T1 demarc extension

A subcontract job I'm doing includes extending the T1 from the demarc to the telco equipment wall in the tenent's office suite. The contractor has provided CAT5e UTP and jacks for this purpose. From what I gather, this is not the proper cable to use, and I should be using either a cable with individually shielded pairs, or two separate cables, each with an overall shield - one for transmit and one for receive. Is this correct?

Also, from what I gather, the pairs in use are 1&2 and 4&5 on an

8-position jack? So, using the UTP provided, I wired the extension as T568B at both ends. Aside from any issues that arise related to my first question, should this work?
Reply to
Michael Quinlan
Loading thread data ...

You can use the Cat 5e cable, though using the shielded cable is the right cable to use. The cat 5e cable will cause more bit errors than a shielded cable, but, it will still work. A lot of talk has been on here before about it. You may want to use Google and search for more info on this cause I know there is a lot.

Reply to
Perkowski

Verizon used a 50-pair cable to extend 10 POTS lines into the suite, leaving 40 pair unused. I offered to use 4 of those to extend the T1, but the contractor wanted me to run a new CAT5e cable instead.

Thanks for the quick replies. Now I feel more comfortable going back on site tomorrow.

Reply to
Michael Quinlan

I did take a look. But my searches yielded a lot of unrelated messages, as the search term "T1" brought up almost all references to ANY wiring scheme, because of pair 1 being T1 & R1, pair 2 being... you get the idea.

Reply to
Michael Quinlan

The absolute very best cable to use is what you describe, individually shielded twisted pair cable. This is also referred to as T-1 screened cable.

Now back to the real world.

I install and extend special circuits for Verizon every day. We use Cat-5 cable for nearly all demark extensions nowadays. There is nothing wrong with using Cat-5 cable for T-1 extensions. Cat-5 cable works fine for 100 Megabit ethernet signals, a 1.5 Megabit signal should be no problem at all.

I've also installed and extended T-1's on regular 25pair cable with no problems at all.

Unless the environment is very EMI/RF hostile, or the extension is

*very, very* long, you should be just fine.

And yes, a T-1 circuit uses pind 1&2 and 4&5 the other pairs are unused.

John

Reply to
John P. Dearing

Try DS1.

Reply to
James Knott

What I would do if *I* was presented with that situation would be to split the T-1 between the two binder groups in the 50 pair cable. Put one side of the the T-1 in the white/blue binder and the other side in the white/orange binder. You only need two pairs for the T-1, not four.

Back in the old old days, T-1's were always put in separate binder groups to reduce cross coupling between transmit and recieve. Just make sure to clearly tag and protect the pairs you use for the T-1.

You really don't *need* a Cat-5 cable for T-1. It's only 1.5 Mb/s. Using Cat-5 is nice, but overkill.

As I said before, I install and repair these circuits every day. I've extended T-1's through over 1,000 feet of house cable and had the circuit work absolutely fine with no errors whatsoever. House cable is Category *nothing*. 8-)

John

Reply to
John P. Dearing

"John P. Dearing" wrote in news:OJuSd.28686$ya6.18028@trndny01:

CAT 5 cable should not be a problem when extending a T1 from a DEMARC . It is not the cable itself that determines the cable selection/design. Rather it is DS1 signal loss that determines if TX/ & RX pairs must be isolated from each other.

With a 0.0 to -7.5DBDSX T1 hand off level by the Telco at the DEMARC, A T1 can be extended for a reasonably long distance as long as the insertion losses of the cable @ 772KHz are not excessive enough as to allow signal cross talk from one transmission pair (Strong signal) to the other (Weaker signal) to occur.

Twisted 25 pair cable is OK for relatively short runs, however if used on house riser, it is reccomended that different 25 pair binder group pairs be used to isolate T1 RX/TX pairs.

Bill

Reply to
Bill

Michael,

take a look at the knowledge base article # 2374 on Kentrox's web

site. it covers this issue very well.

formatting link

service and support tab

Tech Support Knowledge Base

search for 2374.

Reply to
rimrock

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.