Gentlemen:
For what it's worth, I faintly remember going to the Philadelphia area, a long time ago, with one of the "old timers".
I think it was some type of hotel, and it had two phase power. Can't remember all of the details; something about "2 hots, 2 neutrals, & 1 grd" maybe?????
Had to be in mid 70's???

John


John