all the 120 / 208 3 phase systems i've seen are 120v phase to ground (on all 3 phases) or 208 volts phase to phase, lota schools, older small grocery stores ect. around here have the 120 208 3phase systems. but most of the 120/240 3 phase systems have a wild leg (if not all 120/240 3 phase systems i've seen do) so 2 phases of a 120/240v 3 phase systems are 120 v to ground, and one of the 3 phases (the wild leg/high leg as we call it) are around 208 to ground. but any 2 phases of a 120/240 3phase system phase to phase is 240v. hope this helps.