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From: jbs@mit-eddie.MIT.EDU (Jeff Siegal)
Newsgroups: net.sci
Subject: Re: Choice of voltage?
Message-ID: <1199@mit-eddie.MIT.EDU>
Date: Thu, 6-Mar-86 09:00:38 EST
Article-I.D.: mit-eddi.1199
Posted: Thu Mar  6 09:00:38 1986
Date-Received: Sun, 9-Mar-86 08:23:43 EST
References: <drutx.107> <232@ccnysci.UUCP>
Reply-To: jbs@eddie.UUCP (Jeff Siegal)
Distribution: net
Organization: MIT EECS Dept.
Lines: 16

In article <232@ccnysci.UUCP> sukenick@ccnysci.UUCP (George ) writes:
>>Along the same lines, why -48 volts for telephone lines.  I understand
>>the negative voltage is to prevent loss of copper.  But 48?
>				^^^^^^^^^^^^^^
>Negative with respect to what? 

The ground, I would assume.

>If its negative to prevent
>some degradation (oxidation,perhaps?)of the copper,
> then what is the ground wire composed of?

This does not seem particualarly relevant, since its potential with
respect to the ground would be very small.

Jeff Siegal - MIT EECS