Originally Posted by rick danger
I think an ammeter will only check what something is drawing.
That's correct and even then you would be in line with the circuit which I wouldn't recommend. I use a clamp on amp meter for anything more then circuit boards. As others have said check the breaker panel, each breaker will have it's max current written on it.
My garage plug is only 15 amps and it will handle everything in my trailer except the AC. Running the electric hot water heater and the microwave at the same time would be pushing it but your lights, TV, radio and charger should be no problem.
I leave mine pluged in all the time.