Originally Posted by JohnWedell
This is the best and cheapest way.
Before going this route, verify the campground will allow you to do it this way. Some mandate all connections be rain tight.
I know that our seasonal campground, from time to time, will have ponding water from torrential rains. Having a non rain tight 30 or 50 amp power connection is asking for, at best, having to go out and reset the breaker on the pole numerous times until you find a way to keep water out of the receptacle where the two cords connect.
My method, while not the cheapest, addresses the issue of water tight.