[conspire] A timely question.

[Rick Moen]

Quoting Paul Zander (paulz at ieee.org):

> So was I being overly cautious?

No.

What follows is from memory and written in a hurry, so it'll be rough.
Power fluctuations can be somewhat sloppily divided into:  surges,
spikes, and low-voltage conditions.  (Surges and spikes are both
high-voltage conditions but differ in speed, spikes being the rapid
ones.)

All three can hurt, but low-voltage conditions are the most common to
cause electronics damage and the least commonly corrected by
AC-filtering gear.  Spikes are the next most damaging and also seldomly
corrected by AC filtering.

Surges are trivial to intercept using thermistors in any old cheap piece
o'crud surge protector -- but are the least damaging to begin with.

Back in the '80s and '90s, $5 power strips were widely sold as 'surge
protectors' even though they lacked even the most basic features of that
sort.  I think that's less often done, these days.


Local risks:

Thunderstorms can directly cause spikes on the transmission lines and
local feeds.  PG&E's frantic switching during windstorms causing downed
trees and hence downed power lines and sometimes failed transformers can
cause all three types of problems.  In general, we have fewer problems
of power fluctuation than in places with more and more-severe storms.
It's also a bit less common (thank in some places) to have nasty amounts
of electrical noise (hence, spikes) on the AC line from nearby
industrial plants' AC backwash.

When my entire previous server was fried during a wind and thunderstorm, 
I have a strong suspicion it was mostly periods of low voltage while
PG&E was struggling to restore and maintain service that did in the machine.

Paul, as you're aware, I recently bought for $40 at the Silicon Valley
Electronics Swap a ham-grade AC line conditioner unit.  That's
_specifically_ because it's one of the rare sorts of AC-filtering gear
that detect and deal with low-voltage conditions.  Such gear should be 
viewed with some skepticism, as, if you don't, you will be unsure what
the thing _really_ does and end up with a supposedly magic box that
maybe does nothing more than block surges.