NGR - Ground wire connection sizing?

[Raptor1963]

Could someone please comment on how to correctly size the cable from the ground side of a neutral grounding resistor to the earth ground. This application is for a generator 2500kW, 4160VAC, 3PH, 60Hz......NGR sized at 200A, 10second rating

 

[Julius Right]

Although NER?s will operate for most of their life at or near earth potential, they have to be treated as high voltage devices in terms of insulation rating, testing and maintenance.
In my opinion, there are a few fault cases in which a phase- to- phase voltage could be present at both ends of NER.
So a 5kV cable with suitable terminations has to be provided .In my opinion, this cable has to be identical with the cable from generator neutral to NER.

 

[Smart $]

Under the NEC, if the GEC connects directly to the resistor, it is obviously sized per 250.66, as is the Equipment Bonding Jumper (EBJ). if the GEC is connected elsewhere, the EBJ is the same size as the neutral conductor (ampacity not less than the maximum current rating of the grounding impedance but in no case shall the grounded system conductor be smaller than 8 AWG copper or 6 AWG aluminum or copper-clad aluminum.") This is the minimum size requirement.