"Martin H. Eastburn" writes:
Your one high voltage (really medium or somewhat low for service) is
a single phase of a larger 3 phase system.

Yes, I'm well aware of all that. Heck, I know how to *make* those
transformers.

The secondary is then generating single phase voltage - but if there
is a center tap, then the far two ends of the secondary with
reference to the center tap are out of phase and typically 180
degrees.

Typically? What, on alternate Tuesdays it's only 170 degrees?

This is 220 service.

No, it's 240 service.

There are unique transformers that can generate twisted star
voltages and phases

No, they can *convert* voltages that are already three phase to other
three phase voltages. They come in delta and wye configurations. An
isolation transformer can extract one of the phases and yield a single
phase service, but no simple transformer can turn N phases into N
phases.

but the are not at homes.

Maybe not *your* home.