I must be missing something, but I've never heard of a two mile run of 10 gauge wire. A lot went wrong with this install, but two miles of 10 gauge wire?!?!? Help me out here, am I reading this right?

The report mentions that line voltage was maintained with transformers, but what I have never heard of was that long of a run, in re: resistance.

"In order to maintain line voltage, two Acme Electrical Corporation boosting transformers were inserted in the circuit at six separate locations. Placement was determined by the drop in line voltage from 480 VAC down to 440 VAC, phase to phase."

Is this unusual in an industrial setting?

Mining accident report

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.