I got a customer who wants a service to supply a motor home and his utility building. The utility building is 12x16. Right now there is no outlets or light in the utiltiy bldg. He also wants to have an outlet he can plug his motor home into. My thought is to mount a 100 amp service on the utilty bldg. with outlets with in use covers for his motor home. Install at least one light and one outlet in the utility bldg. with the outlet on a GFCI. Is there anything in code that limits the size of the bldg. that a service is to be mounted too? I myself cannot think of any now. The bldg. is permanent but of course the motor home is not. The motor home has a 120 volt cord on it. Anything wrong with my idea here. I've never had to install a service on a bulding this small, but I don't think there is any violations just so it is at least 100 amps.
Unless, the local jha has issue with it, I think you are good. Don't forget a second ground rod if no other grounding source is available. Also watch your overhead clearances if its going to be a service drop instead of a lateral
This was a common installation here when they were still making trailer parks. The user got a block house instead of just a power post so they had a place to store their stuff that they did not take home every summer and the power there served the RV. There may be a real bathroom in the block house too.
I checked with the AHJ here and they said it was alright, but to make sure the motor home outlet was just for charging the motor home and not for permanent dwelling. They said the meter could be pulled if it were a permanent dwelling. Don't know exactly how they would determine this, but the homeowner did say it was for temporary use.