OPTICAL FIBRE CABLE CONSRUCTION AND FITTINGS

OPTICAL FIBRE CABLE AND FITTINGS


General


This section of the specification covers optical fibre suitable for incorporation in to the non-metallic underground fibre optic cable.

Type and Uses


 For details of the specified requirements reference shall be made to Appendices.

 DESIGN OF FIBRE OPTIC


Reliability


The overall system design of the fibre optic system shall meet following minimum requirements:

· The product reliability is to be ensured through rigorous quality testing of each product family. Both initial and periodic quality testing is to be performed to assure the cable performance and durability in the field environment.

· Increase in optical system transmission attenuation due to accumulated ageing and other effects at the end of five years not more than 0.05 dB/km.

 Optical Fibre


General

Optical fibres shall be single mode fibre. The fibres shall be coded for ready identification at each end. Single mode fibres shall conform to CCITT G652 or to IEC 793-B1 and Appendix 8.A2.

The optical fibre coating material shall be mechanically strippable. The optical fibres shall be capable of being joined by fusion splicing techniques.

The opticla fibres shall not be subjected to any critical stresses when the cable is at its maximum system loading reference Appendix.

The fibre optic cable shall be circular in cross section and shall be designed so that any cable strain is not directly imported on the optical fibres. The cables shall not include any metallic components to prevent high induced voltage when used by the side of power cable.

Constructional Features of Optical Fibre Cable


Optical fibres shall be single mode constructional features of the optical fibre cable have to be in line with the date given below:

·         Optical fibre               
·         Loose buffer tube   
·         Cable                         
·         Colour code              

Required drawings for construction of the optical fibre of the optical fibre construction of loose buffer tube constructional feature of the optical fibre cable as a whole and specifications of the optical fibre are to be attached with the offer of the Bidders separately and standard of specifications are to be mentioned in the offer of the bidder. Detailed date about similar projects (as a minimum three (3)) of compatible volume have to be provided with the offer. After finalisation of the drum lengths the contractor / supplier shall submit calculations for the expected overall attenuation and dispersion. This is a Hold point. This will be compared with the actual values measured after a completion of the installation.

Characteristic


Details on optical fibres please see:

· Optical properties of the optical fibre.

Sheath Printing


The following marks shall be printed on the cable sheath in one meter intervals:

·               Symbol of FOC
·               Manufacturer Name
·               Year of manufacturer
·               Length marking
·               Warning tape shall be used as per standard.


The box shall be supplied complete with internal spice cassettes tok accommodate the required number of splices. Glands shall be fitted to accommodate the underground fibre poetic cable.

Required drawings and specifications are to be supplied along with the document and standard of specification is to be referred to.


PACKING DRUM


The cable will be delivered in the length required on a wooden durm.

Cable end


The both end of the cable shall be fitted with a suitable cap to protect the FOC from the penetration of water or dirt.




OPTICAL JOINT BOXES


General

Optical joint boxes shall be provided to protect the splice joints when individual lengths of fibre optic cables are jointed. The optical joint Boxes shall protect the splice from both mechanical and environmental damage.

Characteristics


The joint boxes shall consist of high impact plastic ABS box to IEC 529 IP54.

The external housing shall be designed so that rainwater is directed away from the door, and there shall be no water ingress when the door is opened.


The door of the box shall be fitted with captive hinges and shall be fastened shut by screw fixings.

The bottom of the box shall be fitted with a gland plate with four entry points suitable for a certain number of different FOC diameters. The joint boxes shall be supplied compete with all fittings to satire and seal the cable in the gland plates or blank the unused spigots. Cable cleats to secttre the fibre optic underground cable shall be fitted inside the box. The cleats shall not have a detrimental effect on the performance of the optical fibres when tightened to the recommended torque.

      The top and bottom of the joint box shall be vented and the vents provided with vermin shields.

The box shall be supplied complete with internal splice cassettes to accommodate the required number of splices. Glands shall be fitted to accommodate the underground fibre optic cable.

Required drawings and specifications are to be supplied along with the document and standard of specification is to be referred to.

FIBER OPTIC TERMINATION ENCLOSURE


At both end of a FOC line fibre optic termination equipment (FOTE) is to be installed where the FOC shall be terminated spare length and pigtails are safely fixed. The FOTE should provide easy access to the FOC for maintenance and operating purposes. The interior of the FOTE has to contain cable trays to allow safety store of fibres and splices in accordance with the FOC specification.

The drawing and specifications of the FOTE are to be supplied with the offer and standard specification is to be referred to. The enclosure shall perform the following functions:

·FOTE shall support organise and protect the optical fibres and the fibre splices whilst ensuring that the optical fibre minimum bending radius is not exceeded.

· The splice tray shall not have any sharp edges or protrusions that may damage the optical fibre cable.

·  FOTE shall provide entry for FOC up to 48 fibres

· Number tags for tube and fibre identification are to be included.

· FOTE shall provide mounting positions for the bulkhead FC/PC type connectors on  
  which the cable will be terminated.

· FOTE shall allow patching of fibres

· FOTE shall consist of two (2) separate, lockable compartments one to connect the FOC with pigtails to the couplings and store the spare length of the FOC/ pigtails accurately and a second compartment which provide access to the other site of the coupling only.
This type of enclosure shall be mounted on the wall at a conveniently accessible height.

 FIBER OPTIC PIGTAILS

General

Where a termination enclosure is installed all fibres of all cables are to be terminated on pigtails with a minimum length of 1m.

The pigtail shall be a kevlar® (or aramide) reinforced and plastic coated optical fibre conforming to ITU-T Recommendation G.652. For terminating and connecting the FOC FC/PC type connectors shall be provided. The connector shall be inserted on the cable side of the bulkhead (feed through) connector in the termination enclosure.

All connectors shall be supplied with a removable cap to be protected against moisture and dust ingress when not connected to a coupling.

Required drawing and specifications are to be supplied with the offer and standard of speciation is to be mentioned.

PROTECTIVE TREATMENT

Optical Fibre Cable


Where two layers of wire strands are provided over the optical sub-unit, the external surface of the optical sub-unit and the inner strand fayer shall be greased, using approved conductor grease.

Ingress of moisture
The cable shall be capped before shipment to prevent the ingress of water.

 INSTALLATION


 General

The manufacturer of the optical fibre cable will be responsible for the supervision of installation by the Contractor to ensure that overall system reliability requirements are met. To ensure that this is undertaken, the manufacturer will provide the services of a suitably qualified/experienced installation supervisor, who shall supervise the installation of the works and shall advise the Engineer and contractor in matters of methods procedures and precautions to be followed and will be responsible for all matters pertaining to the quality of the installation. The manufacturer’s installation supervisor shall make at least four visits of 2(two) weeks each during progress of optical fibre cable installation work for the purpose.

The contractor shall provide the Engineer with a method statement giving sequential details of the stripping procedure and the optical fibre jointing (splicing) procedure. The method statement shall take full cognizance of the manufacturer’s installation instructions. The underground optical fibre cable shall be installed through a HKPE duct throughout the length of the cable. The permissible bending radius of the FOC has to be considered in design of the cable route. The HDPE duct has to be sealed on end to avoid animals e.g. rates cannot get in and eat the FOC.

The cable should be installed at least 6 inch below the level of power cable following the drawing attached herewith.

The overall attenuation of the installed cable shall not exceed that calculated using the attenuation and splice loss values specified in Appendix .

The contractor shall give the Engineer the requisite period of notice prior to commencing the tests. This is a Notification point. Details of the test results shall be submitted to the Engineer.

The manufacturer of the FOC is requested to co-operate with the fibre optic terminal equipment manufacturer (if this is under a separate contract) and shall supply all technical data requested.

The manufacturer shall be submitted to the Engineer for acceptance with the requisite period prior to optical fibre jointing commences. This Hold Point.

The following tests shall be undertaken by the contractor.
·Prior to installation the fibre optic cable shall be tested with an OTDR on each             fibre to ensure that no physical damage has occurred to the fibre during, delivery and shall be compared with the results prior to dispatch.

·After installation the above test shall be repeated to ensure that no damage has occurred to the fibre during installation.

·An end to end attenuation measurement shall be taken in each direction on each fibre using an optical source and optical meter.

The overall attenuation of the installed cable shall not exceed that calculated using the attenuation and splice loss values specified in Appendix 8.A2. The tests records have to be submitted to the Engineer for approval.

Workmanship

The contractor shall ensure that the fibre optic cables are not strained or damaged either mechanically or optically during layin gout and paying out of cable and jointing. If necessary the contractor shall demonstrate the suitability of his proposed method, including the choice of running blocks prior to the commencement of laying out and paying out operations.

Optical fibre joints

Optical fibre joints between non-metallic underground fibre optic cables shall be housed in optical joint boxes.


          Construction of the optical fiber

Item
Specification

Fiber Type
Matched Clad type single mode ITU-T optical fiber The    optical   fiber   are   compliance   with recommendation G.652.B
Core
Material
Doped silica

Cladding
Material
Silica

Diameter
125 + 1 µm

Primary Coating
Inner layer
Material
UV curable acrylate

Outer layer
Material
UV curable acrylate

Diameter
245 ± 10 µm

Core / cladding concentricity €
error
Max. 0.8 µm

Cladding non-circularity
Max. 1 %

Mode field diameter
9.0 µm ± 0.5 urn at 1310 nm

Identification
Color coating

Proof test level
Equivalent to 1% strain, 1 sec.


              Construction of loose buffer tube

Item
Specification
Optical fiber
Spec.
The same as Table 1
Fiber/Tube
Max. 6
Filling
Material
Thixotropic Jelly Compound
Tube
Material
PBT or equivalent with color coding
Nom. Outer Dia. (mm)
2.5
Color Code
Table 4
          
            



 Construction of cable

Item
Specification
Fiber
Number
24
Loose buffer tube
Spec.
The same as Table 2.

Fiber/tube
6

Number
4
Central strength member
Material
FRP (Fiber reinforced with plastic) rod

Dia. (mm)
2.0±0.1
Filler
Material
Plastic rod, colored natural

Dia. (mm)
2.5±0.1

Number
1
Binder
Material
Nylon Yarn(s)
Flooding Compound
Material
Water Resistant Compound
Strength Element
Material
Aramid Yarn(s)
Ripcord 1 Inner sheath
Material Material
Plastic thread High Density Polyethylene, colored black

Thickness (mm)
1.0 ± 0.15
Ripcord 2
Material
Aramid Thread
Armor Flooding
Material
Water Resistant Compound
Outer Sheath
Material Thickness (mm)
High Density Polyethylene, colored black 1.310.2
Nylon Sheath
Material
Polyamide, colored black

Thickness (mm)
0.7±0.2
Cable dimension
Approx. (mm)
16
Cable weight '
Approx. (kg/km)
240
Structure
Fig. 4


              Color code of Fibre Optic Cable


         (1) Color code for the fiber in a tube


  Fiber No.
Color of fiber
1
Blue
2
Orange
3
Green
4
Brown
5
Grey
6
White

           (2)  Color code for the tube


   Tube No.
Color of tube
1
Blue
2
Orange
3
Green
4
Brown
5
Grey
6
White


                Mechanical Properties of Cable




Item
Specification
Maximum tensile strength
2700 N
Bending radius of the cable
  • at no load
  • at half max. design tensile load
  • at max. design tensile load
Min. 10D mm Min. 20D
mm (D : Overall cable diameter (mm))
Temperature range
Operation Installation
-10o to 70T –
10o to 70oC

Comments

  1. I have just installed iStripper, so I can have the best virtual strippers on my taskbar.

    ReplyDelete

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