Last week our guys had a blonde moment while setting a new 480/208 xfmr. They ran 5 wires to feed it with 480; 3 phases, neutral and ground. They attached the neutral to the X0 terminal along with the 208Y12 neutral. Once they woke up and realized we didn't need the neutral they just disconnected it and capped off both ends. Then the discussion started:
1) Is there any code violation to feed the neutral also?
2) Is there any safety or theory problem with the neutral?
3) Could they have just left it attached?
After a bunch of thinking and drawing this thing out, and staring at my Masters License, wondering if they really issued me that thing, I answered all these with a simple "I have no clue, but I know who to ask". Well people, you're it. Gimme your opinions.