[rohrmann]

That is exactly correct. Both hot legs are rated 50 amps, so together you have 100 amps. With the 30 amp system, you only have one 30 amp hot leg, and if you have a 50 amp system, which is two hot legs, connected with a 30 to 50 amp adapter, the single 30 amp leg is split to energize both the hot legs of the 50 amp panel. You are able to use any combination of loads with the 30 amps available, but can’t exceed 30 amps between the two hot legs in the 50 amp rig. On a house that has, say a 100 amp panel, you have two 100 amp legs, and this also applies to larger panels on a house, that you usually get two hotlegs of whatever the panel is rated at.