On Tue, 07 Dec 2010 21:06:47 -0700, Doug Winterburn
wrote:

OK, the two hots are 180 degrees out of phase with respect to the
center-tap/neutral/ground.

At any rate, if identical loads are present on each hot, there will be
no neutral current.

If the phase is 180 degres out of phase and you add them together you
have no potential!

Mark