In the early 80's I worked for a large telco that used a magnetic drum storage device (yes I'm old.) The drum was used to store long distance billing for a very large geographic area. It was also powered through a standard wall switch right by the door. One night the cleaner went to turn off off the lights and also turned the drum as well. No one noticed until the next morning. A lot of people got free long distance that night.

It's not the cleaners fault, the blame remains on the idiot that decided that a wall switch without a mechanical guard was a good idea.