Bob,
Take a single 208V load (say a baseboard heater with no neutral connection), it is fed with a blue wire from phase A and a black wire from phase B. Are you telling me that the "incoming" current in the blue wire is 120° out of phase with the "outgoing" current in the black wire?
I beg to differ about connecting both "-" terminals of two transformers together to create a 3 wire circuit(I wish I was good at posting drawings).
A 3 wire single phase circuit is really two single 2 wire circuits connected together. One circuit is connected across transformer windings X1 and X2, the other circuit is X3 and X4. The ANSI convention for a 3 wire single phase transformer connection is to tie X2 and X3 together to create a neutral point. Also it is common in the industry to say the "line to line voltage from X1 to X4 is equal to the voltage from X1 to X2 PLUS the voltage from X3 to X4".
