I was gobsmacked yesterday (lots of US members will be googleing that one)!
A rack mounted Dell UPS had an overload error and just tripped out everything that was running off it. No putting them on bypass and sending an alert / triggering a graceful shut down, just cut the power.
I'm told that the cause of the problem was someone plugging their laptop into it which caused the overload (- seriously!). I didn't buy or specify this unit but my already slim faith in those that did is now non-existant!