This is good stuff Scott, better than crossword puzzles.
You didn't mention L-N in the parallel case. But it seems to me that there must exist a voltage with respect to the earth.
If you left the secondaries in series but eliminated the center tapped neutral what would the L-L voltages be? How about L-N (N being the utility's earth reference)?
What I expect is that L-L is 240 V and L-N is 208 V.
The explanation being that in this set up we are getting 240 V from two 208 V terminals 120 degrees apart instead of in the single phase case where we got 240 V from two 120 V terminals 180 degrees apart.
Am I close?
(If I am, then I definitely didn't understand something.)
