FTTH engineering construction specifications and requirements

This article mainly introduces the matters needing attention in FTTH optical cable laying and related equipment installation requirements.

1. Optical cable routing

Routing retest should be carried out before laying optical cables. The routing and laying method shall be based on the construction drawing design. Necessary routing changes can be proposed by supervisors and construction personnel, and confirmed with the consent of the construction unit; for large routing changes over 500m, the design unit should go to the site to negotiate with the supervisor and the construction unit, and the construction unit approves and fills in the "Engineering Design Change Form". 

 

Second, the laying of optical cables

2.1 The laying type, direction and route of the optical cable should comply with the design documents, and should not cross with the power cable.

 

2.2 The optical cable should be laid in a straight line, without obvious twists and crosses; the optical cable in the channel must be firmly bound, the appearance is straight and neat, the tightness is moderate, and the binding spacing should be uniform and should not be greater than 1.5m;

 

2.3 The optical cables in the frame should be laid in a straight line, the outlet position should be accurate, the reserved arc length should be consistent, and appropriate binding should be made.

2.4 Each fiber optic cable should have a unified mark on the inlet hole and both ends of the ODF. The mark should indicate the connection position of the two ends of the fiber optic cable and meet the requirements of resource management for the fiber optic cable marking. Label writing should be clear, correct and correct. Labels should be printed plastic for easy maintenance.

 

2.5 The optical cable laying process must meet the requirements of YD5137-2005 "Code for Design of Local Communication Line Engineering" and YD5121-2010 "Code for Acceptance of Communication Line Engineering".

 

2.6 The overlapping and reserved length of the distribution plate, laying and installation of the optical cable shall conform to the reserved length of the optical cable at the joint, and the reserved length is generally 5~10m.

 

2.7 Laying wall optical cables should meet the following requirements: the height from the ground should not be less than 3m, and steel strands should be used to hang across neighborhoods, courtyard passages, etc.

 

2.8 When laying the hanging wire wall optical cable, the hanging wire type used for the hanging wire wall optical cable should meet the design requirements. The distance between the wall supports should be 8-10m, and the distance between the terminal fixture and the first intermediate support should not be greater than 5m.

 

2.9 When laying the nail-fixed wall optical cable, the cable must be fixed with wire clips on the outer wall; the nailing screws must be on the same side of the optical cable, and the spacing is uniform and 400mm is appropriate.

 

2.10 When laying pipeline optical cables, the holes for laying pipeline optical cables should meet the design requirements; the optical cables after laying should have no twist, no cross, no obvious scratches and damage; no bending treatment is allowed within 150mm of the cable outlet hole; The overlapped length reserved for laying the side optical cables should meet the design requirements. After the connection is completed, the excess length of the optical cables should be placed in the manhole and fixed neatly; the pipe optical cable should be reserved for the middle manhole according to the access needs, and the length is 8m-10m; An optical cable identification mark shall be installed on the optical cable in each manhole.

 

ZR Cable laying

3. Line protection

 

1. The newly added cable must be protected by a special warning sleeve.

 

2. When the hanging overhead suspension wire crosses the power line, it should generally pass under the power line, and the overhead suspension wire crossing the power line should be covered with a power protection tube. The distance between the suspension wire and the power line shall meet the requirements of the design and acceptance specifications.

 

3. Fire protection measures should be taken when the optical cable inevitably crosses adjacent buildings and facilities with fire hazards.

 

Fourth, the installation of optical cable junction box and distribution equipment

(1) Installation of optical cable junction box

1. The installation position and fixed type of optical cables, pigtails, jumpers and adapters in the optical delivery box should meet the design requirements and conform to the product description of the optical delivery box.

 

2. The assembly parts of the light delivery box should be complete, the connector row should be undamaged, the terminals should be firm, the braided ends should be fixed in the box, and the number-checking test and insulation test should be carried out, and the paint surface should be intact.

 

3. The optical cable entry boxes should be neatly arranged, and the bends should meet the requirements of the radius of curvature. The lacquer (print) of the number of the delivery box, the cable number, and the fiber (line) sequence should meet the design requirements.

 

4. The jumpers (fibers) in the transfer box should be arranged reasonably and neatly, without joints and without affecting the opening of the module bracket.

 

5. The installation of the wall optical cable junction box should be solid and firm, and the height of the bottom of the junction box from the ground should not be less than 150mm.

 

6. The installation position, installation height, moisture-proof measures, etc. of the floor-standing optical cable junction box should meet the design requirements. The installation of the box must be firm, safe and reliable, and the vertical deviation of the box should be no more than 3mm.

 

7. The ground wire of the handover equipment must be set separately, and the grounding resistance of the ground wire should meet the specification requirements (the grounding resistance of the ground wire of the handover box should not be greater than 10Ω).

 

(2) Installation of branch equipment

1. The installation method, location and model of the branching equipment should meet the design requirements.

 

2. When the junction box is installed on the outdoor wall, the lower end of the box should be 2.8m~3.2m away from the ground, and the installation of the indoor junction box should meet the design requirements.

 

3. After the branching equipment is installed, its serial number should be written on the surface of the branching equipment, and the font should be correct and uniform in size.

 

4. The installation of the wall-mounted junction box should be firm, reasonable and moisture-proof.

 

5. The cables entering and leaving the box should be clearly marked;

 

5. Construction of leather cable

(1) Requirements for laying optical fiber cables inside buildings

 

1. Before laying, you must thoroughly understand the structure of the building and the routing of the wiring. Accurately grasp the cabling position;

 

2. Determine the location and layout of the existing cables, and use the original routing as much as possible.

 

3. The reserved length of both ends of the leather cable should be uniform, not less than 0.5m, not more than 2m and meet the process requirements.

 

4. When laying the fiber optic cable, the turns should be minimized. When it is unavoidable, the turning point should be even and smooth, and the radius of curvature should meet: ① The bending radius of the fiber optic cable should not be less than 40mm during the laying process; ② The back skin should be fixed. The bending radius of the cable should not be less than 15mm;

 

5. The two ends of the leather cable should have a unified mark, and the mark should indicate the connection position of the two ends. Label writing should be clear, correct and correct.

 

6. The indoor wiring of the leather cable should be installed in the dark pipe, ceiling and wall as far as possible.

 

7. The leather cable should strictly meet the requirements of "fireproof, anti-rat and anti-extrusion".

 

(2) Laying of the leather cable in the cable groove

1. When installing wire ducts or PVC pipes, first calculate the number of leather-wire optical cables to be laid in the wire ducts or PVC pipes. If it exceeds 60%, the utilization rate of the pipe diameter of the elbow should not exceed 50%.

 

2. When using PVC pipe for wall laying, select the appropriate part of the wall to determine the routing direction of the cable, and keep the cable horizontal and vertical after the nailing is completed; when nailing, the distance should be evenly 50cm.

 

3. The bending radius of the leather cable should not be less than 40mm in the duct or the trough. When laying the duct or the trough, the two ends of the pipeline should be slightly inclined downward to prevent the long-term accumulation of water in the tube and the performance of the optical cable.

 

(3) How to enter the home of the leather cable in various scenarios

4. The leather cable adopts the method of opening the wall to enter the home: choose a suitable entry location, and use a Φ8mm electric hammer to make a hole through the wall on the user wall. The opening standard is from the user's indoor to the user's outdoor. The opening direction is inclined downward at an angle of 30 degrees to prevent rainwater from pouring into the user's room.

 

5. If the optical fiber cable enters the home through the wall hole or air conditioning hole: it is necessary to install wall bushings on the inside and outside of the wall hole or air conditioning hole. The leather cable is put into the household through the wall casing. The entrance optical cable must leave a "drip bend" at the entrance of the wall.

 

6. After the sheathed optical cable is finished, it is necessary to fill and seal the gap of the hole with plugging and filling glue. Blocking should be flat and firm.

 

7. The wall corrugated pipe protects the optical cable from entering the house, and the wall hole of the outer wall is appropriately opened. After the corrugated pipe is embedded in the wall hole, it is filled and sealed with sealing and filling glue. The opening of the bellows shall not be exposed outside the wall hole.

 

6. Connection and encapsulation of optical cable

1. The optical cable program, fiber sequence, end type, reserved length of the optical cable at both ends, binding and fixing, and the installation position of the splice box should meet the design requirements.

 

2. The content of optical cable connection should include: optical fiber connection; installation of copper wire, metal sheath and reinforcing core; measurement of joint attenuation.

 

3. The average attenuation of optical fiber is not more than 0.08dB/piece when splicing, and the average attenuation is not more than 0.5dB/piece during cold splicing.

 

4.The splicing method of the optical fiber is determined according to the type of optical cable used. The conventional optical cable adopts the thermal fusion splicing method. When using the household optical cable, the user end should use fusion splicing or mechanical splicing.