ground wire - resistance grounded

[tulum]

Hello all,

Typically we run a ground conductor on a feeder that is generally one size down from the phase cable size.

Since I work in mining, typically all the systems are resistance grounded and by code generally the MPC's have a main ground of #8awg....

Why do I run anything larger than this on the secondary feeders???

Regards,
TULUM

 

[tulum]

Sorry to explain further the systems generally have 5, 10, or 15A NGR's and the feeders are close coupled?

Regards,
TULUM

 

[dpc]

I think the NEC ground wire sizes are based only on the feeder rating. System grounding is not a factor. I suppose the concern is that a resistance-grounded system could be easily changed to solidly-grounded in the future.