Originally Posted by raspivey
That's true if you try to wire a 30A RV plug like a 240V dryer outlet. A 50A RV will have two 120V hot wires and the converter will be split between them so it won't see 240V. You'll need a double pole 50A to do it and get full power.
50 amp 120/240 volt split phase service is one of the most confused and often misunderstood things we encounter on the forums. It's more accurately explained in the links provided in my post #2 above.
A 50 amp service going to the RV consists of TWO 120 volt legs (each at 50 amps), a ground wire, and most importantly a shared neutral wire. It's partly due to this common neutral shared, that makes the doublepole breaker trip if one line see more than 50 amps, so as to not burn up the neutral. This is due in part to load balancing, and is again explained in the links of post #2.
Unless the two 120 volts lines are wired to an appliance, then they stay separate and thus 120 volts.
At the electrical distribution panel inside the RV, it will have TWO sides to accommodate the two hot legs, and thus also keep everything it feeds from that point forward as 120 volts.
You may have say the first air conditioner, the electric outlets, and the water heater being provided power by the L1 side.
Then the L2 side may provide power to the second air conditioner, microwave, and the converter.
The converter (which converts 120 volt AC to 12 volt DC to provide power to the DC stuff), will NOT be split in any way. It will receive 120 volt AC from only ONE side (either the L1 or the L2) and not split between anything.
These pics below may help get a clearer handle on it that show the 120/240 volt split phase outlet (feed) and then the electrical distribution panel inside a 50 amp RV: