[asdf38]

Guys there are no problems here so long as the wiring is matched to the breaker for it. Even if the shore wiring is only rated for 20A it's protected by the 20A breaker. So it's safe no mater what your main breaker is. Just don't draw more than 20A unless you want to pop it.

And a 30A shore breaker with 30A wiring could also be plugged into a 20A main breaker without any problems. Just like in your house you have the 100 or 200A main breaker feeding a bunch of 15's and 20's...That's the point of breakers, to protect their branch from potentially higher current available on the bus.