If your utility provider has a "star to star" xfmr (grounded conductor required) and you are feeding a 480/277v 3 phase main panel for a/c, heat and refrigeration only, are you required to pull a grounded conductor with the feeders? This particular situation includes an additional secondary set of feeders from main panel to 208/120v xfmr with taps for delta/wye (no grounded conductor needed) for lighting panel.
