July 04, 2023

What are precautions for laying low-current engineering optical cables?

Installation of a security cable: An open wiring system places much higher technical requirements on structure of a guy wire than other wiring, which is mainly determined by characteristics of transmission medium. In an open wired system, two types of transmission media are commonly used: twisted pair and optical fiber. Although their material composition and transmission characteristics differ, they all require careful tension when pulling cables. .

What are precautions for laying low-current engineering optical cables?

1. When laying optical cables, following basic requirements must be observed:

l Since core of optical fiber is made of quartz glass, it is very easy to break, so it is strictly not allowed to exceed minimum allowable bending radius during construction. At least 10 times outer diameter of optical fiber when bundled and at least 15 times outer diameter of optical fiber when pulling wire. Secondly, tensile strength of optical fiber is less than that of copper cable, so construction is never allowed to exceed tensile strength (46 N). When an optical fiber is to be turned, its turning radius must be more than 20 times diameter of optical fiber itself.

l When optical fiber passes through a wall or floor, a protective capped plastic tube must be added, and tube must be filled with flame retardant filler. Also, a certain amount of plastic pipes can be laid in advance in building.

l The length of one deployment should not be too long (usually 2 km), and wiring should be carried out from middle to both sides.

l When optical fiber is used in backbone network, at least 6-core optical cables should be used in wiring room on each floor, and 12-core optical cables should be used for extended applications. It's looked at from three perspectives: application, backup, and capacity expansion.

l Before laying cables, check if all grooves and pipes are made and comply with requirements, if laying and position of installed data port is in accordance with project, and determine if there are any omissions.

l Check if pre-laid pipe is smooth and if wire inside pipe is in place, if not, then it should be dealt with first.

l Check pipeline before laying line, clean pipeline and polish nozzle before threading. Remove debris and accumulated water in pipe. If possible, use 0.25 MPa compressed air to blow in talc powder to ensure threading quality. All metal conduit covers and edge guards must be ground without burrs to avoid scratching cables.

l When threading wires into pipe, avoid excessive tension on cable, and pulling force per meter should not exceed 7 kg to protect twisted length of wire pair.

l When laying cables, cables should not be at a dead angle or knotted to ensure good cable performance. When laying cables in a horizontal cable, cables should be straight, avoid damaging cable sheath or stepping on cable if possible.

l In rooms with ceilings, all horizontal cable work must be completed before ceiling is installed; all cables must not be exposed.

l Length of reserved wires: The reserved length at end of wiring room on floor and control room (trunk to ground and up) is 3-5m for copper cables, 7-9m for optical cables, and 0.4m for data points.

l When laying cable, both ends must be marked, and cable marking must be clearly marked. There must be a single marking on both ends of cable, and line marking must be clear and legible. When marking line number, it is necessary to hold beginning of line with left hand and end of line with right, in order to further facilitate confirmation of line number.

l Vertical cable routing: Pull cable from top to bottom. When laying cables, cables must be parallel and not tangled with each other. Cables must not be kinked or knotted.

l The optical cable should be protected as much as possible from being crushed by heavy objects.

l Bonding: Temporary bonding should be done during construction and threading to avoid vertical tension, and then bonding to reduce effect of gravity sag on cable performance. After main is threaded, overall piping is done, and distance between piping should be ≤1.5m. Optical cables must be packed separately. If a bend occurs during tying, it must correspond to a bend radius of at least 10 cm.

l Fill out payment record form: number assigned to backbone optical fiber in record must indicate floor number and serial number.

l After laying optical cable, there must be sufficient length at both ends, and corners and straight sections must be disassembled and cut after confirmation by commander that they meet design requirements.

l After routing cables through wire slot, close slot cover to meet fire, moisture, and rodent protection requirements.

l There are two types of distribution frames: wall-mounted and rack-mounted. According to number of embedded fibers, they can be divided into 24, 48 and 72 ports. There are adapter plates on wiring. frame for mounting screeds. .

l Before an optical fiber enters distribution board, it must be properly bundled. After entering distribution board, it is necessary to reserve a certain amount of spare cables to facilitate installation and maintenance. Spare cables should be wrapped around reels of fiber optic distribution frame.

l Wall-mounted informational wall mounts are usually built-in. In China, standard type 86 wall box is used. The wall box is square, 80X80mm, and 60mm screw hole spacing. The distance between wall information box and wall socket must be more than 20 cm.

l Wall-mounted desktop seat dolshould be coordinated with furniture and tables, and safety of installation site should be considered. The distance between wall information box and wall socket must be more than 20 cm.

l The raised floor is installed in a prefabricated floor box, which can accommodate information wall mounts and power wall mounts.

l Before laying cable, a plate must be prepared indicating serial number, model, specification, card number and cable starting point.

2. Wiring inside cabinet (box)

l Install rack and cabinet according to design and installation diagram, with installation screws tightened.

l Rack and cabinet installation must be aligned with position of incoming line; during installation, it is necessary to adjust level and verticality, and deviation should not exceed 3 mm.

l Install distribution frame according to installation drawing and layout drawing provided by supplier.

l The metal bases of racks, cabinets and switchboards must be grounded.

l Check that cable numbers are correct.

l Before termination, cables in cabinet must be bundled, and bundles must be neat and beautiful. There should be a power reserve of about 1 meter.

l When stripping cable jacket, use a special wire stripping tool, while insulation layer must not peel off, and there must be no disconnection in middle of cable.

l Before termination, switchboard termination table must be prepared and cable termination must be carried out in accordance with termination table.

l Optical cables included in cabinet (box) from site must be pre-checked and numbered.

l Optical cables entering cabinet (box) from platform must be fixed.

l There must be a certain margin for entering optical cables into cabinet (box) from field.

l Optical cables entering cabinet (box) from field should, if possible, not cross each other.

l According to diagram, wiring is correct, connection is strong and contact is good, wiring is neat, beautiful, sign is clear.

3. Optical cable termination technology

l Any cable runs into problem of wrong length, and same goes for optical cables: either it's too long and needs to be cut, or it's too short and needs to be lengthened. At same time, fiber optic cable has a large logarithm when it is transmitted outdoors. When it is connected to central office, cores inside must be connected separately. At this time, optical fiber also needs to be terminated. Therefore, optical cable termination is widely used in various wiring situations.

l This time, to build fiber optic wiring of all-fiber digital integrated operating room, a method is proposed that fabRica directly orders cables and orders ready-made 12-core trunk optical cables of required length according to actual situation on site, and lay them on site, so pipeline capacity configuration must be thought out in advance, before deployment.