A/c Mod

ed s · 07-21-2010, 04:29 PM

Greetings,
Looking for some ideas from you guys.
My rig has three a/c units and the one in the garage I need to run all the time when we are at dog shows this time of year. Most dog show sites do not have 50 amp so here is what I want to do. I want to splice into the power line to the garage a/c, run the power line to some sort of wall mounted switch box and feed the a/c from either the coach or directly from shore power thru a plug end installed outside the coach.
A box with a switch that I flip the switch one way and the a/s us powered by the coach, flip the switch the other way and it is powered by the exterior plug to shore power.

Any one have any ideas what kind of switch box I can use and where I may find one.

Thanks

Ed

ed s · 07-21-2010, 05:35 PM

ops,
I need ideas for a switch and for a switch box

Bob86ZZ4 · 07-21-2010, 07:38 PM

I'm not understanding (which is pretty normal for me). If you can run your generator it'll power everything so not a problem just turning on that garage a/c unit on generator power. Now, you can get an adapter to change your 50 plug on your shore power cable down to a 30 amp plug. Then get an adapter to reduce that 30 amp plug to a 15 amp standard wall plug type. Then you can plug into any old standard 15 or 20 amp wall plug and run whatever you want in the coach. Just can't turn too much stuff on. The single roof air will run just fine from a standard wall outlet like I've said. I've done it a bunch with my rig. I always have both of those adapters in my electrical compartment. As well as a couple of 25' 30 amp cords that I bought at Walmart. That way you can run rather heavy low resistance wire all the way to the nearest wall outlet on any house or building. Is that what you want to do? Be able to power that single roof air unit from a plug somewhere?

ed s · 07-21-2010, 07:51 PM

Bob,
I do not want to run my generator all the time when I do not have 50 amp power available. When it is hot I need to runn two generators because the on in the garage is for the dogs and I do not want to turn a fan towards the front of the coach and blow dog hair up there.

I want to be able to use the coach (50 amp, 30 amp shore power or generator) or a direct power line to the one a/c. Maybe I am not making this clear

Bob86ZZ4 · 07-21-2010, 10:24 PM

But couldn't you just not use the other a/c's and only use the one in the garage when you have your 50 amp line plugged into a regular 15 amp recepticle using the adapters? Wouldn't that be essentially the same as running a cord directly to that rear a/c unit from some recepticle on the side of the building?

ed s · 07-22-2010, 01:41 PM

Bob,
So many of the dog show sites have limited elect. Some 30 amp, some 20 amp and once in a while I find a 50 Amp.

Now my reasons for what I want to do is two fold.

First with 30 amp power I can run one ac and other stuff in the coach. That means the garage ac will run and the other two will not and I like the coach cool. I do not want to run a fan from the garage to move cooler air up front cause of dog hair.

So I want to be able to plug into 30 amp and run the front ac along with other stuff. I want to be able to plug the garage ac into its own power source when I am not running the gen or plugged into 50 amp.

I need to splice into the power line going to the garage ac, install a male plug to outside of the coach, have a box where the wires meet along with a switch to direct power for ac from either the coach or outside source. Then the garage ac will be a stand alone unit.

The 2nd reason is. Last week while in Duluth for four days there was only 20 amp power available, temp in the 80's, humid and I had to keep doogs cool. So I ran the gen. Well I had issues with the gen turning off by itself 4- 6 times during the day only. The other issue I had was I was not able to turn off the gen with any of the three switches to start and stop the gen. I came back to the coach several times to find that the gen had stopped running and temp in the garage was high 70's. Too hot for the dogs. With this change in the garage ac I can plug it into a 20 or 30 amp outlet then I can plug the coach into another. Now if I lose power in one of the outlets the coach is still being cooled by the front or garage ac. (better than non at all) Alos if we lose all power I can set the auto gen to kick in and keep some ac running.

Maybe this makes better sense.

Ed

Bob86ZZ4 · 07-22-2010, 02:02 PM

AAaaaaahhhhhhh,,, now I'm caught up. I wonder if it would be easier to get to the main circuit panel and find the breaker that powers that garage a/c unit. Then, you can take the wiring that runs from that breaker and install your wiring there. I'm pretty sure the roof airs are 120 volt. So, the breaker should be a single pole 20 amp I'm guessing (I'll check mine tonight). The hot wire coming from the breaker what about installing a single pole double throw switch here? Then by throwing the switch one way it will connect the hot wire to your circuit panel breaker. Center up the switch and nothing. Throw it the other way and it will connect the a/c hot wire to your new incoming hot wire. Hard wire a male weatherproof recepticle on the outside of the coach, or in a storage bay? Then you just run a heavy duty extension cord from a shore power recepticle to that new male plug. The only thing I'm not sure about is if you need to also isolate the grounds and neutrals. Might need to install another double throw single pole switch to do that? Or could you use a double pole double throw and use it for both the neutrals and hots? Wears RadD when we need him? I'm still liking my idea of doing it near the circuit panel rather than trying to tie in back near the a/c tho. Grainger has all kinds of heavy duty switches and stuff. Come on RanD, help me out here.

Bob86ZZ4 · 07-22-2010, 02:04 PM

Hay, you were at the Duluth dog show? My brother is a vet, he was there. He has a 30' bumper tow trailer with a garage in back that he does vet stuff in. I think he does semen draws or something. Did you see him there?

ed s · 07-22-2010, 02:05 PM

I saw his trailer but did not see him. I was parked on the other side of the building.

blizzardND · 07-22-2010, 09:08 PM

Do you come to West Fargo in the spring? I remember seeing a couple of T/C in the HS parking lot which is right next to my house. We seem to be too busy those weekends to see the dog show, but I like to check out the RV show in the lot!
-blizz

ed s · 07-23-2010, 07:53 AM

-blizz
No I have not been out to West Fargo as of yet. Mostly stay in WI,IL,MN,MI,and IA. Have gone to CO and east coast for our Nationals and will do other states for specalities but for a weekend dog show I try to stay within a 6-8 hour drive.

Bob E · 07-23-2010, 08:17 AM

Suggest you install a separate box between the main breaker box and your rear A/C unit. then equip that box with a "transfer switch" rated at 20amps. A transfer switch is basically a double pole, double throw switch.
You then feed one side of the transfer switch from the main breaker box, and connect the other side to your (separate) 30 amp shore power cord.
Then you can safely, switch your rear A/C between the main motorhome power, and (separate) 30amp shore power.
Make sure you run the proper ground wires when you do this, it keeps you from doing the 60 cycle dance.

Radman · 07-29-2010, 07:30 AM

My old truck had an Front/rear/both AC switch for just the situation you described. When parked with a 20amp service you didnt have enlugh power to run both AC units so you could lock one or the other out. I never tore into it to see how it worked but I assume it was just a few sets of HD contacts.

Rad

Ran D. St. Clair · 07-29-2010, 01:07 PM

Sorry guys, I just noticed the post. I don't think I am qualified to properly answer the question. I am more of an electronics engineer than an electrician. I don't know the codes, and I may not be able to forsee all the safety issues that could arrise, especially if the shore power you happen to be using is wired wrong. The double pole double throw switch idea sounds like the obvious solution but I am not able to recommend a specific switch or switch box from Granger. I also can't answer the issue of whether you need a 2nd double throw double pole switch (ganged with the first) to switch out the neutral wire. I would guess that would be the way to go but I know just enough to know that I don't know enough.

Thanks,

Ran D.

Ran D. St. Clair · 07-29-2010, 01:26 PM

Just had a thought...

Instead of using double pole double throw switches, wire the circuit with a couple of 3 prong plugs and a single 3 prong socket that one or the other plugs into. It's simple, cheap, and guaranteed to "break before make" meaning your generator will never have a chance to fight with shore power. It would also act like a double throw double pole switch for hot, neutral, and even ground. I can't think of any safety concerns, but like I said, I am not an electrician...

Ran D.

ed s · 07-29-2010, 04:45 PM

Thank you for your thoughts on this.
The more I think about it I am leaning to just male and female plugs on the current hot line and then run another hidden line from the ac to the outside of the rig to plug shore into. Then all I have to do is open the ac over and unplug and plug. Unless I find a better safe way this may have to be the solution.

Ed

Bob86ZZ4 · 07-29-2010, 08:44 PM

I like that idea too. Just need to make sure to use heavy duty cable/wire. And plugs. Maybe a good twist lock type of plug would be best? I bet you can find something at a very good hardware store. I'd try to wire it near your circuit breaker panel tho. I bet it'd be easier to find the line there that runs to that rear roof air. I don't like the idea of the cable coming down from the actual roof air unit.

rjdhomes · 07-31-2010, 01:13 PM

ed s, Try doing a search for " 50 Amp Rv Box Adapter " Camping World sells them- this may help you out at venues where you have standard ac power available, but no 50 amp.

Also, Renegade used to have the setup you are asking for as standard, with two outlets in the power cord storage compartment. Two power cords were plugged in while operating generator and unplugged and put into the shore power while at the Rv Park. If you are going near Bristol, Indiana, Renegade service could modify your coach easily, they are not very expensive.

Bob

ed s · 07-31-2010, 06:14 PM

Bob,
Thanks, I will check with my friends at Eldorado if they can do this for me or it may have to go back to Renegade anyways but not sure I want to wait that long to have it done.

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