A commercial building has a WYE transformer for it's 120vac 1ph power. It has 4 wires going out:
L1 - Hot 120v
L2 - Hot 120v
L3 - Hot 120v
White - Neutral for 120v
Any two of the L1, L2, or L3 lines when hooked to power leads makes 208vac, not 120v. Why? They are 120° separation. Only when they run a 3 phase motor do they kick out 240v.
You do not use the Neutral on a 208 circuit. You would use a second Hot instead.