Just got back on here .... Glad I came out ok as I was just copying what DMBRUSS.com listed. He is the author of the top drawing as well... I would have measured my 50A MALE to 30A FEMALE adapter but it isn't at this location... I feel it is correct as shown but wish I could have measured one to be sure...
It does make sense to me to only grab one of the HOT legs when coming down from 50A to 30A service. Shorting those two HOT LEGS together on the 50A side would surely cause a very LARGE SPARK haha... Thats 240VAC between those two HOTs...
Roy Ken
