Q: What does the Telecommunications Industry Association/Electronic Industries Alliance (tia/eia--Arlington, VA) mean when it says that "no more than three horizontal crossconnect points are allowed per run?" Is a patch cord two points or just one? Or is it not counted? Is a 25-pair Amphenol cable plugged into the front of an ibm 8260 hub considered a crossconnect point?
Daniel L. Fisher
Foundation Health Systems Inc.
Rancho Cordova, CA
A: When the tia speaks of a cable run, it can mean either a basic link or a channel. The basic link includes up to 90 meters of horizontal cable, a telecommunications outlet or connector, an optional transition connection or consolidation point close to the work area, and one piece of connecting hardware in the telecommunications closet (TC).
The channel includes up to 90 meters of horizontal cable, a work-area equipment cord, a telecommunications outlet or connector, an optional transition connection or consolidation point close to the work area, and two pieces of connecting hardware in the TC. The plug and jack connections to the hub equipment in the TC and the network interface card in the work area are not included in the channel.
A patch cord is a length of cable with connectors on one or both ends used to join telecommunications links at the crossconnect. A patch cord is not a connection point, but it can certainly be used to connect two pieces of connecting hardware.
A connecting block, consolidation point, or work-area outlet counts as one connection. A patch panel (or cross- connect), linked by patch cords, counts as two.
You`ll soon be seeing "helpful hints" from cabling manufacturers stating that if you are going to be installing Gigabit Ethernet on your Category 5 cabling and the channel is failing, then try interconnecting the equipment cord to the horizontal cable rather than crossconnecting, thereby reducing the three-connector channel to a two-connector channel. Great advice, but how do you cure an ailing three-connector link? First, change from a crossconnect to an interconnect, then test. Still not passing? Upgrade the connecting hardware from Category 5 to enhanced Category 5 or better, one piece at a time, starting with the work-area outlet and testing after each change. Still not passing? Time to upgrade the cable. My, that certainly seems like recabling, doesn`t it?
Donna Ballast is a communications analyst at the University of Texas at Austin and a bicsi reg-istered communications distribution designer (RCDD). Questions can be sent to her at:
Cabling Installation & Maintenance, or at
PO Drawer 7580,
The University of Texas,
Austin, TX 78713;
tel: (512) 471-0112, fax: (512) 471-8883,