Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rutgers!ames!ucbcad!ucbvax!SEISMO.CSS.GOV!kitty!larry
From: larry@kitty.UUCP
Newsgroups: comp.dcom.telecom
Subject: Submission for comp.dcom.telecom (Use of shielded cable for telephones)
Message-ID: <8705230318.AA03545@seismo.CSS.GOV>
Date: Fri, 22-May-87 23:18:45 EDT
Article-I.D.: seismo.8705230318.AA03545
Posted: Fri May 22 23:18:45 1987
Date-Received: Sun, 24-May-87 04:48:51 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 32
Approved: telecom@buit1.bu.edu

In a recent article dbj@RICE.EDU (Dave Johnson) writes:
> I need to wire a new phone line through a house for use with a modem.
> Is there some kind of sheilded phone cable that I could use to help
> reduce any noise in the connection?  Anything else I should be aware
> of when routing the wire such as not getting too close to electrical
> wires?  Thanks.

	I can think of no valid reason to use shielded telephone cable
for wiring in a house.  Most AC powerline noise is imposed upon telephone
lines through induction rather than conduction or radiation, so any
conventional shielded cable won't help this situation anyhow.
	Furthermore, the relative exposure of inside telephone wiring to
AC powerlines is insignificant when compared to outside cable plant exposure
to the electromagnetic fields of high-voltage AC transmission lines.

	Shielded cable is only useful for high-speed twisted-pair LAN
devices or other high-speed data lines (56 kbits/sec or greater).

	I have only two suggestions for your wiring:

1.	Try to find two-pair "inside station wire" which is _truly_ paired.
	Many two-pair station cables have four wires which are NOT paired,
	and therefore have some susceptibility to noise pickup and crosstalk.
	I wouldn't lose any sleep if you can't find such cable, however.

2.	Try to keep at least a 2 inch separation between telephone cables
	and any powerline wiring.

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
<>  UUCP:  {allegra|ames|boulder|decvax|rocksanne|watmath}!sunybcs!kitty!larry
<>  VOICE: 716/688-1231        {hplabs|ihnp4|mtune|seismo|utzoo}!/
<>  FAX:   716/741-9635 {G1,G2,G3 modes}    "Have you hugged your cat today?"