From nanog:  (probably aprocryphal)

We tested our Y2k power contingency plans just over two weeks ago... we
didn't expect any downtime either.  We moved up the date on our power
systems and cut main power.

Three generators failed to operate. Two threw their breakers due to the high
load on them.  The last was overwhelmed when the previous two cut out and
threw an estimated 300 amp surge through the lines, blowing up hundreds of
light bulbs, frying fax machines and pencil sharpeners along the way,
jumping circuits in our industrial level surge protector and traveling
through our "surge protected" lines to every desktop in the company and into
the server room.  After taking out over 100 monitors and almost 40 PCs, the
surge proceeded to destroy our Server Room air conditioner, 4 huge APC UPS
systems, 4 Compaq Proliant 6500s, 9 Compaq Proliant 3000s, a Compaq Proliant
1800 and both AS/400s.

The surge then jumped the lines into the main power grid, blowing up two
transformers, one of which fell on the IT manager's car (poetic justice) and
cutting power on the entire block.  The generator then proceeded to burst
into flames, eventually blowing up all six generators and burning up seven
cars.

This all occurred within about 10 seconds and sent 38 people to the
hospital, got the entire IT staff fired (and me hired as the new IT
manager,) cost the company over $650,000 in equipment (not to mention the
impending lawsuits), destroyed 8 cars and has cost the company two weeks
(and running) of downtime.