Originally Posted by SeaDog
A separate circuit wired to your dryer and or third AC should work fine.
I'd hate to do this, not knowing if the OP possibly has a 240 volt clothes dryer, which some RV's do. A separate 30 amp would not provide 240 volts to the clothes dryer, if that is indeed what he has, and only a 50 could do this.
To the OP, it is going to depend on how the campground pedestals are wired, as to if you can get 130 amps. I know you are asking about 80 amps, but actually you are asking about 130 amps. (100+30)
I know you may be wondering how, but you need to actually understand what exactly a 120/240 volt split phase 50 amp service is to begin with.
The 50 amp service is actually TWO (yes two) 120 volt 50 amp legs...so you have 100 amps total....and why you have a double pole breaker, which is in reality two 50 amp breakers tied together so if one side gets more than 50 amps, then both sides trip...which helps protect the common neutral shared between them.
As long as the outlets are correctly run off the bus bar in the pedestal, you should be OK...and I say 'should'. If the campground for some reason slaved the 30 amp outlet directly from one of the legs going to the 50 amp outlet..then you are going to have problems, but should be able to tell this from the circuit breakers and if each outlet has a separate breaker for each one.
Are we more confused than ever?
Here is a link which explains it better, and what is called load balancing:
Electrical Tutorial - Chapter 3 - 30 Amp versus 50 Amp
and here are some pics to help:
and then when you get inside your RV, you can either get 120 volts if you keep L1 and L2 as separate circuits to your appliances....or you could get 240 volts if your clothes dryer possibly draws from both L1 and L2.