We have had similar discussions in the past, and, as a reminder:
- OSHA rules and NEC requirements differ;
- Until the early '90's there were practically no electrical lock-out devices made;
- Such devices often don't work on older equipment; and,
- There is a lot of perfectly good equipment out there that was made before LOTO was an issue.
So what did we do back then? Most often, we opened the box, disconnected the wires, and maybe taped a sign up. If there was any doubt, we also disconnected the wires at the machine.