Planning of Works and Contractor’s Responsibility

Contractor’s Responsibility on Planning of Works to Execute A Underground Cable Project

Within 30 days after acceptance of the Tender, the Contractor shall prepare, in an agreed form, a detailed Manufacture, Delivery and Erection Program Chart for the complete Contract Works, and shall submit the chart to the Employer for approval.

The Manufacture, Delivery and Erection Program Chart shall indicate for each major item of the Contract the various phases of work from the commencement of the Contract to its completion, e.g., design, ordering of materials, manufacture, delivery, installation and commissioning. The program shall include a fully comprehensive drawings production program which shall demonstrate the Contractors intended issue dates for approval.

These presentations shall be in bar chart and precedence critical path analysis format.

The program shall indicate percentage completion points of the various phases which can form the basis of progress reporting.

A cash-flow forecast of the estimated monthly invoice values shall be included in the program. This forecast shall take into account the terms of payment and indicate down-payments, the release of retention’s, etc. Figures may be rounded to the nearest thousands of the appropriate currency.

The Contractor shall indicate in the program the number, grade and discipline of supervisory and managerial site staff proposed throughout the site construction periods. If specialist erection and commissioning staff are to be employed by the Contractor details of the number, discipline and duration of the visit of these staff are to be indicated in the program. 

The provision of this information will not form any contractual limit on the number of staff to be provided by the Contractor to ensure the timely completion of the contract. Should any incident occur which, in the opinion of the Contractor will result in an over-run of any section of the Works this shall be indicated in the program and brought to the Employers attention.

If at any time during the execution of the Contract, it is found necessary to modify the approved Manufacture, Delivery and Erection program Chart, the Contractor shall inform the Employer and submit a modified chart for his approval. 

The submission, and subsequent approval, of a modified Manufacture, Delivery and Erection program Chart shall not necessarily obviate or diminish the Contractor’s responsibilities and liabilities under the Contract. The Chart shall be updated at monthly intervals and submitted to the Employer no later than the middle of each calendar month.

OPTICAL FIBRE CABLE CONSRUCTION AND FITTINGS

What is the Optical Fiber Cable and its Fittings?

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

Design Guide of a Fiber Cable

Fig: Fiber Optic Cable Sectional Diagram 

The overall system design of the fibre optic system shall meet the 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.

 What Would be Optical Fibre for Cable Construction?

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 optical 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 the power cable.

What Would be Major Constructional Features of Optical Fiber 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 the construction 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 data 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 the completion of the installation.

Characteristic of FOC

For details on optical fibres please see

Optical properties of the optical fibre.

Sheath Printing of Fibre-optic Cable

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

1. Symbol of FOC
2. Manufacturer Name
3. Year of manufacturer
4. Length marking
5. Warning tape shall be used as per standard.

The box shall be supplied complete with internal spice cassettes to 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 the standard of the specification is to be referred to.

What Would Be the Packing Drum?

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

Cable end Identification

Both ends of the cable shall be fitted with a suitable cap to protect the FOC from the penetration of water or dirt.

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.

What Would be the Characteristics of Fiber Optic Cable Joint Boxes?

The joint boxes shall consist of a 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 complete with all fittings to satire and seal the cable in the gland plates or blank the unused spigots. 

Cable cleats to settle 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 the standard of the specification are to be referred to.

What Would be Fiber Optic Enclosure Feature?

At both ends 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 safe 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.

What is the Fiber Optic Cable Pigtails?

Where a termination enclosure has been 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 aramid) 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 drawings and specifications are to be supplied with the offer and the standard of speciation is to be mentioned.

Protective Treatment of 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 flayer shall be greased, using approved conductor grease.

Ingress of moisture

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

Optical Fibre Cable Installation Guides

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 the 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 an HKPE duct throughout the length of the cable. 

The permissible bending radius of the FOC has to be considered in the 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 inches below the level of the 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. 

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.

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.

What Would be the Optical fibre joints Feature?

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

 Construction of the optical fibre

Item			Specification
Fibre Type			Matched Clad type single-mode ITU-T optical fibre The    optical fibre 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 colour coding
	Nom. Outer Dia. (mm)	2.5
	Colour 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, coloured 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, coloured 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, coloured black 1.310.2
Nylon Sheath	Material	Polyamide, coloured black
	Thickness (mm)	0.7±0.2
Cable dimension	Approx. (mm)	16
Cable weight '	Approx. (kg/km)	240
Structure		Fig. 4

Colour code of Fibre Optic Cable

(1) Color code for the fiber in a tube

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

           

(2)  Color code for the tube

Tube No.	Colour 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