Actual height to ground isn't anything exceptional. The issue is that other stuff, such as production equipment, gets in the way. Then, supposing you get up there, the depth of the trusses puts the box out of reach of someone in a basket.

Even if you let a trained monkey scale the cable tray, the final run is off to the side, so you could not reach the box, or see inside.

I see no point in worrying about the fan itself, when we KNOW power isn't getting to it.

The original contractor put a 20-ft. little "Genie" 1-man lift atop one of the overhead cranes.

The fan assembly easily weighs 300 lbs, with nearly half of that for the motor alone. I proposed taking the fan apart and constructing a platform to hang either off the curb, or the trusses below.

I also proposed making a sled to transport equipment - like replacement motors- across the sheet metal roof. No dice, I was told- "Engineering" says we can't do that, because it's "not a structural roof deck." Yet, somehow, it's OK with engineering for me to put that 140# motor on my shoulder and walk across the deck!