To make it even clearer,nothing says you have to wire a 50 amp RV out with a 2 poll 50 amp breaker, you can easily use a 2/20, 2/30, 2/40 or even a 2/50 as long as the wire is sized correctly. I love it when someone corrects you and they didnt read what was wrote!! Furthermore, if his electrician has already run 3 #10 wires, simply adding a fourth wire would seem fairly easy. Maybe its run in Romex, I dont know, then he could replace the whole thing.
2/20 = 2 hot number 12 wires + neutral and ground
2/30 = 2 hot #10
2/40 = 2 hot #8 wires
2/50 = 2 hot #6 wires(some would say #8 here also)
all of these could easily be used with a 50 amp RV PLUG!
