Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!pasteur!ucbvax!noah.arc.CDN!kenw
From: kenw@noah.arc.CDN (Ken Wallewein)
Newsgroups: comp.protocols.appletalk
Subject: Re: Help: Localtalk schemes
Message-ID: <1856*kenw@noah.arc.cdn>
Date: 5 Jan 89 15:06:00 GMT
References: <3370@bgsuvax.UUCP>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 26


  I'm not sure about 3-pair cable, but I recently had an interesting
experience with both electrical and safety characteristics of the 2-pair
stuff. 

  We've been stringing 'temporary' Phonenet wiring through the ceiling.  We 
used standard phone wire (JKTN, or 'Jake').   I has asked the supplier for 
fire-safe cable, and through misunderstanding, he gave me wire with a (I 
believe) T-1 rating.  This is _not_ plenum rating; it is not legal for 
ceilings which are used for return air.

  It also turns out that JKTN wiring is not two twisted pairs;  all 4 wires 
are wrapped together, and twist is not really specified as far as I can see.

  I now have T-4 (teflon) plenum-rated 2 twisted pair cable.  It's called
'intercom' cable, and costs about 50% more that the telephone cable: still
cheap.  To me, it's worth it; I'm considering specifying such cable for all
future Phonenet wiring. I've had cases while running two Appletalk networks
using both pairs of JKTN wiring, where I suspected crosstalk between them. 
Using this 'intercom' cable would just about rule that out.  It is the same
guage as the JKTN stuff, but the outside diameter is slightly greater.

 /kenw
                                                                 A L B E R T A
Ken Wallewein                                                  R E S E A R C H
kenw@noah.arc.cdn                                                C O U N C I L