Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site watcgl.UUCP
Path: utzoo!watmath!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.lan
Subject: Re: inter-building ethernet grounding
Message-ID: <3017@watcgl.UUCP>
Date: Sat, 25-Aug-84 15:32:51 EDT
Article-I.D.: watcgl.3017
Posted: Sat Aug 25 15:32:51 1984
Date-Received: Sun, 26-Aug-84 00:42:32 EDT
References: <433@cornell.UUCP>, <1352@wateng.UUCP>
Organization: U of Waterloo, Ontario
Lines: 12

Direct lightning strikes will, of course, wreak havoc with an ethernet
cable.  But I believe previous respondents' concern with lightning strikes
was that a lightning strike on one building could momentarily raise that
building's AC ground potential considerably above that of nearby buildings,
thus causing ground currents between buildings via the Ethernet cable
if the cable was grounded in both buildings.  The solution, of course, is
to ground the Ethernet cable in one place.  But even then, the ground
potential difference could cause the normal isolation built into the
transceiver to break down.  (Anybody know what the minimum isolation is?)
And, of course, anyone working on an Ethernet cable in one building when
the cable is grounded in another building and there is a thunderstorm in
progress might get a nasty shock.