Question on adding a 2nd A.C. To a 30amp motorhome

I know this topic has been discussed here before (2015 according tot he library) but I just needed a point of clarification. If I have a motorhome with a 30amp service and wish to add a second A.C. To be used solely while at the campground, would I just purchase a 50amp "Y" adapter that would have 30amp & 20amp plug and, using the 50amp hook up from the campground pedestal, plug the 30amp service into the one leg and the second A.C into the other 20amp leg and that would work without a problem?

I think that you would have to make an adapter there are 20+30 to get 50 but I haven't seen one tht goes the other way.

So no adapters with a 50amp male and a 20 & 30 (or two 30)amp females?

I found a Conntek RV Y Adatper Cord with 50 Amp Male Plug To (2) 30 Amp RV Female Connector (3-Feet) on Amazon.....$99 which is YIKES but it is available

My main question here is can I use the 50amp connection from the campground pedestal, and using a "Y" adapter split that and use one leg to power the motorhome 30amp service and the other to power what would essentially be a heavy duty extension cord to the second A.C. ?

Yes, 120 volts is 120 volts.  But just like the RV has a 30 amp breaker on the main power inlet, you must install a 20 amp circuit breaker on the air conditioner power, otherwise you'll only have the park's 50 amp breaker protecting the A/C, creating a fire hazard.

This is still technically a code violation as is using an adapter to plug an RV's 30 amp power cord into a 50 amp outlet. The current limiting breakers are supposed to be at the source, but having them at the RV's power inlet is better than letting the full 50 amps go through wiring designed to handle much less current.

I understand Lou....we just came back from Ocean City MD and Washington DC and the daily temps were near 90 degrees and our site was in the sun. The lone 15,000BTU A.C could only get the coach down to about 80 degrees. At night we faired a little better, but during the day it was a killer, even with windows covered. I was just looking for an option as next year we are heading out to Yellowstone and may encounter some of the same.

I'd upgrade it to 50 amps by adding a new panel and feeding the old panel from the new one using a 30 amp single pole breaker. That would make the old panel a "sub panel". Then I'd use the other leg to feed the new A/C with a 20 amp single pole in the new panel. You'll have to upgrade your cord to a 50 and I'd feed the new panel with a 50 amp double pole breaker installed in it as a "main". You'd only need a new 4 space panel to do it. Two spaces for the 50 and one for the 20 and the 30. I'd also un-bond and the old panel and un-bond the new one.

PS: I might also add a outlet for a electric heater to the 20 amp circuit so I could use it to plug in a heater somewhere when it's cold since the 2nd A/C unit would be turned off when the heater was on.

Then I'd carry a adapter so if I camped somewhere that only had 30, I could still plug in. Just not use both A/C's.

LABEL THE OLD PANEL "SUB PANEL" SO SOMEONE DOESN'T THINK THE MAIN IN THE SUB SHUTS OFF THE WHOLE RV!!!

It would cost you around 300 bucks or so.

Something like this: http://www.homedepot.com/p/Square-D-Homeline-125-Amp-4-Space-8-Circuit-Outdoor-Main-Lug-Load-Center-with-Ground-Bar-HOM48L125GRB/100196368

OR (Not as good)

Just run a 10 gauge regular extension cord from the campgrounds 20 amp outlet to the new A/C and hope it's not fed off the same leg as the 30 is.

NOTE: The way you have planned would work but you have a 30 amp cord and a 20 amp cord (if not 15) plugged into a 50 amp outlet. People do it all the time by plugging a 30 amp RV into a 50 amp plug using a adapter but upgrading the way I told you first is a better option.

How I would do it if it were MY 30 amp RV (Instead of the 50  I have)

I am aware that there is indeed an adapter with a 50 amp plug and either two 30 amp or a 30 and 15 or 15/20 amp outlet

It appears you have that adapter

And I'd then run 12ga wire to either a storage bay or to an inlet on the side of the  Unit, and 12 ga extension cord from there to said adapter.

IF I am reading the original post correctly that is EXACTLY what you are planning on doing

NOTE: On 30 amp sites with my 50.. I do the same, I break out one A/C and run it 9independent on the 20 amp outlet.

just remember no mater what you do the line leading from the 30 connector on the Rv  to the fuse panel is only sized to carry 30 amps. So even is you change the breakers you can only still carry 30 amps to the panel 2 ac will max out your 30 amp capacity on your wire to the panel

Just wire your 2nd ac to a dedicated cord and plug it into the 20 amp outlet found on nearly every campground electrical post.

x's 2
I was just going to say the same thing

jack l

jubileee said:

Just wire your 2nd ac to a dedicated cord and plug it into the 20 amp outlet found on nearly every campground electrical post.

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X2... Our previous 30 amp coach had two A/C's, but only one at a time could be run on 30 amps via a selector switch. Both A/C's could be run though, when on the 7KW onboard generator. I split out the bedroom A/C's wiring at the generator junction box, and added a 20 amp plug and outlet setup that allowed the A/C to be connected to a 12GA extension cord that was plugged into the park 20 amp utility outlet, or connected at the new coach outlet so everything worked normally.

Just wire your 2nd ac to a dedicated cord and plug it into the 20 amp outlet found on nearly every campground electrical post.

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That's the simplest way, but we advised that a pedestal with 30A & 20A outlets (no 50A) is being served by only a 30A circuit, i.e. the 30A & 20A outlets are sharing one 30A source.  You are essentially limited to 30A total, though there may or may not be a breaker upstream to enforce that.  However, if the pedestal also has a 50A outlet, the feeder circuit is 50A/240v and there is plenty of power for both 30A and 20A outlets to function to their max capability.

Just want to finish this thread by saying I did add a second A.C.  I used an existing non power vent opening. I was able to run 12/2 wire with minimal exposure. I added a separate 20 amp circuit breaker panel in the outboard compartment that houses the existing shore cord and inlet for the generator. I installed a separate 20 amp inlet next to the new circuit breaker box and created an extension cord using 12/3 stranded wire, The A.C. I purchased was a Domedic Brisk Air 2 15.000 BTU non ducted with a heat strip. The only issue we had was the styrofoam shroud that covers the front part of the unit (under the exterior roof shroud) rubbed the hamster wheel on the roof mount and had to be sanded down quite a bit (in my opinion) in order to get the wheel to move freely. Total time invested for me with a friend was about 2 days (16hrs) and total costs about $850. This should bring great relief in very hot conditions (90+ degrees).