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Extending T1 from demarc via 25-pair

Extending T1 from demarc via 25-pair

(OP)
I need to extend a T1 from demarc in basement to my suite on 1st floor - rooms are basically directly above/below each other. There is a 25-pair cable between the two rooms with only the white/blue, white/green and white/orange pairs being used. Suggestions/recommendations on how to extend the T1 using the open pair? I believe I only need 2 pair but should I use consecutive pairs?

RE: Extending T1 from demarc via 25-pair

For best results, use pairs in different color groups to minimize crosstalk. For such a short distance, it'll work just fine.

RE: Extending T1 from demarc via 25-pair

Here is a link to the normal color code
For best results use an A wire and a B wire in each pair as they are twisted to reduce interference





RE: Extending T1 from demarc via 25-pair

(OP)
Thanks. So it would go like this?
Black/blue = pin 1 = transmit
Black = pin 2 = receive
Yellow/blue = pin 4 = transmit
Yellow = pin 5 = receive

RE: Extending T1 from demarc via 25-pair

Yes, but there is no "black" or "yellow" - the Ring conductor is the complementary to the Tip.

So you want to use

Black/blue = pin 1 - receive Tip
Blue/Black = pin 2 - receive Ring

Yellow/blue = pin 4 - Transmit Ring
Blue/Yellow = pin 5 - Transmit Tip

RE: Extending T1 from demarc via 25-pair

(OP)
Thanks for clarifying the blue/black and blue/yellow. I was lazy in my typing. In your example is Pin 4 Ring and Pin 5 Tip? I thought is was the opposite.

RE: Extending T1 from demarc via 25-pair

It should not matter about tip and ring any more as most equipment has diodes in it now to determine the polarity for you.

RE: Extending T1 from demarc via 25-pair

@sbcsu - with a T1 circuit, polarity is VERY important. It's only four conductors, but they need to be spot-on.

RE: Extending T1 from demarc via 25-pair


As long as you have the first pair connected to the first pair connections and the second pair to its connections then it will work - that is there is no polarity inside the pair itself - but this does depend on the modem/supplier box that you are connecting it to

RE: Extending T1 from demarc via 25-pair

In my day, "gray" was called "slate". I was surprised to see "gry" in you color code table. ;)

Jim

RE: Extending T1 from demarc via 25-pair

Yes Slate is what I remember as well.
It's probably an international color/colour code....

RE: Extending T1 from demarc via 25-pair

In the old days before cat-3 and cat-5 cable we extended t-1's using non-consecutive pairs. I don't know if we need to or not we just did it. If you have cat-3 or cat-5 tie cable you can use consecutive pairs with no problem.

RE: Extending T1 from demarc via 25-pair

I have to agree that the polarity is important!

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