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 > How to run two AC's with 30 Amp Service UPDATE UPDATE

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chaffeekid

Chaffee, Mo, USA

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Posted: 06/02/10 08:17am Link  |  Print  |  Notify Moderator

Some background. I have a Coachmen 2001, 340 MBS Triton V10, Onan 5500watt genset, two AC units on the roof, unducted and only one at a time may run from the normal 30 Amp service. (Both will run when on the Generator.)
Ok so we just got back from a trip to Florida, it was great but unusally hot for the middle of May. When you run the air conditioner on high, which is needed to keep the coach cool the volume of the TV and anyone else talking is at an uncomfortable level!!
I have researched several threads on the fourm about modifying the electrical system to allow both airs to run. Well, after looking at them they were perfectly plain to me, but I have been trained in electronics.
BEFORE YOU START THIS MODIFICATION UNPLUG FROM SHORE POWER AND GENERATOR IS OFF!!!
What I thought is needed is a simplified version with lots of pictures so here goes.
[image]
These are the parts I purchased at my local ACE Hardware for a cost of 13.57. What you don't see is an additional male plug yellow, that you will see later in the post. Also you will need a handful of wire nuts, large (red) and medium (yellow). You will also need about 3 feet of 12 gauge romex 2 plus 1, that is a Black wire, White wire and a bare ground wire.
[image]
You begin the modification by locating the service box where the generator circuits feed the circuits to your coach.
In this box as is stated in another post that I followed are two black wires (10 gauge read large heavy), and two white wires and a green wire. You should also see two romex wires leaving the box to sevice the coach when you are using the generator.
[image]
In this picture you see my finger and thumb on the circuit (2 wires plus ground) that services my FRONT air conditioner. You will have to determine which air conditioner front or rear is on a seperate circuit.
If you examine the wires coming from the generator and the two circuits that they go to, one circuit will be fed by 10 gauge wires and the other by 12 gauge wire. My thinking was the single air conditioner would be ran by the lighter (12 gauge) wire, and I was correct.
Another way to check is seperate the two wires that you think are the circuit that powers one of the air conditioners. Remove the wire nuts seperate the black wire and the white wire of the circuit. Replace the wire nuts on EACH wire. Ok, now fire up the generator and see which of the air conditioners do not work. In my case it was the FRONT air. Not to worry, both airs will work when you finish the modification, you have just identified which one runs on its own circuit. Ok now before you touch anything else, TURN OFF THE GENERATOR, and make sure the unit is still unplugged from shore power.
[image]

My hand is holding the circuit that goes to my front air conditioner. Note that I have connected a piece of romex about 18 inches long via the two yellow wire nuts. The ground wire from this romex is connected to the green wire coming from the generator and the rest of the common grounds. You will need a Large wire nut for this ground connector. Note that I have mounted the additional service box, two common screws into the plywood that makes up the back of the storage box. CAUTION make sure that there is nothing behind the storage box for you to puncture. I used 1 inch drywall screws to mount the box (2). Also refer back to the first picture and those 3 little items to the left are strain reliefs. Install these where you route your wires through the service boxes. They will keep the sharp edges from nicking your wires and also prevent the wires from pulling loose from their circuits.
Note also in this picture the two large red wire nuts directly below my hand. These are the two to which the FRONT air was originally connected. You will connect a short piece of romex maybe 12 inches. Again connect black to black and white to white, and don't forget the Green to the ground circuit. Connect the other end of this romex to the new female plug (20 amp) in your new service box. Black wire to Brass colored screw, white wire to silver colored screw and bare wire to green for ground. You will have to strip and shorten this romex to allow it to fit into your new service box.
[image]
Ok, just about done. Shorten your pigtail so you have enough to plug it into your new box with no strain on it, I left mine about 8 inches long from where it exits the bottom of the new service box. Again make sure and install your last strain relief at the bottom of the box.
Now wire your MALE plug onto the pigtail, make sure and take the cover apart and slip the cap on first then strip the romex and again install the black to brass colored screw, white to silver screw and bare to green screw. Make sure that when you install these wires that you haven't stripped them back to far. If you do, you could cause a short if the wire is jammed into the connector.
Slide the cover over the connections and tighten all screws. Make sure and tighten the strain relief at the rear of the cap to keep the wires from being pulled out in case your hairy armed brother in law starts pulling on it!!!
Now carefully place all the wires back into the service box and replace the cover. Then replace the cover over your new service box. It should look something like this when you are done.
[image]
Buttoned up and note the extension cord plugged into our pigtail. Now both Air conditioners are working, one from the 30 Amp plug along with the rest of the coach, and the front one from our new circuit plugged into our new circuit.
When its plugged in to our box, it is now ready to be powered by the generator as normal.
Ok one last picture.
[image]
Ok this little red pen is what I consider a very necessary item. You can get one at your local hardware store, it will alert you to any circuit (AC) that is under power, read ENERGIZED. Make sure any circuit you are working on is OFF prior to service.
I know some are going to give me grief as I didn't install a breaker for the circuit. Most all of the posts I have plugged into are protected by a circuit breaker, as is the Air conditioner in the RV so I didn't want to duplicate it, and it would only apply to our short pieces of wire that we have added. At least that's my noodle on it.
Hope this helps someone and keeps you cool on those hot days!!
I am going to make one other mod to this, I am going to add another box with an outlet on it and a piece of romex going down under the coach to a plug so I can plug the extension in without having to leave my storage door open. I'll post pictures of this mod to my mod when I finish.

-----------------------UPDATE---UPDATE---UPDATE-----------------------

Ok, guys, here's the update to my project and the modification of the romex plug, which I to had a problem. First thanks for all your feedback, and here's the finish of the project.
I installed another electrical box next to the one I did above, it looks like this.
[image]
Note that I have also labeled the boxes for any new owner that I when I decide to sell the unit. I will also put an explanation letter with the manuals for the motorhome. Also note that I have changed the romex plug to a heavy duty plug that I had removed from some other piece of equipment, it is equipped with 14 gauge wire which will carry the load with ease, only 10 inches long. In fact you can see this cord in the first shot of the install above.

Next is the Marinco plug, it is listed as a battery charger inlet from West Marine.
Marinco Plug
It requires a 1 and 7/8 inch hole to install. I used a 2" hole saw that I had on hand and it was perfect. Before I cut the hole in the side of the Motor Home, I used a scrap piece of lumber, (plywood) and tested the 2" hole, works great. The plug installed looks like this.
[image]
Uncovered and ready for use like this;
[image]
The cap snaps into the plug and makes it water proof, ok, water resistant? That's why I bought it from a Boating supply house!
Wiring the plug is easy it has color coded holes in the back, don't forget to slip on the rubber boot then insert the wires and tighten the screws.
Lets see the back of the installation.
[image]
Note that where the wire enters from the storage unit above, I used a 3/4 inch hole saw and placed RV putty around the wire, top and bottom stuffing it up into the hole. Prevent the creepies and crawlies from coming up the wire.
I used a 2 1/2 inch hole saw to make a relief hole around the plug, I am going to seal the area with fiberglass resin after these pictures were taken to prevent water intrusion into the foam and wood etc.
My unit has 1 inch of foam sandwitched between the outside fiberglass, then luan plywood, 1/8" ? then the foam, then another 1/8 luan, then the plastic covering, careful of that, it will grab your hole saw so cut the relief hole in it with sissors.
Here's a close up
[image]
Note the drip loop in the wire. This is in an open bay under the storage unit, so it will be wet when driving in the rain. I also installed the retaining clips with stainless steel screws.
And yes, I could have used a double gang electrical box, but I liked the two seperate units
To use the front AC unit simply plug an extension into the Marinco plug, move the yellow plug to the Aux plug location and you can then use both air conditioners at the same time! To use the AC's on the Generator, or restore normal operation, just move the yellow plug to the Generator box.
Well that's it guys, hope you like it.
Happy Trails
Jim


* This post was edited 06/13/10 03:23pm by chaffeekid *



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crickeydog

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Posted: 06/02/10 08:45am Link  |  Print  |  Notify Moderator

Interesting. However, I'd have used the need for additional power to convince the DW it's time buy a new MH with 50 amp service. There's only several thousand of'em sitting on dealer's lot's all over the country right now. JMHO.

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Posted: 06/02/10 10:22am Link  |  Print  |  Notify Moderator

Very well written and easy to follow. Of course, I too, have spent way too much time around electricity. I would suggest, as your next mod, would be to replace that double gang box that the ocean air has eaten away...[emoticon][emoticon][emoticon]... but that's just me......Dennis


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427435

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Posted: 06/02/10 10:53am Link  |  Print  |  Notify Moderator

Our Itasca only has a 30 amp supply but will run both air conditioners. However, it also has a built-in energy management system that will kick one A/C out if necessary and then restart it when other loads drop off.


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Posted: 06/02/10 10:58am Link  |  Print  |  Notify Moderator

My '96 Pace Arrow would run both ACs on 30 amp. The Intellitec controller did all of the cutting out when needed. The rear air was 10,500 and the front 13,500 so that helped out a little on power draw also.


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VintageRacer

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Posted: 06/02/10 11:56am Link  |  Print  |  Notify Moderator

Against code to terminate Romex with a temporary plug, I do believe...


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chaffeekid

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Posted: 06/02/10 01:28pm Link  |  Print  |  Notify Moderator

Thanks for the comments guys, yes, I to have had a coach with the automatic change over. It was a 2002 Pace Arrow, great coach. Unfortunaly, this one isn't equipped as than one was.
Dennis, that box is in great shape, no rust really, just case hardned kinda like my 357 Mag [emoticon]
Thanks again guys, by the by, ordered my Marinco 15A battery charger inlet from WestMarine, www.westmarine.com that I will be installing, down below the storage bay door, then I can plug the extension cord in when needed and the storage bay can remain closed.
Here is a link so you can take a look.
15A Battery Charger Inlet
Happy Trails
Jim


Joatha

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Posted: 06/02/10 01:33pm Link  |  Print  |  Notify Moderator

Oddly enough, I'm about to do the same project on my 1990 Winnebago prior to heading to Florida in a couple weeks. I had already scoped it all out and was going to do it pretty much the same way. It should be an easy project.

I do have to point out, however, that you shouldn't use the Romex for your plugin wire. Romex is to be used for permanent installations - not as part of a cord that gets plugged and unplugged. You need to get some wire that is multi-stranded and designed for such use. If nothing else, get a piece of extension cord (one that is rated appropriately) and cut the ends off and rewire. It should work just fine then.

* This post was edited 06/02/10 01:39pm by Joatha *


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hershey

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Posted: 06/02/10 07:09pm Link  |  Print  |  Notify Moderator

My 30 amp MH also has the energy management system and it works well, but it has to deal with the draw from two AC's, one water heater, one microwave and one washer dryer.
In my system the AC's are the only thing that isn't operational with the inverter. So I split my incoming wire to the inverter/converter and put a male/female plugs in line. When I'm using the two AC's (off the 30 amp shorepower) the rest of my MH is run off the 20 amp circuit from the shorepower. WHen running off the Generator, I just replug the inverter/converter back into whats normal.


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chaffeekid

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Posted: 06/13/10 08:33pm Link  |  Print  |  Notify Moderator

Ok guys, I've updated the post with a couple of other mods, check it out
Happy Trails
Jim


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