Four pages of BS already. To the OP. If your electrician is not familiar with rv wiring just tell him to install a standard 4 prong 50 amp 240 volt electric range receptacle. You are good to go. SIMPLE! Yes you can use #8 wire depending on the distance to the outlet. There are sites on line that you can use to determine whether you need #6 or larger. Yes the breaker for the feed is a double 50 amp allowing 50 amps @120v on each leg for a total of 100 amps @120v available for the rv. If you have a 240v device such as a clothes dryer you would have 50 amps @240v available for it using a correctly wired receptacle for it in the rv.