Xref: utzoo comp.dcom.lans:987 comp.dcom.modems:1318
Path: utzoo!mnetor!uunet!husc6!cfa!wyatt
From: wyatt@cfa.harvard.EDU (Bill Wyatt)
Newsgroups: comp.dcom.lans,comp.dcom.modems
Subject: Re: Fluorescent lights and data cables
Message-ID: <865@cfa.cfa.harvard.EDU>
Date: 28 Jan 88 23:23:46 GMT
References: <5253@columbia.edu>
Organization: Harvard-Smithsonian Ctr. for Astrophysics
Lines: 32


> 	[...]  The architects have given us a cable-routing scheme 
> 	utilizing cable trays along hall-way walls.  Their scheme seems
> 	acceptable to us except for one point:  the cable trays will be mounted
> 	in an aluminum tray above the hallway lights (they are flourescent,
> 	I believe).  The question I have is will the fluorescent lights
> 	cause interference along the data lines?  Is the aluminum tray
> 	an adequate shield?  The architects have never installed a cable
> 	routing scheme like this so they can't give us any references.
> 	We will probably run RS-232 stuff and perhaps twisted pair ethernet
> 	abd appletalk, and probably others in the cable tray.

I can't actually comment on the above question, but I have a warning
that may not have occurred to you: Make SURE you have separate
circuits for your computers and other quiet power units (including
separate GROUND at the outside water main or whatever) that isolate
from the lights and other noisy equipment. 

In our building, built in 1972-3, the fluourescent lights leak a
voltage into the neutral wire, so that there's 1.5 volts between the
neutral and ground. This is usually OK, but can apparently affect the
life of our computers. Since DEC specifies a limit of 0.7 volts, we've
sometimes had hassles with field service over the issue.
Unfortunately, rewiring is completely out of the question. 

-- 

Bill    UUCP:  {husc6,ihnp4,cmcl2,mit-eddie}!harvard!cfa!wyatt
Wyatt   ARPA:  wyatt@cfa.harvard.edu
         (or)  wyatt%cfa@harvard.harvard.edu
      BITNET:  wyatt@cfa2
        SPAN:  cfairt::wyatt