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

From: Ken (___ken3_at_telia.com)
Date: 12/04/04 

Date: Sat, 04 Dec 2004 18:03:05 +0100

On 1 Dec 2004 07:48:48 -0800, shoppa@trailing-edge.com (Tim Shoppa)
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.

In Sweden -48V for POTS, and -96V for ISDN.