Again, I'll preface this with my limited knowledge of electricity...lol. The tranfer is wired in to the entire house before it goes into the breaker panel. so the entire house is "hot". It will trip itself out if the load is too big and you have to kill some breakers and then reset the generator. Turning on more and more breakers. The way my guy explained it to me is odds are all the stuff won't start at once (like both ACs kicking on the exact sane time so the load is typically not enough to trip the generator.