Patrick McLaughlin
Lauded by many as a concept that allows flexibility and mobility in the workplace, zone cabling was officially recognized by the Telecommunications Industry Association (tia--Arlington, VA) in October 1996, when the organization published telecommunications systems bulletin tsb-75, "Additional Horizontal Cabling Practices for Open Offices."
George Weller, senior principal engineer with Steelcase Inc. (Grand Rapids, MI), says zone cabling meets user requirements, including what he calls movable privacy. "If walls are knitted together with cabling, they are difficult to move," Weller says. "A consolidation point reduces the amount of cabling that needs to be dealt with in moving the walls." Even better, he says, a multiuser telecommunications outlet assembly (mutoa) removes nearly all cabling from office walls. When a mutoa is used, only patch cords must go through furniture.
Weller adds that zone cabling provides users with many connection points, each shared, with some of the flexibility supplied by routing cables through furniture.
According to Ken Hall, manager of systems marketing with amp Inc. (Harrisburg, PA), zone cabling is a solution for both a company`s information-services and its facilities-management departments. Zone cabling delivers the services required by information-systems personnel and returns flexibility to the furniture investment for facilities management, Hall says.
He adds that although the initial investment in zone-cabling materials is usually higher than the cost of traditional cabling methods, the ability to use 25-pair cable and high-strand-count fiber can reduce the time needed to actually install the system. Further, he says, payback of the difference in cost is typically achieved during the first move, because with zone cabling, moves, adds, and changes are more easily performed than with traditional cabling methods.
However, Bob Jensen, registered communications distribution designer (rcdd) and senior design consultant with dbi (Austin, TX), maintains that there are still some unanswered questions surrounding the zone-cabling approach. Some of those questions concern the use of 25-pair cable. According to Jensen, the tia has not recognized 25-pair cable as a horizontal-cabling medium. He also says that 25-pair connectors have not been standardized, nor have pin/pair assignments been agreed upon within the tia. Furthermore, many manufacturers of 25-pair Category 5 cable do not instruct users on how to break out individual 4-pair bundles to minimize crosstalk from other bundles.
Bryan S. Moffitt, distinguished member of the technical staff at Lucent Technologies (Murray Hill, NJ), says that zone cabling has advantages and disadvantages, but overall, it presents a viable option for many customers. He says the publication of tsb-75 strengthened the zone-cabling option and points out that the use of multipair cable in horizontal applications is gaining industry-wide acceptance. Zone boxes that can facilitate consolidation points in plenum spaces are also becoming more widely available, Moffitt says.
The information for this article was derived from "Do We Need Zone Cabling?", a panel discussion held at the bicsi Summer 1997 Conference in Providence, RI.
