In addition to classicsat's info; in commercial, industrial and even some large apartment complexes we use 120/208 3phase wye. Industrial settings, with lots of lighting and large motors, will also have 277/480 volt 3phase. In our aparment complexes, seldom are all 3 pheses brought out to individual aparments. It is usually 2 of the 3 phases set up for 120V phase to neutral and 208V phase to phase.
