The question came at work rather or not you have to install yuor neutral wires on the xo from the transformer to your main switch gear on a 480/277 volt y system one master told me no and the other master told me yes but neither one of them could tell were to find the answer in the code book so if any one knows the answer and were to find it in the nec i would like some input thank you
Assuming this MDP is not the service, and the system is grounded, but the neutral will not be used as a circuit conductor, IMO no, but a System Bonding Jumper will be needed to connect the EGCs to the Grounded Conductor, sized to 250.66.
If not the service, and the system is ungrounded, then no.
If the neutral will be used as a circuit conductor, then yes.
If the MDP is a service, then yes 250.24(C).