paul@msdc.UUCP (08/27/83)
Can anyone out there explain why the phone company insists upon
using four conductor cable for telephone set installation when
it is apparent that only two conductors are required for the circuit?
(I just saw an installation of 5 single-line phone lines wired to
modular jacks with all 4 wires carefully attached to the jack and
upon tracing them to the connection block, noted carefully that
the black and yellow wires are neatly wrapped around the cable and
not connected.)
Please reply by mail. Thanks.
Paul Manno
Medical Systems Development Corp.
...!{sb1,emory,gatech,mcnc}!msdc!paulseltzer@opus.UUCP (08/30/83)
Telephone companies almost always install 4 conductor station wiring instead of single pair. A long time ago, some Bell Labs economics group figured out that it was the best long term thing to do. The spare pair are used for a couple of things: - Power for dial lights (although most new phones run off the line) - Additional line - Party line stuff (the yellow wire is used for a ground) - Replacement for the RED/GREEN pair when they fail At least in the past, the telephone company owned, installed, and serviced station wiring at their expense. Although most of the 2-pair station wiring installed is only using one pair, it works out that the high labor cost of installing additional wire for the above applications offsets the high cost of the 2-pair. That doesn't really seem right, but the labor costs are really high (and maybe higher when this strike ends ??) Wayne "not-a-phone-man-anymore" Seltzer just an engineer at NBI Inc. Boulder, CO ..nbires!seltzer
stevea@uiucdcs.UUCP (08/31/83)
#R:msdc:-103700:uiucdcs:10600118:000:416
uiucdcs!stevea Aug 30 14:42:00 1983
It could be for ease of installing another line, also the yellow wire used
to ring the bell, it is news to me that it doesn't do so anymore. Also,
on phones with lights in them, the black and yellow carry the power from
the little wall transformer to the light bulbs.
Steve Alexander
University of Illinois at Urbana-Champaign
...!{parsec,pur-ee,ihnp4}!uiucdcs!stevea
stevea.Uiuc@Rand-Relaypaulp@tekcad.UUCP (08/31/83)
#R:msdc:-103700:tekcad:7600017:000:463
tekcad!paulp Aug 30 09:59:00 1983
Those extra two wires save a lot of hassle when installing another line
as I did for my modem. It's also used to carry the 18v DC for lighting
dials and the like, e.g., Princess phone (probably copyright of WE).
Paul Pomes
Usenet: {ucbvax,decvax,pur-ee,ihnss,chico}!teklabs!tekcad!paulp
CSnet: paulp@tek
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US Mail: Paul Pomes, Tektronix, Inc.
Box 500 MS 59-323, Beaverton OR 97077
Phone: 503-627-2341