That reminds me.
Years and years ago my department's intranet web server lived in the same office as the network manager (next to mine) as there was nowhere else to put it and it had a dinky UPS to keep it alive just in case.
However, when the time came, and some Thames Water workers accidentally cut the power cable for our building.
1. Everything goes dark with just the sounds of dying fans piercing the silence.
2. There is a loud explosion
3. The slightly singed Network Manager stumbles, coughing, out of his office in the midst of a cloud of smoke.
4. Smoke alarms go ape (thanks to PP3 batteries)
I have been wary of UPSs ever since