nestork has brought this to us :
What needs to happen in here is for people to realize that talk about
three phase delta and wye circuits may be interesting, but it's noise in
here. We DIY'ers recognize that there is three phase power available
for equipment that uses it, but it's not something that we need to know
about, interesting though it may be. And, while I appreciate the input
from the professional electricians in here, we all know that our brains
are excellent housekeepers and that what we don't use will soon be
thrown out to make room for stuff we will use. Three phase power, and
how to wire it is something my brain is just itching to throw out. It
needs the space for stuff it will use, like how to fix a fridge or
spread drywall joint compound smoother.

You are of course correct but lots of people who know very little or
just enough to confuse themselves keep dragging PHASE into discussions
about houshold electrics.
The normal houshold supply in the USA is ONE phase with a centre tap
grounded to produce 120 volts above ground and 120 volts below ground
or 240 volts between the ENDS :/

--
John G