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As uses for fiber have become more varied, manufacturers have begun producing cables to meet specific needs. Cable configurations vary based on the type of use, the location, and future expansion needs, and it is likely that more will be created as future applications emerge. Bear in mind that different cable arrangements are variations on a theme. Different combinations of buffer type, strength members, and jackets can be used to create cables to meet the needs of a wide variety of industries and users. Let’s look at some of the commonly available optical fiber cables.
Distribution Cable
When it is necessary to run a large number of fibers through a building, distribution cable is often used. Distribution cable consists of multiple tight-buffered fibers bundled in a jacket with a strength member. Typically, these cables may also form subcables within a larger distribution cable.
Distribution cables usually end up at patch panels or communication closets, where they are hooked into devices that communicate with separate offices or locations. These fibers are not meant to run outside of office walls or be handled beyond the initial installation, because they do not have individual jackets.
Distribution cables often carry up to 144 individual fibers, many of which may not be used immediately but should be considered for future expansion.
Armored Cable
Armored cable, addresses the special needs of outdoor cable that will be exposed to potential damage from equipment, rodents, and other especially harsh attacks.
Armored cable consists of a cable surrounded by a steel or aluminum jacket which is then covered with a polyethylene jacket to protect it from moisture and abrasion. It may be run aerially, installed in ducts, or placed in underground enclosures with special protection from dirt and clay intrusion.
Messenger Cable
When a fiber optic cable must be suspended between two poles or other structures, the strength members alone are not enough to support the weight of the cable. Installers must use a messenger cable, which incorporates a steel or dielectric line known as a messenger to take the weight of the cable. The cable carrying the fiber is attached to the messenger by a thin web and hangs below it, as shown in Figure 1.
Also called figure 8 cable for the appearance of its cross section, messenger cable greatly speeds up installation of aerial fiber cable by eliminating the need to lash a cable to a pre-run messenger line.
Figure 1. Figure 8 cable is used for aerial installations.
Drop Cable
Fiber drop cables for aerial and building installations, designed to run from the distribution point to the subscriber. Drop cable serves as the last link for the FTTx networks of today. Aerial fiber optic drop cable is specifically designed for Fiber-to-the-Subscriber applications. It is a round, all dielectric cable ideally suited for self-supporting drop-type installations as well as in lashed or conduit builds. Flat drop cable is designed for quick installation and ease in handling.
Ribbon Cable
Ribbon cable is a convenient solution to some space and handling problems. The cable contains fiber ribbons, which are actually fibers bonded side by side by Mylar tape in a single tight jacket.
Because the fibers are bonded together so closely, fiber ribbons take up much less space than individually jacketed ones. As a result, the ribbons allow more fibers to be packed into loose tube cables, saving installation time and greatly reducing the required space for installation. As shown in Figure 2, ribbon cables come in two basic arrangements. In the central tube ribbon cable, fiber ribbons are stacked on top of one another inside a loose tube buffer. This type of arrangement can hold several hundred fibers in close quarters. The buffer, strength members, and cable jacket carry any strain while the fiber ribbons float inside the buffer tube.
Figure 2. The central tube ribbon cable (bottom) and the jacketed ribbon cable (top)
The jacketed ribbon cable looks like a regular tight buffer cable, but it is elongated to contain a fiber ribbon. While ribbon fiber provides definite savings in conduit and cabinet space and splicing and connectorizing time, it does require special equipment and training to take advantage of those benefits. Connectors, strippers, and cleavers must all be tailored to the ribbon fiber dimensions, and installers must know how to use the equipment properly. For these reasons, ribbon fiber may not be the best solution in all situations. It should be considered, however, for high-volume installations where the initial equipment and training investment is offset by the time and space savings it provides.
Hybrid Cable
Hybrid cable, as applied to fiber optics, combines multimode and single-mode fibers in one cable. Hybrid cable should not be confused with composite cable, although the terms have been used interchangeably in the past.
Refference Document: Fiber Optics Installer and Technician Guide by Bill Woodward