Relevant Problems of Indoor and Outdoor Optical Cable Wiring

Source: CPS Zhongan Network


With the development of science and technology, higher and newer requirements are put forward for optical fibers. The old wiring standards have been tested by practice and are now being revised. In addition to revising the original specifications, some new requirements will be added. It is believed that optical fibers will play a more important role in it. It is not difficult to predict the bright future of optical fiber communication and optical fiber wiring. Next, we will introduce the implementation of indoor and outdoor optical cable wiring related issues.



Often, in general cabling, we will encounter the laying of indoor and outdoor optical cables. The laying of indoor optical cables is mainly applied to the laying of horizontal subsystems and vertical backbone subsystems. Horizontal subsystem cable laying is very similar to twisted pair cable laying, but because the cable's tensile performance is worse, it should be more careful in traction, and the radius of curvature should be larger. Vertical trunk sub-system optical cable is used to connect equipment to each floor wiring, generally installed in the cable shaft or rising room. The outdoor optical cable is mainly used for the wiring of the sub-system of the building complex. In the implementation of sub-system wiring in building complex, pipeline optical cable should be preferred, and buried optical cable or overhead optical cable should be selected only when it is necessary.




Laying of indoor optical fibers



In order to prevent sagging or sliding, the optical cable must be firmly fixed in the channel, bottom and middle of each floor. Usually, nylon straps or steel clips can be used for effective fixation. Finally, the oil flax sealing material is used to block and seal all grooves and voids in the holes of the fiber optic cables in each floor of the building, and fire prevention measures such as plugging fire prevention materials should be taken to achieve the effect of moisture proof and fire prevention.




When laying optical cable, appropriate length should be reserved in accordance with the design requirements. Generally, 5 - 10 m should be reserved at the end of the equipment. If there are special requirements, it should be extended appropriately.



Laying of outdoor optical fibers can be divided into laying of pipeline optical cables and laying of directly buried optical cables.



Laying of Pipeline Optical Cable



1. Clean and try it out. Before laying the optical cable, the holes should be cleaned and tried out step by step. Autocratic cleaning tools should be used when cleaning, and trial-run sticks should be used for test-run inspection after cleaning. The inner diameter of plastic tube should be 1.5 times of the outer diameter of optical cable. When more than two sub-pipes are placed in a cement pipe hole, the equivalent total outer diameter of the sub-pipes should be less than 85% of the inner diameter of the pipe hole.



2. Place plastic pipes on cloth. When more than two plastic tubes are inserted, if the pipes are of different colours, the ends may not be marked. If the pipes have the same or no color, they should be marked separately at the end.



_3. Optical cable traction. The primary traction length of optical cable should generally be less than 1000m. When the distance exceeds this distance, the method of sectional traction or auxiliary traction should be adopted in the middle position to reduce the tension of optical cable and improve the construction efficiency. In order to protect the appearance of optical cables from damage during traction, the protective measures such as guiding device or bell mouth protective pipe should be adopted when the optical cables penetrate the pipe hole, pipe bend or intersect with other obstacles.



_4. Reserved margin. After laying the cable, the cable should be placed in manhole or hand hole one by one on the specified bracket, and appropriate margin should be left to prevent the cable from being too tight. When the cable in the manhole or hand hole needs to be connected, the reserved length shall conform to the minimum specified in the table.



_5. Joint treatment. The optical cable shall not have joints in the holes in the middle of the pipe. When the optical cable has no joint in the manhole, it is required to bend the optical cable and place it on the optical cable bracket to fix and tie it, so that it can not pass through the manhole directly. Otherwise, it will not only affect the construction and maintenance, but also easily lead to the damage of the optical cable. When the cable has joints, snake hose or soft plastic pipe should be used for protection and fixed on the bracket.



_6. Sealing and marking. The outlet end of the pipe hole through which the optical cable is placed should be sealed tightly to prevent moisture or debris from entering the pipe. Fiber optic cables and their connection shall be identified with a number, type and specification of the cable, etc. In cold areas, anti-freezing measures should also be taken to prevent the damage of optical cables caused by freezing. If the cable may be damaged by impact, insulating plates can be installed on or around the cable for partition protection.



Laying of_Direct Buried Optical Cable



_1. Depth of burial. Direct buried optical cable is buried directly in the ground, so it must have a certain distance from the ground. With the help of the ground tension, the optical cable can not be damaged. At the same time, it should be ensured that the optical cable can not be frozen.




_2. Cleaning and backfilling of optical cable trench. The bottom of the trench should be smooth and free of debris and hard soil which hinder the laying of optical cables. If the trench is stony or semi-stony, the bottom of the trench should be paved with 10 cm thick fine soil or sand and copied flat. After laying the cable, the fine soil or sandy soil 30 cm thick should be backfilled as the protective layer. It is strictly forbidden to mix gravel, brick and hard soil into the protective layer. The protective layer should be gently leveled manually.



_3. Optical cable laying. When laying optical cables or cables in the same ditch, they should be pulled and laid separately in the same period. If the cable is laid in the same trench as the directly buried cable, the cable should be laid first, then the optical cable should be laid, and arranged in parallel at the bottom of the trench. Like the trench laying optical cables, they should be laid separately at the same time. They should not be overlapped or overlapped at the bottom of the trench. Optical cables should be laid flat at the bottom of ditches or bended naturally to release the stress of optical cables. If there are bends or arches, they should be laid flat, but they must not be rigid such as foot stepping.



_4. Marking. Signs should be set at the junctions, turning points, reserved lengths or intersections of directly buried optical cables for future maintenance and repair.