coach needs 120V. so do not wire it the same as residential. You only need 1 of the hot legs, you will need to replace the 2 pole circuit breaker with a single pole 30A.
> --
> 73 Ex-Canyon Lands 26' #317 "Oliver"
> Hubler 1-Ton, soon to have quadrareactiondisc rear.
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| Re: Electrical Questions [message #201527 is a reply to message #201441] |
Wed, 13 March 2013 09:05 |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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Senior Member |
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I should point out, never run solid conductor or cable in conduit, unless it is to protect it from a direct burial to surface installation (type UF) cable.
For all non laymen, conductor is just one wire, cable is an "assembly" of 2 or more wires in a protective covering...99% of residential including your service entrance cable at your meter is "cable" i.e.: romex- commercial name of type NM (non metallic cable)
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
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| Re: Electrical Questions [message #201530 is a reply to message #201441] |
Wed, 13 March 2013 09:12 |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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Senior Member |
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Mac, you are absolutely correct with your 50A service, however I need to point out that if you use a 2pole breaker to feed this service your potential is 240V phase to phase.
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
[Updated on: Wed, 13 March 2013 10:01] Report message to a moderator |
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| Re: Electrical Questions [message #201534 is a reply to message #201524] |
Wed, 13 March 2013 09:21 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| SeanKidd wrote on Wed, 13 March 2013 09:57 |
I read his post as adding residential wiring for shore power. I've never seen stranded "cable" in non metallic sheathed insulation (type NM) most commercial/industrial require conduit or mc (metal clad) which will be stranded. As far as coach wiring, everything should be stranded.
Interesting point about the 240V coach...I was intending on adding an inverter generator (6kW) 120/240 and use it as a back-up for my home.
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I completely agree with Sean here. That does not mean that you will find this to be the case. Most RVs that I have been into are run with NM and push-in receptacles. It is very fortunate for me, because this is a lot of the reason I get called. Then, I release the conductor, and put it under the screw, test the circuit and collect some money.
Standed NM is tough to come by (not available at Low Despot). For most boat work, I buy from <genuinedealz.com>. They are an effective supplier, but not always the best price. (Waste Marine can be counted on for worst.)
Be Aware that connections of stranded wire to receptacles, breakers and such often will require using a staked on terminal. The cheapo parts simply cannot accommodate fine stranded wire.
Matt - back to packing
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: Electrical Questions [message #201537 is a reply to message #201530] |
Wed, 13 March 2013 09:26 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| SeanKidd wrote on Wed, 13 March 2013 10:12 |
Mac, you are absolutely correct with your 50A service, however I need to point out that if you use a 2pole breaker to feed this service your potential is 240V phase to phase, to mimic the onan output, you will need 2 30A breakers on the same phase. (skip a space between circuits.
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Sean,
You are correct, but there is no reason to mimic the Onan. In actual fact, the coach wiring (if GMC original) is 240V - 3wire just as you describe. I have done mine this way to save the loss on the neutral. (Soon to have both an inside and an outside 50s.)
Matt - back to cleaning and packing
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: Electrical Questions [message #201546 is a reply to message #201530] |
Wed, 13 March 2013 10:00 |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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Senior Member |
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| SeanKidd wrote on Wed, 13 March 2013 10:12 |
Mac, you are absolutely correct with your 50A service, however I need to point out that if you use a 2pole breaker to feed this service your potential is 240V phase to phase, to mimic the onan output, you will need 2 30A breakers on the same phase. (skip a space between circuits.
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I'd like to revise this statement, the Integral handle of the 2pole circuit breaker is the best means of ensuring all power is removed from coach in the event of a fault. do not add 2 individual circuits on 50A shore power installation.
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
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| Re: [GMCnet] Electrical Questions [message #201570 is a reply to message #201526] |
Wed, 13 March 2013 13:23 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| k2gkk wrote on Wed, 13 March 2013 08:59 |
My 76 ex Palm Beach has the 6 kW Onan. Its output
is ~120 VAC. However, the single output is wired
to both L1 and L2 of the 240V (center tap neutral)
50A style 4-wire power receptacle. The matching
4-wire power plug goes to a double pole circuit
breaker. This allows running the two A/C units
on separate circuits (L1 and L2). I'm reasonably
certain that is the manner in which MOST of
the coaches using the 6 kW Onan are wired.
This is NOT in agreement with the advice below!
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You are partially correct. Early GM upfitted coached are wired for 240 volt 50 amp service. Later GM upfitted coaches and most non-GM upfitted coaches were wired with 120 V 30 amp service. This has nothing to do with the size of Onan installed.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Electrical Questions [message #201572 is a reply to message #201514] |
Wed, 13 March 2013 13:29 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| k2gkk wrote on Wed, 13 March 2013 08:36 |
IIRC, I would suspect that wiring in RVs should probably
follow the standards for boats. Both applicatilons involve
objects in motion with vibration and twist of the wiring!
Repeated flexing will eventually cause failure in solid
conductors.
Ergo, use stranded!
Boat wiring is also supposed to be with "tinned" conductors
to reduce corrosion of conductors which can add resistance
and the resultant voltage drop and possibilities of fire
caused by high resistance connections.
Fire is definitely a bad thing in either boats OR RVs!
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We are discussing non-vibration house wiring here. He is installing a receiptical on his house or garage to plug his GMC in to. He is reusing an existing 240 volt circuit formerly used for an electric dryer.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Electrical Questions [message #201573 is a reply to message #201552] |
Wed, 13 March 2013 13:35 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| A Hamilto wrote on Wed, 13 March 2013 11:03 |
I got the answers I needed. Thanks all.
To clear things up a little, I am running a new 25' wire from an existing 30A breaker in the panel (that used to be for the dryer) for a new shore power outlet to plug the GMC into. The old wire run to the dryer was less than three feet, and has been removed. No conduit in use or anticipated.
If the local Home Depot has a 25' roll of 8/3 solid w/ground, I will buy it (just because I am anal about voltage drop). Otherwise, a 25' roll of 10/3 solid with ground will come home with me.
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It sounds like you have figured out what you want to do.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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