OUTSIDE PLANT
OUTSIDE PLANTOutside Plant
Outside plant is the network of cables, poles, conduit, feeder cable, distribution cable, terminals, aerial and drop wire, and fiber optics that interconnects CO's and connects from the local CO to the home or customer. The local loop or last mile is the link between the CO and the customer. The local loop is mainly made up of twisted-pair copper wire. Twisted-pair cables are classified by the wire gauge and the number of pairs within the sheath. The sizes vary from 1 pair to 3,600 pair. Wire gauges 19, 22, 24, 26 are used in the loop plant. The cost of the wire determines the use of the smallest wire possible with the best results. In other words smaller wire is used close to the CO and courser grade wire is used farther away from the CO to reduce loop resistance. Over the year the local loop has not changed much but there have been improvements in insulation, cable sheaths, splicing. Most of the outside plant that was aerial has been converted to underground which reduces damage. The connection of CO's have changed dramatically by drunk routes being constructed in underground conduits about ever 6,000 feet. Copper wires can be changed to fiber optics, the material is unlimited, bandwidth provides greater performance, and does not corrode like copper. LEC's don't consider protection equipment and range extension as part of an outside plant.
Local loops are routed from the customer to the CO over twisted-pair cable. The twisted pair could be either aerial cable which is supported by poles. Aerial cable is being discontinued because of its vulnerability to damage. Aerial cable needs external strength for tension relief on the conductors. Direct burial is placed in the ground without a conduit. This method is ideal for rural areas because it is less expensive than conduit. LEC's can place several cables right after each other or where future additions may be needed, or they can place empty conduit to avoid a costly expansion in the future. The manholes are located at the maximum length cable can be physically handled at 6,000 foot intervals to house T-carriers and load coils.
The cable sheath that covers the cable is a highly durable plastic which may be polyethylene and polyvinyl chloride. Cable sheaths guard the cables from lightning, moisture, corrosion, rodents, and birds. In under water cases the wires are the sheath material, jute, and steel armor. Other than the sheath materials, metallic tape is grounded to each end to shield the cable from induction. The twisting of the cables is to preserve...
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