So now, with the advent of twisted-pair wire, where adjacent electrical
signals cancel themselves out due to the twists (how many per foot
matters), individually shielding wires became moot, and Cat-5
became as good as ABAM in short runs.
Telco's still use ABAM cables, where bundles are foil-shielded within
the central office. Twisted pair has not taken root as it takes up
precious conduit space. Once outside the c/o, the pairs are seperated
as far apart as possible along the run (but newer technologies like
HDSL have brought that engineering design need way down).
T-568B wired Cat-5 cables (which is the standard for so-called 10baseT
cables) work perfectly as the pairs for T-1 wiring (1+2 and 4+5) match
the twisted pairs in the scheme.
p.s.. Don't use T-568A wired cable (or god forbid, RJ11/RJ14 wired
cable). The twisted pairs will not match up. You will rarely
find this wiring scheme anyway outside of a computer network
environment anyway.
p.p.s.. If you are planning on a long run (500+), I'd consider using
ABAM cable of greater guage (like 24 or even 22). I did a 600
foot run on 22 guage ABAM (special ordered) for the INET
conference in a hotel in San Francisco, and the signal was
nice and clean. It's much better to over engineer than to
deal with the errors in the end equipment.
rob.
On Sat, Nov 15, 1997 at 05:31:34PM -0600, PM Mailing List wrote:
>
> I know this sounds like a stupid, newbie question, but oh well, I don't
> know where else to ask...:
>
> What is the exact type of cable that is used to connect the PM3 & the T1
> box (we ordered Channelized T1) that the phone company drags to your
> location? I assumed they were called T1span cables and ordered 2 of them
> as well as 2 ethernet (100baseT) cables from a local vendor. The 4 cables
> that were delivered were identical, so we tried all four. They all worked
> for both the ethernet & for the T1. Are these cables interchangeable?
> Thanks for in replies in advance.
>
> Sincerely,
> Thomas
>
>
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