:: sigh ::
Here we go again!
Using two wires of a 3-phase is not technically "single phase", as each lead has a different offset frequency starting point. It could be called "poly" (strange I guess) or "multi" phase... but actually, the end result is the two wires are nearly always used to feed single phase loads, whether they are 220V or 110V.
The phase difference is there, but it is irrelevant.