15/30/50 SHORE POWER PLUG IN ?

In Missouri at a Campground we sat up and connected 50 amp to ems. Went in and turned on the lights ACs were already on. Immediately notice the lights wer real dim with one side dimmer than the others and the Acs not wanting to run immediately hit the generator went to tower and disconnected. Figured everything was fried but was running fine on generator. Got hold of the handyman and he called boss. The ems plug in was hot. Told him what happened and he insisted everything on his end was fine at first. We moved to a different site and everything was fine. he gave me every kind of story you can think of what was wrong. never did find out but I figured one hot lead must have wired to the other. Others have said the 50 amp is two 50 amp and a common ground. I cannot see how to add up to 120 volt 50 amps to get 240 volts.