Derating Neutral

[Acerock21]

I am tapping an existing 500amp 480v feeder to feed a mcc with mostly motor starters. The feeder is parallel 500mcm alum. in 5" PVC 3ph 3w (2 x 500al/ph + 1 x #2cu gr). There are two 30amp breakers in the mcc that are going to feed packaging equipment from Europe. The vendor has requested a neutral for his equipment that will have no/minimal load, they just want a reference. I am going to attempt to pull a neutral through the existing conduit, what is the minimum size copper conductor that I can pull? Thank you in advance for your help.

 

[kwired]

I am tapping an existing 500amp 480v feeder to feed a mcc with mostly motor starters. The feeder is parallel 500mcm alum. in 5" PVC 3ph 3w (2 x 500al/ph + 1 x #2cu gr). There are two 30amp breakers in the mcc that are going to feed packaging equipment from Europe. The vendor has requested a neutral for his equipment that will have no/minimal load, they just want a reference. I am going to attempt to pull a neutral through the existing conduit, what is the minimum size copper conductor that I can pull? Thank you in advance for your help.

I think you are asking what is minimum size conductor required for this neutral that has little to no load.

The answer is in 215.2(A)(2) which refers you to 250.122.

So the smallest grounded conductor regardless of how much load it will carry has to be same size as minimum size required for an equipment grounding conductor.

This would be for the feeder, the branch circuit(s) I do not find such language in art 210, and other than household ranges, the grounded conductor size is not mentioned for branch circuits.