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Old 04-29-2012, 02:59 PM   #1
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2010 31' Classic
Quincy , Illinois
Join Date: Feb 2008
Posts: 22
Adding additional AC - How to Wire

I am having an additional AC unit added to my 2010 Classic (13,000 BTU, no heat pump). I have read other postings about wiring this additional unit via separate circuit which would allow us to use both units at once but would require two plugs.

I also could have the unit wired into the existing 30 amp service BUT realize I could only run one unit at a time with that set up.

I'm asking for advice from others on which way to go. I have been told by the people who will do this they can go either way. Also, I have given them Andy's advice I found on the site about drip pans; bracing, etc. They assure me they have done this before.

Thanks in advance.

31D Classic 2010
F350 Ford Diesel DRW 2012
27FB Safari 2008 (traded)
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Old 04-29-2012, 03:45 PM   #2
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1973 27' Overlander
Kenner , Louisiana
Join Date: Apr 2012
Posts: 14
The best way to do this is to redo the main power panel and your trailer will be wired for a 50 amp service. That way you can run both at the same time. Whats the purpose of adding air if you cant use them both at the same time? Do it right the first time and you will not regret it.
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Old 04-29-2012, 05:05 PM   #3
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1992 29' Excella
DFW , Texas
Join Date: Oct 2008
Posts: 23
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On our #2 AC install, I ran 10ga MC cable between the skins and down to a 110 male plug I installed in the Power Supply compartment. From there I'm able to use a 10ga Extension cord to separately plug in to 20amp 110 service. I also routed the condensation line down in the same fashion and it drops out beneath the trailer. It took drilling a couple of holes into the frame by the AC and it also took a lot of patience and an inspection camera to be able to intercept the pull tape and work around the internal structure (use a fiberglass pull tape if you go this route).

The permanent, male electrical 110 boxes are hard to find but they are available from an electrical supply house. HD, or Lowes didn't carry them.

Advantages to us are that we are able to use Texas State Park hookups designated for 30amp service.

The current disadvantage is that I'm dependent on an external breaker at the electrical hookup. The fix for that is that in the future I'll install a small breaker box with a single breaker for that purpose.

In whatever manner the electrical is routed, the condensation line needs also factor in.
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Old 04-29-2012, 05:19 PM   #4
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2011 34' Classic
Westchester Cty.NY , / Miami FL
Join Date: Jul 2007
Posts: 3,122
the 50A service does involve a much heavier power cable. you might want to try lifting one to make sure it isn't an issue.
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Old 04-29-2012, 05:51 PM   #5
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1981 31' Excella II
New Market , Alabama
Join Date: Sep 2011
Posts: 5,280
THere is no reason you can't go with a 30A 220V system that is powered off of a 50A service. You do need to make sure you have a 30A 220V main breaker to protect the system. I would run one pole to the 30A 120V to the existing wiring and then add a 20A 120V circuit off the other pole for the new AC unit. You would need #10-4 SO cable with the 50A male plug on it. I have the pigtail part of mine down already and plan on adding another 20A circuit so I can run extra space heaters when I am at home.

Right now I have a L14-30 male twist lock on the end of my pigtail. I am not using one pole right now but if I was then I could split out each phase to a different 120V source if I wanted to. Since nothing is running off of 220V in the trailer I can hook each phase to a 120V source. All that is necessary is to have 120V relative to ground on each pole. It won't matter if there is 220V between them or now since there is nothing in the trailer that is 220V. So you can have two or three pig tails to adapt to whatever source you have.

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Old 07-31-2012, 07:30 AM   #6
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1966 24' Tradewind
Winchester , Virginia
Join Date: Jan 2012
Posts: 3
Blog Entries: 1
10ga MC?

You mentioned in your post you used 10ga MC wire. I am assuming this is 10 gauge Monster wire. Is that the wire used in cars and audio systems? How does that work on an alternating current? How do you ground? I'm very familiar with romex but this looks to be quite a space saver.
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Old 08-01-2012, 05:46 AM   #7
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1973 27' Overlander
Kenner , Louisiana
Join Date: Apr 2012
Posts: 14
MC means metal clad., it is like romex but instead of plastic covering it is metal or aluminum spirals. Do not use monster cable for AC voltage unless it is rated for AC use.It will say it on the wire.
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Old 08-01-2012, 06:08 AM   #8
3 Rivet Member
2008 31' Classic
Lake Charles , Louisiana
Join Date: Apr 2009
Posts: 144
I cannot help you on the "how to" but will say you are going to love it after you have the second AC installed. Two AC's was top priority when we started shopping for our new AS in 2008. We have never regretted the extra cost or the long trip we had to make to get the trailer that had everything we were looking for. Being from the South, I wanted to always be able to cool the trailer down regardless of the outside temperature. Another big plus we have found is to operate the rear unit when we are in the front watching TV. That eliminates the volume going up everytime the front AC kicks on. Makes it a lot more quiet during conversations. Appears you are getting some really good advice here. I hope it works out well for you. You will not regret your decision plus it will add value should you ever choose to sell.........steve
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Old 08-01-2012, 07:18 AM   #9
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1991 34' Excella
1963 26' Overlander
Central , Mississippi
Join Date: Nov 2006
Posts: 5,002
Images: 29
Blog Entries: 49
For my second air, I installed a second (small) breaker box and used a second 20A power cable. Yes, I have to plug in 2 cables now but the upside is I can stay in a 30A site and plug the rear air into the 20A outlet. Only 1 time have I stayed at a campsite that did NOT have a 20A in the box along with the 30A (no 50A sites either)

I also have a 50A to dual 30A pigtail. If the camp does have 50 available, I will usually get pay the extra $2-$3 and stay in that site.

The install is posted in the 34' thread listed in my sig.

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A honkin' long 34' named AlumaTherapy
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