News & Solutions-Precautions for construction of indoor optical cable and outdoor optical cable
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Precautions for construction of indoor optical cable and outdoor optical cable
Release Date: 2022-05-07

Usually, in the integrated wiring, we will encounter the laying of indoor and outdoor optical cables. The laying of indoor optical cables Indoor optical cables are mainly used in the laying of horizontal subsystems and vertical backbone subsystems. The laying of cables for the horizontal subsystem is very similar to twisted pair, except that due to the lower tensile properties of the cables, more care should be taken when pulling and the radius of curvature is larger. Vertical backbone subsystem optical cables are used to connect equipment rooms to wiring rooms on various floors, and are generally installed in cable shafts or risers. The outdoor optical cable is mainly used for the wiring of building complex subsystems. When implementing the wiring of the building complex subsystem, the pipeline optical cable should be the first choice, and the direct buried optical cable or the overhead optical cable should be used only in the case of unavoidable circumstances.

1. Laying of indoor optical fibers

In order to prevent sagging or slipping, the optical cable must be firmly fixed at the top, bottom and middle of the channel on each floor. Usually, nylon cable ties or steel clips are used for effective fixation. Finally, linoleum plugging materials are also used to block and seal all the grooves and the gaps of the pipe holes through which the optical cables pass through each floor in the building, and fire prevention measures such as plugging fire-proof materials should be taken to achieve the effect of moisture-proof and fire-proof.

When laying the optical cable, an appropriate length should be reserved according to the design requirements. Generally, 5m-10m should be reserved at the equipment end, and it should be appropriately extended if there are special requirements.

2. Laying of outdoor optical fibers

The laying of outdoor optical fibers is divided into the laying of pipeline optical cables and the laying of direct buried optical cables

Laying of pipeline optical cable

1. Clean and test. Before laying the optical cable, the pipe holes should be cleaned and tested one by one. When cleaning, use a special cleaning tool, and use a test stick for test pass inspection after cleaning. The inner diameter of the plastic sub-tube should be 1.5 times the outer diameter of the 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. Lay out the plastic tube. When wearing more than two plastic sub-pipes, if the pipes are of different colors, the ends may not be marked. If the pipes are the same color or no color, they should be marked separately at their ends.

3. Optical cable traction. Generally, the length of one-time pulling of optical cable should be less than 1000m. When this distance is exceeded, segment traction should be adopted or auxiliary traction should be added in the middle position to reduce cable tension and improve construction efficiency. In order to protect the surface of the optical cable from damage during the pulling process, when the optical cable penetrates into the pipe hole, the pipe bend or crosses with other obstacles, protective measures such as guiding device or bell mouth protection pipe should be adopted.

4. Reserve the margin. After the optical cable is laid, the optical cable should be placed on the specified pallet one by one in the manhole or hand hole, and an appropriate margin should be left to prevent the optical cable from being too tight. When the optical cable in the manhole or hand hole needs to be connected, the reserved length should meet the minimum value specified in the table.

5. Joint processing. The optical cable shall not have a joint in the pipe hole in the middle of the pipe. When the optical cable does not have a connector in the manhole, the optical cable is required to be bent and placed on the optical cable support plate for fixing and binding, and must not pass directly in the middle of the manhole, otherwise it will not only affect the construction and maintenance, but also easily lead to damage to the optical cable. When the optical cable has joints, it should be protected by pipes such as snake-shaped hoses or soft plastic pipes, and placed on the pallet to be fixed and bound.

6. Blocking and marking. The outlet end of the pipe hole through which the optical cable is placed should be tightly sealed to prevent moisture or debris from entering the pipe. Optical cables and their splices should have identification marks, and indicate the serial number, type and specification of the optical cable. Antifreeze measures should also be taken in severe cold areas to prevent the optical cable from being damaged by freezing. In case the optical cable may be damaged by collision, insulating plates can be installed on or around it for partition protection.

Laying of direct buried optical cable

1. Buried depth. Since the direct buried optical cable is directly buried under the ground, it must have a certain distance from the ground. With the help of the ground tension, the optical cable is not damaged. At the same time, it should also be ensured that the optical cable is not damaged by freezing.

2. Cleaning and backfilling of optical cable trenches. The bottom of the ditch should be flat and free of debris such as gravel and hard clods that hinder the laying of optical cables. If the trench is stony or semi-stony, 10cm thick fine soil or sand should be laid at the bottom of the ditch and leveled. After the optical cable is laid, 30cm thick fine soil or sand should be backfilled as a protective layer. It is strictly forbidden to mix gravel, bricks, hard soil blocks, etc. into the protective soil layer. The protective layer should be gently stepped on manually.

3. Optical cable laying. When laying optical cables or cables in the same trench, they should be pulled and laid separately at the same time. If it is laid in the same trench as the direct buried cable, the cable should be laid first, and then the optical cable should be laid in parallel at the bottom of the trench. Just like laying optical cables in trenches, they should be laid separately at the same time, and must not cross or overlap at the bottom of the trenches. The optical cable should be laid flat at the bottom of the trench or bent naturally to release the stress of the optical cable. If it is bent or arched, try to lay it flat, but it is absolutely not allowed to use strong methods such as stepping on the foot.

4. Identify. Marks should be set up at the joints, turning points, reserved lengths, or intersections with other pipelines of directly buried optical cables for future maintenance. The sign can either use an autocratic sign, or borrow a permanent building near the optical cable, measure the distance between a certain part of the building and the optical cable, and record it for future reference.

3. Attentions in fiber optic construction

In addition, in the integrated wiring, the reasons that affect the attenuation of optical fiber signals mainly include internal factors and external factors. The attenuation of internal factors is related to the fiber material, which is achieved by purchasing high-quality fiber products. The external factors are related to the construction of optical fiber wiring, because during the construction, the optical fiber is deformed, the coupling loss between the optical fiber and the light source, and the connection loss between the optical fibers are caused, which can be reduced during the construction process. Therefore, it is reminded that you should pay attention to the following when laying optical fibers:

1. The minimum bending radius cannot be exceeded when bending the optical cable.

2. The traction force for laying optical cables should not exceed the maximum laying tension. At the same time, avoid external forces (lateral pressure, impact, bending, twisting, etc.) on the optical fiber.

3. The termination and maintenance of the optical fiber should be performed by strictly trained technicians. When the optical cable is used in the backbone, at least 6-core optical cable should be used in the wiring room of each floor, and 12-core optical cable should be used for advanced applications. This is considered from three aspects: application, backup and expansion. As for the networking mode of optical fiber, it is also very flexible. can be realised:

A, point-to-point: establish a high-speed channel between two computers. The transmission rate is from several Mbps to several hundreds of Mbps, and the distance can be up to 2 km (multimode) to 5 km (single mode).

B. Star network: establish a star network topology through optical fiber network equipment.

C. Ring network: The signal regenerator is connected by optical fiber to form a loop.

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