Wiring Diagram 240v No Neutral. Case 2 of the three phase supply has 3 wire delta connection. It may not be obvious to all but this is a very north america centric question.
One wire is the active wire and the other is the neutral wire. 240v gfci work with no neutral. And the second to the neutral wire.
If connecting up in a buckboost then one side of the 120v secondary would be connected to the earth ground.
Ring circuits from 32a mcbs in the cu supplying mains sockets. Both 3 wire and 4 wire spas must be gfci protected. Take two wires and connect your single phase cables to any of the two phases. Therell be primary lines which are represented by l1 l2 l3 and so on.