It's not an industrial setting - it's a mining operation. Mining operates under a different set of rules. I don't know them, so I can't comment
From my 'gut feeling,' 60 amps seems a lot for #10, and I never have liked 480 or 240v "two hots" circuits.
Oddly enough, the GEMS data would have revealed this problem- at the end of the line, a direct short to the ground wire would not draw enough power to trip the breaker. I'll bet the lights weren't working that well.
