Your missing it. I will try to explain, again. A single 30 to 50A, 120vac adapter feeds just one leg of 120Vac on a black wire to an older design 50A connect. Originally designed as just a heavier lead over the 30A leads. White is neutral and green is fault return or ground. The dock side 120Vac-30A outlet will try to provide service to a cable and boat service that uses up to 50A of current. Still a single 120Vac lead of two this boat requires. 120/240Vac-50A provides an extra red wire. In normal application, this red wire can cover the total swing of the single phase of 240Vac ( between the red and black wires) or carry two leads of 120Vac @ 50A per leg between the black-white & red-white. 50A on the black wire, 50A on the red wire. The normal breaker for 120/240-50A service is a double pole breaker. 50A for each leg. So, in the required adapter and intended installation; red and black are tied together at the adapter, feeding two 120Vac-50A legs of services but still drawing from a 120Vac, 30A outlet and single breaker. Single pole 30A breakers can only take so much abuse. When they fail, it is not always in an open condition. Then wires over amp,, somewhere. Please re-read post 46 & 51. I'm not sure of the electricity on your side of the world. I assume all is 240Vac. Just imagine a white wire drawing from the middle of your 240V and resulting in two, 120V legs.