Xref: utzoo comp.misc:2733 sci.electronics:3223
Newsgroups: comp.misc,sci.electronics
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Protecting computer equipment
Message-ID: <1988Jul8.045005.17867@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1187@gmu90x.UUCP>, <152@limbic.UUCP>
Date: Fri, 8 Jul 88 04:50:05 GMT

> ... there's
> no real way of avoiding damage from lightning short of pulling the plug out
> of the wall socket and running things off batteries...

There's no positive way of avoiding damage from lightning.  Period.  Run
your equipment off batteries and line your walls with wire mesh to form a
Faraday cage, and if lightning feels like paying a visit, in it will come.
This stuff has just punched through *kilometers* of air -- an awfully good
insulator -- to reach the vicinity.  Nothing you can do will stop it if it
really wants to come in.  Lightning rods and the like are based on giving
it a more attractive place to go, not on stopping it from doing what it
wants.  If lightning is on your AC line, forget your computer and pray the
bolt doesn't come looking for *you*.

HOWEVER... direct lightning hits are rare.  More common is a nearby hit
that induces currents and voltages everywhere.  *That* can often be handled.
Things like surge protectors will at least improve the odds.  While those
things are often grossly overpriced, it is true that protection is usually
in some sort of proportion to cost.  Even a few MOVs and a fuse or two are
better than nothing.  Protection for phone lines is trickier, and is best
bought commercially, but it too does help.  Industrial-strength modems
often include their own protection, but hobbyist-grade junk is prone to
eliminating anything that costs an extra fifty cents.
-- 
Anyone who buys Wisconsin cheese is  |  Henry Spencer @ U of Toronto Zoology
a traitor to mankind.  --Pournelle   | {ihnp4,decvax,uunet!mnetor}!utzoo!henry