2nd AC Wiring

Look at this thread from July 20011. I think this will do what you want

One solution, and the one I like and chose for my installation, was to add another 20 AMP circuit to feed the 2nd HVAC with a power cord that plugs into the RV park power source. You plug your existing 30 amp cord into the 50 amp park service with a 50 to 30 dogbone, and then plug your 20 amp into the 20 amp receptacle. Much easier, and cheaper, than rewiring your trailer to have a 50 amp supply and you have your 2nd HVAC whenever you want it.

Dog Trainer,

The answer is a definite "some times".

The risk of running two units on 30 amps is low voltage. My comfort zone is 107 and above. Below that threshold, I either lower the load, or use other strategies.

It behooves you to monitor voltage when running 2 a.c. units on 30 amps.

There is more than one possible solution.

You could add an autoformer to support the voltage. This is my preferred solution.

You may be able to use a hybrid inverter/charger with load support. You may have to "force" the inverter/charger from load support to voltage support. They are not designed to support voltage, but rather to take care of short time over loads--such as running a microwave to heat up a cup of coffee.

Start-up is 3,500 watts each. Running is 1,500 watts each. Your converter is probably 8 amps. So, 1500/120 = 12.5 amps. 12.5 x 2 = 25 + 8 = 33 amps. Unplug your converter and it'll work. Otherwise, you may burn up one of those AC units. And, you still could, if, on start-up, you draw too much power (likely).

DogTrainer wrote:
Can you run just one unit on 30 amp and when connected t 50 amp both AC units run.

Yes. But you have to find the correct colored power wire ! In homes, usually on leg of 240VAC is black and the other is red (although sometime white). Who knows what colors they used in your trailer.

No one can give you an answer for 30A as there are to many variables. If you do a energy audit and have your usage the answers will improve. But the condition of your electrical and the pedestal including worn plugs and low voltage are factors. Temperature is another variable as covering your windows, awnings down, etc to help out. Plus your outher usage.

Experience some 30A sites when it's hot a few times and likely you'll be thnking 50A next time.

It is not likely to run 2 ACs on 30A, especially during extreme temps, when the load is highest. With cooler temp, no other electric draw, such as charge portion of converter working hard, having one AC running, the second one starting, while first is not still working hard to catch up, both may operate OK.

Jerry

Letme clarify my question.

If we pull into a RV Spot while traveling and it is 30 amp only will both units run, will i have to have 50amp service to run both units?

I dont want to paint myself into a only 50amp usage.

30A is 3,600W, 50A is 12,000W hence unlikely to have any problems.

2 smaller units will be OK on 30A with very limited additional loads. Provided of course you have good voltage which tends to be a summer time issue as does pedestal maintenance.

Only once did I have low voltage issues on 50A - older, full CG, hot summer day everyone running their A/Cs.