Ground rod for 3 phase 480 v generator

[J. Hofstetter]

I work for a company that owns 19 different stone quarries and/or sand & gravel operations and we currently have 3 portable plants. Two of these plants are entirely cord and plug connected and the third is a blending bin system which is simply 3 bins, a conveyor, a generator, and all of the motor controls mounted on a semi trailer frame. My question is if any of these plants would require a ground rod per the NEC? The way that I read the code is that they do not, but we recently had an inspector from MSHA (Mine Safety and Health Administration) give us a citation and a $3000 fine for not having a ground rod installed.

 

[zbang]

Was it for an NEC violation or an MSHA violation? As I understand it, the latter are much more strict.

 

[J. Hofstetter]

It was written as a MSHA violation. When the inspector was questioned he said that it was according to the NEC, but he couldn't provide me with any additional info.