According to the distribution of users in the community within the construction area, after a detailed survey of the roads, buildings and the construction routes of various bearer communication facilities in the community, according to the above user optical cable design principles, select the location of the telecommunication room and optical cable junction box and determine the wiring. Users covered by the district; determine the construction route, construction layout, construction capacity of the user's optical cable, and the location of the optical cable in the building and the way to enter the house.
Weak current engineering
FTTH engineering construction requirements
1. ODF optical distribution frame installation
(1) The installation position and orientation of the ODF frame should meet the design requirements.
(2) The vertical deviation of the ODF frame installation should not be greater than 3mm.
(3) The adjacent racks of the ODF frame should be close together, and the machine surfaces in the column should be flush.
(4) The model of pigtail and adapter configured by ODF is SC model.
(5) The optical fiber connecting lines should be arranged neatly, and the cables should be routed separately in the rack and between the racks.
(6) The static radius of curvature of the optical fiber connection line should not be less than 30mm.
(7) When installing ODF, please refer to the installation manual and operate in strict accordance with the construction specifications. The installation serial numbers of adapters and fiber optic cable pigtails are shown in the drawings.
2. Optical cable is terminated
(1) The optical cable is terminated in the cabinet and the household wiring box for connection with other equipment (if the pre-terminated optical cable is used in the household wiring box, it does not need to be terminated). A safe location should be chosen when the optical cable enters the telecommunication room and the equipment room. When in a position vulnerable to external damage, protective measures should be taken.
(2) Indoor optical cables should be tied and fixed and arranged neatly when they pass through the cabling racks, turning points, and other positions. The parts of the upper and lower walkways or climbing walls should be padded with rubber hoses to avoid lateral pressure on the optical cables. Its length and the radius of curvature of the optical cable should meet the design requirements.
(3) The optical cable should be terminated in the cabinet and bound and fixed in the cabinet. The metal components in the optical cable should be in good contact with the protective grounding device of the cabinet. (Protection area and mine protection area)
(4) The end of the optical fiber should be spliced with the pigtail according to the fiber sequence, and the corresponding relationship between the fiber core and the user should be marked in the cabinet.
(5) When the optical cable is terminated, there should be a pigtail and optical jumper storage and protection device in the rack, and the optical fiber should be terminated by hot-melt technology. For single-core optical fiber thermal fusion splicing, the average bidirectional attenuation should be less than or equal to 0.06dB.
3. Laying of pipeline sub-pipes
In this project, when laying plastic sub-pipes in a 90mm diameter plastic pipe, three sub-pipes shall be laid at one time. The sub-pipe shall not be laid across the hand hole, and the sub-pipe shall not have joints in the pipeline. The extension length of the sub-pipe in the hand hole is generally 100-200mm. Pipe holes and sub-pipe holes that are not used in this phase of the project should be blocked in time.
4. Pipeline cable laying
(1) Before construction, it should be checked whether the length, number of cores and specifications of the optical cable meet the design requirements.
(2) According to the requirements of the design documents, select the position of the optical cable to occupy the hole. If the design is not determined, the tube hole should be selected according to the principle of first up and down, first on both sides and then in the middle.
(3) When laying the optical cable, there must be a special person instructed. Each hand hole should be guarded, obey the command, and act according to the command to prevent the occurrence of small circles and unsafe factors.
(4) When guiding and releasing the optical cable, corresponding anti-wear measures should be taken for the opening ring of the optical cable to prevent damage to the optical cable.
(5) After laying, the optical cable should be straight, no twist, no obvious scratches and damage, and the length of the joint should meet the design requirements.
(6) After the optical cable is laid, it should be fixed in the hand hole. The optical cable should not be bent within 15cm of the outlet hole, and other parts should be fixed against the wall of the hand hole. The radius of curvature of the fixed optical cable must be greater than 15 times the diameter of the optical cable.
(7) The optical cable must be listed in each hand hole. The listing should be hung in an obvious position, and the content of the listing should reflect the program and direction of the optical cable.
(8) After the cables introduced into the building are laid, blocking measures should be taken at both ends of the entry pipes.
5. Laying of optical cables in the building
(1) Before construction, the route should be carefully surveyed and calculated to determine the length of the cable. The speed of insertion and release should be controlled, and special personnel should be kept on duty at the optical cable reel to prevent the optical cable from being entangled and knotted.
(2) The optical cable must be laid manually. When laying in the dark pipe and channel, it should be laid out in sections, and the length of one-time traction should not exceed 20 meters.
(3) The entrance optical cable needs to be guarded at the exposed places where the bends or hidden pipes and channels are connected to prevent the optical cables from being twisted, knotted and scratched.
(4) When laying the optical cable at home, the traction force should be less than 80% of the short-term force limit of the optical cable.
(5) Inorganic lubricant or special lubricating oil should be properly applied to reduce the friction coefficient when the home optical cable is put in the dark pipe.
(6) When using the traction wire in the dark pipe to lay the home optical cable, the traction wire should be connected with the strengthening member of the home optical cable.
(7) When the household optical cable is laid vertically along the channel and bridge, it should be fixed at the upper end of the optical cable and at every interval of 1.5m, and the fixing should be properly tight; Fix at ~10m.
(8) The reserved length of indoor optical cable should meet the following requirements.
1) The reserved length of the optical cable at the wiring cabinet (rack) is 3.0 m ~ 5.0 m;
2) The length of the optical fiber reserved at the optical distribution box on the floor is 1.0 m ~ 1.5 m.
3) When the optical cable is terminated in the household wiring box, the reserved length should not be less than 500mm.
4) When the fiber core of the user optical cable is not terminated in the user side distribution module, the reserved length of the optical cable should be reserved.
6. Optical cable connection
(1) Special tools should be used to cut the cable and strip the outer sheath of the cable to avoid damage to the optical fiber or the insulation layer of the core wire.
(2) Check the cable end and fiber (line) sequence before connecting, and the fiber (line) sequence should not be wrongly connected after connecting.
(3) The cable end and fiber (line) sequence should be permanently marked.
7. Installation of optical cable joint box
(1) The strength of the optical cable must be firmly fixed in the splice box, and the metal members should be in an electrically disconnected state at the splice.
(2) When the optical fiber is reserved in the splice box, it should be ensured that its radius of curvature is not less than 30 mm, and the winding direction should be the same, without extrusion and loosening.
(3) The joint box should maintain good water tightness and air tightness after sealing.
(4) Protection and fixing measures should be taken in the hand hole of the pipe optical cable joint box, and the remaining length of the optical cable after the connection should be placed in the hand hole according to the design requirements and fixed neatly.
8. Installation of optical fiber distribution box in the building
(1) After the user optical cable enters the building, the capacity of the optical fiber distribution point on the floor is reasonably allocated according to the number of users covered. In order to facilitate line maintenance and user management, the number of users accommodated by the optical fiber distribution box on the floor should not be too large. Usually, an optical fiber distribution point on a floor can accommodate 12 to 48 more optical fiber users. When the installation conditions allow (such as in the weak current shaft), the number of users accommodated by the optical fiber distribution point on the floor can be appropriately increased.
(2) The user optical cable and the household butterfly optical cable are connected by fusion splicing.
(3) When laying the butterfly optical cable from the optical fiber distribution box on the floor to the floor where the resident is located, it should be protected by a pipe.
(4) Box installation height: The distance between the bottom edge of the concealed box and the ground should not be less than 1.5m, and the distance between the bottom edge of the exposed box should be more than 1.8m.
9. Installation of optical cable junction box
The installation position of the optical cable transfer box should meet the following requirements.
(1) The junction or branch of the cable;
(2) In the green belt beside the sidewalk, in the corner of the courtyard, and in the leeward;
(3) A location that is less susceptible to external damage, relatively safe and concealed, and does not affect the aesthetics of the environment;
(4) The position close to the human (hand) hole is convenient for cable entry and exit, and is convenient for construction and maintenance;
(5) Avoid places such as high temperature, high pressure, severe electromagnetic interference, severe corrosion, flammable and explosive, and low-lying places;
(6) Avoid places with vibration such as air-conditioning outdoor units and ventilator rooms;
(7) Avoid the normal passage of pedestrians and vehicles.
10. Installation of the base of the optical cable transfer box
The installation base of the optical cable junction box shall meet the following requirements:
(1) It is advisable to use concrete cast-in-place base and pre-embed PVC pipes.
(2) The concrete poured at the base should be cement with a strength grade of 32.5MPa and above.
(3) The height of the base should not be less than 300mm.
(4) The length and width of the base should be greater than the length and width of the bottom of the box, and the length x width should not be less than 800mmX 400mm.
(5)The box should be fixed to the cement base with M12 expansion bolts.
