First of all, Most, 99%, of the RV's are 120 volt, period, end of sentance! This is regardless of amperage, i.e. 20, 30, or 50 amp! 20, or 30 amp consists of a single hot 120 volt hot lead, a single neutralleg, and a ground leg. A so called 50 amp service consists of two 120 volt hot legs, each capable of handeling 50 amps, a common neutral leg, and a ground leg, 4 wires. This is identical to an electric dryer circuit, which draws 240 volts @ 50 amps. The differance with an RV is you do not use the 240 volts, you use two 50 amp 120 volt circuits.typically wired so one AC and the hot water heater and some 120 volt circuits wired to onE leg, the second AC, furnace, microwave, and the rest of the 120 circuits wired to the other. So while the pedestal is wired identicle, if you plug your dryer into it it is 240 volts, if you plug your RV into it, it is 120 volts!! Unless you are inanindustrial area, you have 240 volt service, in an industrial area you could have 3 phase 208 volts, which is a differant ball game.