CABLE DESIGN

　　There are 2 basic cable designs in fiber optics, loose-tube cable and tight-buffered cable. The loose-tube cable is used in most of the outside plant installations with the tight-buffered cable being primarily used inside buildings.

　　The loose-tube cable will usually have up to 12 fibers per buffer tube with a maximum per cable fiber count of more than 200 fibers. These are modular in design and can be all-dielectric (insulated) or have the option of being armored.

　　LOOSE TUBE CABLE In the loose-tube cable design, color-coded plastic buffer tubes house and protect optical fibers. A gel filling compound impedes water penetration. Excess fiber length (relative to buffer tube length) insulates fibers from stresses of installation and environmental loading. Buffer tubes are stranded around a dielectric or steel central member, which serves as an anti-buckling element.

　　The cable core typically uses aramid yarn as the primary tensile strength member. The outer polyethylene jacket is extruded over the core. If armoring is required, a corrugated steel tape is formed around a single jacketed cable with an additional jacket extruded over the armor.

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