480/277Y Panelboard

[powersoff]

I have a 1600A panelboard that is fed via a 2500kva transformer that is rated 480/277v on the secondary.
The panelboard does not have any loads that need a neutral.
Is it required to run the neutral conductor from the X0 of the transformer to the panelboard to satisfy NEC?
Thanks

 

[davidbeach]

If you ground XO at the transformer and run an equipment grounding conductor to the panel, no. If you don't ground X0 at the transformer, you need to connect X0 to the neutral bus at the panel and then ground the neutral at the panel. In short, you need four conductors (of how ever many wires in parallel) between the transformer and the panel, but the fourth could be either neutral or ground.

 

[rbulsara]

To add to davidbeach,

If this is a service entrance equipment, you do need to bring the N at least up to the main device to meet the code. There the same conductor will act as EGC as well.

Rafiq Bulsara

http://www.srengineersct.com