[sdiy] question about cables

[aerogramma]

interesting!

I already use solid telephone wire for my projects (not for patch  
cables though), the reason being that is infinetely cheaper than any  
other multistrand wire I could find

So it's not a bad idead after all?

aero

On Aug 24, 2009, at 2:35 PM, Jerry Gray-Eskue wrote:

>
> Not many people have seen the inside of a central office.
>
> The telephone systems are designed and built using matched solid  
> wire twisted pairs throughout the system. This is the same wire  
> (with appropriate jackets) that runs on poles and underground all  
> the way to each customers house or business. They do make extensive  
> use of insulation displacement connections in punch down blocks and  
> other connector types. The entire system is designed for  
> reliability and ease of rerouting hardwiring, notably a lot of the  
> IDC is reused when wiring changes are made without a loss of  
> reliability. Even a small office has a nightmare of apparently half  
> hazard wire loom going to the main distribution frame, looking all  
> in the world like a huge demented spider had been randomly weaving  
> a web for weeks.
>
> One of the main reasons the wiring is all the same type is to  
> support resolution of problems with the copper pairs. The wire is  
> manufactured to a tight tolerance of capacitance, inductance and  
> resistance per foot as well as other characteristics. In particular  
> the capacitance per foot is used by automatic line test head  
> manufactures to locate a wire problem. For instance by measuring  
> the capacitance tip to ring, tip to ground, and ring to ground, it  
> is possible to identify a single broken wire and locate the wire  
> break within a few feet.
>
> - Jerry
>
> formerly with Reltec, Marconi, Emerson, Tollgrade - line test  
> divisions.
>