Centralized cabling

Q: I am involved in a cabling job that I am not sure will meet eia/tia standards. We have an unusual requirement that is causing us to put our fiber- serviced communications closets on the 14th floor to service the 14th and the 16th, with closets on the 12th to service the 10th and 12th, and so forth. We will have no drops on the 15th and 13th floors.

Q: I am involved in a cabling job that I am not sure will meet eia/tia standards. We have an unusual requirement that is causing us to put our fiber- serviced communications closets on the 14th floor to service the 14th and the 16th, with closets on the 12th to service the 10th and 12th, and so forth. We will have no drops on the 15th and 13th floors.

Because the cable runs to the wallplates on the remote floors are less than 100 meters, we have assumed that we could run Category 5 cable through conduits in protected areas on the unserviced floors, along the dropped ceiling on a floor to be serviced, and directly to the rooms.

Recently I have been told that eia/tia standards require risers to be fiber, but I can find no documentation to substantiate this. What are the facts?

Luis Zapata

Griot & Grito Computer Services

Silver Spring, MD

A: Many users of high-performance cabling systems are implementing data networks with centralized electronics rather than distributed electronics and are demanding that their cabling systems support this decision.

TIA/EIA TSB-72, "Technical Systems Bulletin on Centralized Optical Fiber Cabling Guidelines (October 1995)," discusses the concept of centralized cabling. Don`t be fooled by the title; TSB-72 is equally applicable to twisted-pair copper cabling.

Centralized cabling is a design alternative to the more traditional method of locating a horizontal crossconnect in the telecommunications closet on each floor. Centralized cabling permits you to install a cable from the work area to the centralized crossconnect by allowing the use of pull-through cables.

Here at the University of Texas at Austin we have elected to implement centralized cabling wherever possible. One ten-story structure has one equipment room, which backs up to the wire chase for the building. Category 5 cables are installed from each work area to the equipment room, and are terminated on Category 5 connecting hardware at both ends. This permits moving one patch cable to change a node from 10Base-T to 100Base-T.

In the case where the building is either too large or the pathways prohibitively long, we have installed multiple equipment rooms, linking them with fiber backbone cable for data and unshielded twisted-pair backbone cable for voice services.

Donna Ballast is a communications analyst at the University of Texas at Austin and a bicsi registered communications distribution designer (rcdd). Questions can be sent to her at Cabling Installation & Maintenance or at PO Drawer 7580, University of Texas, Austin, TX 78713; tel: (512) 471-0112, fax: (512) 471-8883

e-mail: ballast@utexas.edu.

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