I have been told that when a RV has 50 amp service, one branch feeds the 2nd (13,500) a/c only, and the other branch feeds the rest of the trailer including the main a/c unit. Is this true? What I want to do is use a 4 prong-3 prong adapter to plug the 50amp cable into my 3000 watt generator. I don't think the generator will reliably run the 15,000 main a/c hence I want to run only the small a/c. Will this work? Or will the trailer wiring not allow me to feed the bedroom a/c when plugged into a 3 prong 30 amp service?