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From: johnsson@decwrl.UUCP (Richard Johnsson)
Newsgroups: net.lan
Subject: Re: inter-building ethernet grounding
Message-ID: <3430@decwrl.UUCP>
Date: Fri, 24-Aug-84 12:38:21 EDT
Article-I.D.: decwrl.3430
Posted: Fri Aug 24 12:38:21 1984
Date-Received: Wed, 29-Aug-84 01:24:45 EDT
References: <433@cornell.UUCP>
Organization: DEC Western Software Lab, Los Altos, CA
Lines: 17

The Xerox Palo Alto complex of buildings had a lightning induced Ethernet
failure several years (which probably led to the emphasis on grounding in
the Blue Book).

Basically the cable became grounded in two buildings about 500 feet apart
by cable taps accidentally touching metal cable trays. A nearby lightning
strike induced a large, temporary potential difference between the buildings
and fried several tranceivers. Unfortunately about six of the tranceivers
died shorted rather than open and we had a lot of fun learning how to
use a TDR to find them.


	Richard Johnsson
	DEC Western Software Lab, Los Altos, CA  (415) 949-1494
	{decvax,ucbvax,ihnp4,allegra}!decwrl!johnsson
	johnsson@DECWRL.ARPA
	RHEA::JOHNSSON