Re: Why -48V for telephone lines, and not positive?

From: Tim Shoppa (shoppa_at_trailing-edge.com)
Date: 12/01/04 

Date: 1 Dec 2004 07:48:48 -0800

Winfield Hill <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote in message news:<coisj00l0a@drn.newsguy.com>...
> JeffM wrote...
> >
> >> when this stuff was invented
> >
> > Yup. Stroger Switches were invented in 1884--by an undertaker.
>
> Do you think they used -48V back then?

It was less standardized. Short loops were as little as -12V, long
loops could be more than -48V. It depended on who was selling the
switch and equipment too.

Large parts of the civilized world use -24V as the default on telco
loops.

Tim.

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