I was once helping out by clearing a backlog of fault calls at a railway depot. Suddenly the PC I was working on went dark and all went quiet.
Enquiries revealed that someone up the road had chopped the BIG cable with an excavator, so it was not going to be a quick fix. I went to the server room and gave things a graceful shutdown before the UPS gave out. This was late afternoon after the office workers had left, so only the engineering staff were around. I headed over to them to inform them that I was heading off too, and commiserated with them that they would now be unable to brew any tea. "No problem" they said. "This buffet car gets its power from the overhead line".