In message , at 10:54:25 on
Mon, 29 May 2017, Scott remarked:

The power feed into the building is only the beginning of the sequence
of potential points-of-failure.

True. I thought of this after I posted. The 'power supply' in my
computer here is not the same as the power supply to my house.

Yes, I've got a 6hr laptop plugged into a UPS, which if the laptop power
supply was the only[1] sink would last another day. Mifi-style mobile
connectivity through a mast on a different substation, and that's most
of my continuity issues solved.

Doesn't scale to whole datacentres, though.

[1] About one minute's unplugging of other stuff.
--
Roland Perry