Gwaithcoed has probably solved it for you but, and this is probably something you have thought of, as it is in an education environment, are the extra wires for a remote emergency stop? In education workshops I have seen there are stop buttons at strategic points around the room. However, in my experience they cut off the whole shop supply not each machine individually.
Could it be something cleverer to keep the braking system (assuming one is fitted) working?
Regards
Graham