Are you prepared for your customer's next wholesale personnel move?

To remain competitive in today's global economy, companies regularly assemble employees into special teams to undertake specific projects. This forces them to relocate personnel within a facility according to a specific business plan. As these assignments change, the layout of movable partitions and furniture in an office is also likely to change. And as the furniture and walls move, so too must the supporting network cabling.

The construction industry follows the TIA/EIA-568 Commercial Building Telecommunications standard for the design of telecommunications and network cabling in an office building. It defines not only how the installed cabling should be constructed and how it should perform, but also how the cabling should be distributed throughout the building. This standard has been revised twice, and 568-B is the most recent version.

UTP copper cabling is commonly used for the horizontal cabling run that extends from a communications room located on the office floor to the wall outlet that serves a workstation or desk located on the same floor. The horizontal cabling is installed in a physical star typology. In other words, each work area telecommunications outlet/connector is wired to a horizontal cross-connect (HC) in a telecommunications room (TR). Its own dedicated four-pair, 100-ohm, UTP copper cable extends from the HC in the TR and serves every workstation (Fig. 1). The length of the cable run is limited to about 300 ft. This cabling extends horizontally along the floors, walls, or ceilings.

The original standard included a method for avoiding the unnecessary expense of redoing the entire horizontal cabling from the telecommunications closet to each workstation whenever a change is made in the layout of one or more workstations in an office. In this case, the TIA first addressed the subject of open office cabling in its Telecommunications System Bulletin TSB-75, issued shortly after the 568 documents first became a standard. In other words, it shouldn't be necessary to rip out the existing conductors, install new ones, and re-terminate the wires at a workstation when conducting moves, adds, or changes.

In the past few years, new telecommunications technology has spawned higher performance cabling, new ways to connect that cabling, and higher-speed network switching. These emerging technologies foster the need for a cabling layout/design concept called zone cabling, or zone distribution. Such a design offers the telecom manager improved networking performance and an attractive return on investment whenever moves, adds, and changes are necessary.

Zone cabling focuses on two areas, one of which is the insertion of a piece of equipment within the horizontal cabling run and placement of some “active” network equipment — usually installed in the TR — within the office area. Active equipment is powered, as opposed to passive equipment like a cross-connect field. One such project would involve extending the fiber backbone cabling into the work area before converting the network cabling to copper cabling for the horizontal run. For these conversions, a piece of electronic equipment converts the fiber's light signal into an electrical signal for the UTP cabling. Installing optical fiber cabling onto the office floor and close to the workstations is often a viable option, especially when you're working with high-speed networks.

Zone cabling also involves inserting an intermediate point somewhere in the horizontal cabling run in the office area close to workstations that allows for reconnection or reconfiguration of conductors within that defined area. Four building columns usually enclose this intermediate termination point, allowing it to serve six or eight workstations from one point. The intermediate point in the horizontal run is either a multi-user telecommunications outlet (MUTOA) or a consolidation point (CP).

The 568-B.1 standard describes a MUTOA as a grouping in one location of several telecommunications outlet/connectors (Fig. 2). This type of assembly or mini-enclosure allows you to change an open-office layout without disturbing the horizontal cable. When MUTOAs are used, multiple horizontal cables are terminated in a sturdy enclosure at a common location, such as within a furniture cluster or similar open area. Then work area cables originating at the MUTOA are routed through work area pathways and modular furniture, among other things, and are connected to work area devices. A single MUTOA should serve not more than 12 work areas, and the enclosure should be fully accessible.

Equipment cords used with MUTOAs may be longer than the maximum length of 16 ft used in a typical installation. The 568-B.1 standard allows for longer equipment cords when the horizontal cable run from the TR to the MUTOA is less than 295 ft.

Telecom specialists caution that a MUTOA must be rated for the purpose. Thus, if the product is to be installed in a plenum environment, it must comply with National Electrical Manufacturers Association (NEMA) standards.

The 568-B.1 standard describes a CP as a location for interconnection between horizontal cables that extend from building pathways and horizontal cables that extend into work area pathways (Fig. 3). A CP differs from a MUTOA in that it has an additional connection within the horizontal cable.

A single-ended modular cord constructed with solid cable is necessary for making the connection from the CP to the work area. The modular plug is mated to the outlet in the CP and the other end is terminated to the back of the outlet in the work area.

For twisted-pair cabling, the CP should be located at least 50 ft from the TR to minimize reduction in signal quality. Again the CP must be in a fully accessible, permanent location, such as a building column or a permanent wall, and preferably within a lockable enclosure.

As often as office workers change locations within buildings these days, it's becoming increasingly important for network managers to have a system for adapting the office cabling infrastructure to adapt to the moves, adds, and changes. Zone cabling allows network managers to reduce the expenses involved with that constant state of flux, and for those situations where it won't work, the revised TIA-EIA 568 standard can help to streamline the inevitable network changes in the office environment.