Path: utzoo!attcan!telly!lethe!torsqnt!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ulysses!smb
From: smb@ulysses.homer.nj.att.com (Steven M. Bellovin)
Newsgroups: comp.dcom.lans
Subject: Re: high speed networking between buildings
Message-ID: <12204@ulysses.homer.nj.att.com>
Date: 22 Sep 89 18:13:49 GMT
References: <4574@ursa-major.SPDCC.COM> <337@ai.etl.army.mil> <1130@svx.SV.DG.COM>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 24

In article <1130@svx.SV.DG.COM>, gary@dgcad.SV.DG.COM (Gary Bridgewater) writes:
[lightning horror stories deleted]
> If you do run wires in a lightning prone area consider trenching.

Lightning is quirky stuff, and damned hard to defend against.  I've
seen situations where long runs of cable within the same building
have ``attracted'' the attention of lighting bolts, frying the equipment
on either end of RS-232 lines.  

Based on my own experiences, I don't think buried cables -- I assume
that that's what you mean by ``trenching'' -- help that much.  When
I was in Chapel Hill, we regularly lost some gear connected by
cables that ran under the street.  We tried all sorts of protectors,
too; nothing seemed to help.  The problem was that in the time (and
at the voltage) the lightning protection devices took to act, it
was already too late -- the chips are just too sensitive.  We
eventually resorted to optoisolators; they'd get fried, too, but
it was easier and cheaper just to replace them....

For that matter, during one particularly severe storm, my TV was
fried via the cable TV input jack.  Of course, that strike was close
enough that it blew out a couple of light bulbs and even popped one
of my apartment's circuit breakers -- I'm not sure anything but a
Faraday cage would have helped against that one.