Path: utzoo!utgpu!watserv1!watmath!att!linac!uwm.edu!zaphod.mps.ohio-state.edu!caen!hellgate.utah.edu!basset.utah.edu!haas
From: haas%basset.utah.edu@cs.utah.edu (Walt Haas)
Newsgroups: comp.dcom.lans
Subject: Re: Lightning protection
Message-ID: <1990Nov29.094510.19209@hellgate.utah.edu>
Date: 29 Nov 90 16:45:10 GMT
References: <398@alsys1.aecom.yu.edu> <69636@bu.edu.bu.edu>
Organization: University of Utah CS Dept
Lines: 25

In article <69636@bu.edu.bu.edu> kwe@buit13.bu.edu (Kent England) writes:
>In article <398@alsys1.aecom.yu.edu>
> bob@alsys1.aecom.yu.edu (Bob Lummis) writes:
>>Does anyone have a recommendation for lightning protection on 10Base-T
>>links that go through a direct-buried cable between two buildings?...
>	This is really a very bad idea...
>	If you want to use 10BaseT, it would really be much better to
>use a pair of fibers and a pair of fiber optic transceivers between a
>couple of 10BaseT concentrators, one in each building.  The fiber
>provides excellent ground isolation between buildings, which is the
>problem you are really addressing.  Fiber also is not susceptible to
>lightning strike induced potentials...
>	Perhaps some of the many many people I have talked to over the
>years about these sorts of problems will speak up and confirm my
>position.  Don't make the same mistake.  10BaseT is a *local* medium. 

OK, sure.  We have a conduit between two buildings maybe a hundred feet
apart.  Computer in one building, terminals in the other.  Somebody
(not me) pulled copper wire for RS232 connection.  Next electrical storm
hit the hill near the buildings, produced a big enough ground potential
difference to fry all the transistors in the RS232 interfaces.  They
asked me what to do.  I said put in a fiber link with RS232 converters
at each end.  They did.  End of problem.

-- Walt Haas    haas@ski.utah.edu