These pics were taken after the tenant left this industrial rental, and things were being made ready for the new tenant.
In the first pic, please note the flex in the middle of the pic.
The next pic gives another view of the flex, from below.
This place had a 'mystery switch' in the middle of a wall; the flex went from the switch, across the room, to a 30A 240V receptacle high on the wall. I have no idea what it was for. There was no ground wire, either.