[TSoul]

You have gotten good information. However, I would like to clarify something about a 50amp service. 50amps service is actually two 120vac lines. What this means is that you can draw 50 amps on both lines and it will give you a total of 100 amps at 120vac. So instead of having an extra 20 amps from a 30amp plug in you actually get 70 amps more. This is very helpful when one has two ac units or wishes to use multiple electric heaters. Just don't plug those electric heaters into on 15amp or 20amp circuit in the trailer or you will trip the breaker.
I hope this makes sense I wanted to clear things up a little and I hope I did not add to your confusion. Happy Camping.

PS you will love Martinsburg RV they are a great bunch of people.