I don't know what you are trying to do here? The AC is hard wired into the breaker box at the converter. You do not want to mess with this connection. If you try using a generator and shore power at the same time you will most likely be buying and new generator if you are lucky or if you are not lucky you could melt your Casita. The generator should run the AC without any problems. However If you attempt to run other 120V devices like the microwave, hair dryer, hot water heater, or maybe the refrigerator together you will have some problems. Turn off the air conditioner when using other devices. The DC devices, lights and fans will continue to work as usual as they run off of the battery.
If you need to plug your Casita into a 20 amp plug there are adapters that will do this. Any RV store like Camping World and even Wall Mart should have them. However I have not been in a wall mart that often. You plug in the cord from the Casita into the adapter and then plug the adapter into the wall plug at the generator. I would also suggest to get a 50 amp to 30 amp adapter also. You may find yourself in a place where they only have a 50 amp connection. We have used it 3 times since 2006. They look like this and there are many to chose from. 20 to 30 and 50 to 30 You plug your Casita cord into the adapter and the adapter into the wall or generator.
I was under no circumstances thinking of "trying to use a generator and shore power at the same time". What I was thinking of was making a second
shore power connection that led straight to the rooftop A/C and did not
connect to anything else in the trailer
. The point would be that if you had limited generator power, you could then connect the generator straight to the A/C and nothing else
. If it was an independent circuit, then a marginal generator might be able to power just
the A/C, if it wasn't trying do to anything else at the same time.
If you put a matching pair of 20 amp plugs say, on the roof, then you could temporarily unplug the A/C from the Casita's built-in power completely. As far as the trailer was concerned the A/C would be turned off (in fact, totally disconnected). If you ran an extension cord up to the roof and plugged a generator in, the generator would be powering just
the A/C. The generator wouldn't even "know" the rest of the trailer existed. I suppose there might be some issue with grounding the circuit or something, but it doesn't seem
like that should interfere with the trailer's power system.
If you again wanted to use the factory shore power connection for the A/C, then you could just plug the A/C back into the trailer. But you would then be powering not just the A/C, you'd also be recharging the battery, running fans and lights, etc. All which takes a little
more power than just running the A/C would.
Couldn't you just leave everything else turned Off? Yes, sort of. There are, I believe, a couple of electrical things in a Casita that don't have an "Off" switch (the battery charger for example). And using the factory shore power connection means that you can't
use anything else without adding the load to the generator. If the A/C was on a completely different circuit, the Casita wouldn't even "know" there was a generator running. So you could also run as many lights, fans and whatever as you had battery power for.
At least, I think
it would work that way. Any electricians out there who know better than I do, please feel free to correct me.