On Tue, 24 Jul 2018 03:46:47 +0000 (UTC), danny burstein
wrote:

Yes, there are ways to tap a transformer so that
"hot" to "hot" in these will get you 240VAC. But
my head hurts when thinking of them.

It is not complicated, they just use delta instead of wye secondaries
The flaw in that plan is you only get two 120v circuits out of your 3
phase service. The 3d (red/wild) leg will be 208 above ground but you
can still use all three to run your 3 phase loads (at 240v line to
line). This is fairly common in industrial bay installations where
most of the load is single phase but they still have a significant 3
phase load to serve.
The PoCo likes it because they can do it with 2 transformers.
http://gfretwell.com/electrical/3p%20delta%20vee.jpg
Typically the red leg transformer will be smaller than the one feeding
the single phase loads.
http://gfretwell.com/electrical/red%...ansformers.jpg

If you see 3 equal size transformers, it is usually 3p wye. (208)
http://gfretwell.com/electrical/3%20p%20wye-wye.jpg