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From: seltzer@opus.UUCP
Newsgroups: net.misc
Subject: Re: four versus two
Message-ID: <154@opus.UUCP>
Date: Tue, 30-Aug-83 14:02:05 EDT
Article-I.D.: opus.154
Posted: Tue Aug 30 14:02:05 1983
Date-Received: Thu, 1-Sep-83 05:56:28 EDT
References: <1037@msdc.UUCP>
Lines: 22

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