1963-Two phase three wire in NYC.
I had an apartment in Westchester County NY that had 120V/208V (2 of 3 phases). More recently I had another apartment (which was fairly new) also fed by 120V/208V (2 of 3 phases). It took a while for me to figure out why my experimental radios run off of 250V were underperforming until I measured line to line.
See http://home.netcom.com/~wa2ise/radios/aa5240v.html
