shore power 110 or 220

Well, as someone who is electrically literate, I guess I'll have to pull out my meter next time I'm at a campground. I've always thought that a 50 Amp campground outlet is wired just like a home dryer outlet. The way 110/220 electricity works is that either hot side to neutral (which, although is tied to ground in the supply panel is NOT considered the same) yields 110 Volts while measuring across the two 'hot' terminals provides 220. The only difference is that with campers, the wiring does not allow for 220 Volt use, just two 110 volt circuit that divide the RV's load between the two 110 Volt feeds. If you look at the power lines into your house, you will see 2 'hot' leads, a neutral and a ground. The technical answer is that your hot leads are coming off each end of a center tapped transformer that provides 220 Volts across the two ends of the transformer wiring and either end to the center tap (which is neutral and also tied to ground) provides 110 Volts. To be properly wired, the outlet must have each hot terminal connected to opposite ends of the transformer wiring so to provide 220 across the two hot legs. Unless RV outlet posts have some odd circuit breaker mount, a 'twin' 220 Volt breaker will draw from the two different sides of the supply transformer.