It’s obvious that fiber optics is not copper wiring. Advantages of fiber include the capability of going longer distances at higher speeds, plus immunity to electromagnetic radiation. These advantages overcame its cost disadvantage and made it the cabling choice for telecommunication and CATV. While fiber is still struggling for equality in the premises cabling market, new methods and components are increasing its acceptance.
From the beginning, the fiber contingent was slighted by the TIA/EIA committee that wrote the “568” standards around copper wiring. There was no logical reason to limit fiber to UTP-copper architecture. While copper was technically limited to 100-meter links, fiber could go 2,000 meters or more. But the architecture of 568 was written around copper, with a backbone cable to a telecom closet connecting the desktop over a horizontal cable of no more than 100 meters.
Several years ago, fiber’s capabilities were recognized by 568 with the addition of a centralized fiber-architecture standard. The standard covered a network architecture that would place fiber hubs in the computer room and run backbone fiber to the telecom closet (now often called a room), then through passive interconnects to the desktop. By allowing a direct-to-desktop connection, there was no need for electronics in the telecom room. This meant that a data ground, conditioned and uninterruptible power, and air conditioning were also not needed, greatly reducing customer cost and making fiber cost-effective compared to copper.
The copper people learned a lesson from fiber and created zone cabling, which adds an additional consolidation point near desktops. Rather than the usual run of up to 90 meters of permanently installed horizontal cabling using a single cable for every desktop, zone cabling uses a backbone cable from the telecom closet to the consolidation point and short individual cables to the desktop.
Zone cabling creates a “mini-telecom closet” near the user, a terrific solution for modular-furniture designs that include cable pathways. When the offices move, the furniture can be unplugged and moved, but the wiring from the telecom closet to the consolidation point remains for future use. The modular furniture can be moved to another point where it again connects to a local consolidation point.
Another useful gadget is the multiuser telecom outlet assembly (MUTOA), a patch panel or box with up to 12 connections that can be installed near a number of users who connect to it instead of a wall outlet. With proper design, it not only simplifies installation, but makes moves, adds and changes much easier.
There can be a big advantage in installation, where only one cable is pulled to an area, and shorter cables are then used to connect to desktops. This works for fiber optics and multipair telephone cabling, but may not be possible for all copper-data cabling. For example, one can buy 25-pair Category 5e cable, but not Category 6. If the user decides to install Category 6, the cable runs to the zone box must be individual Category 6 cables.
Fiber optics and zone cabling work well together. Using multifiber cables, a single cable can connect multiple desktops to a backbone cable with minimal bulk and weight, often a big problem in offices with many desktop connections. Overhead cable trays can become filled with many Category 5E or Category 6 cables, but one small, lightweight fiber cable can connect dozens or even hundreds of desktops.
Zone cabling also works well with preterminated fiber optic cables. Cables can be factory-terminated and the connectors enclosed in a protective boot for pulling. After the cable is pulled and secured, the boot is removed and connected to the zone box or MUTOA, and the cable is ready for use.
These preterminated cable assemblies offer several advantages. They are faster to install and connectors have no yield problems, since every one is factory-made and tested. The components’ total installed cost is often less than field termination, but the customer’s price is the same, so they can be more profitable for the contractor. They do, however, require more care in installation to prevent connector damage.
Customers choose zone cabling for fiber to the desk applications because it reduces cable clutter and saves them money. It is not hard to design such a network if you know the basic layout and choose cabling hardware early in the process. Cable installation is easy, since fewer cables are required, but may require additional terminations at the zone boxes or MUTOAs. Like all installations, careful planning will yield an easier, neater installation. EC
HAYES is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at www.JimHayes.com.