METHOD STATEMENT
1.1
Method Statement / Work Procedure (General)

Review the cable route drawings, R-O-W drawings, digging permit, and inspect the
cable route from end to end.

Decide locating where cable drums shall be unloaded at site, keeping in view the
actual cable lengths on drums.

Decide locations of cable joints. Avoid street intersections. Joints should preferably
be made not closer than 10 meters from edge of any street intersections.

Obtain necessary permissions from the traffic police for the work schedule, warning
and lights and design of detours.

Keep ready the necessary number of night warning lamps, stands, wooden/steel
bridges for maintaining pedestrian

Arrange necessary manpower keeping in view the work schedule and expiry date
of digging permit
1.1.2
Trench Excavation

The exact location of each trench on Site shall be as per NG-approved IFC
drawings. Trenches shall be kept as straight as possible and each trench shall be
excavated to approved formation and dimensions and shall have vertical sides
which shall be timbered or otherwise secured where necessary so as to avoid
subsidence and damage.

The bottom of each trench shall be firm and of smooth contour. Reasonable
precautions shall be taken to prevent damage to the highway or ground surface from
a slip or breaking away of the sides of the trench.

The trench excavation and filling in shall be so executed that all walls, roads,
sewers, drains, pipes, cables, structures, places and things shall be reasonably
secure against risk of subsidence or injury and shall be carried out to the satisfaction
of the authorities concerned. Should however damage happens to existing services
or utilities, any necessary repair must be arranged and paid for to make good the
damages.

Where trenches pass from a footway to a roadway or at other positions where a
change of level is necessary, the bottom of the trench shall rise or fall gradually.
The rate of rise or fall shall be approved by NG.

Trenching with mechanical means where minimum of service utilities exist shall
be permitted at the discretion of the NG. In known places of dense existences of
electrical/other services only manual excavation shall be permitted taking extra care
and protection in doing so. All protective covers, warning tapes, position markers,
etc., pertaining to existing underground utilities shall be preserved during
excavation and restored in position during backfilling.

Whenever a crossing is made to an existing pipe or cable or other services/utilities,
such pipe or cable or other services/utilities shall be securely supported during the
progress of the work. The minimum recommended spaces or clearances required
between services shall be in accordance with approved NG standards.

In clear or open areas of cable route where embedded other utilities do not exist
such that the use of heavy machinery/equipment (excavator, backhoe loader, etc.)
is permissible, safe positioning and clearance or distance from the trench must be
observed so as to avoid equipment tripping over or overturning. A flagman /
signalman / banksman must also be deployed to communicate with the operator
during work execution.

If ground conditions along the route such as presence of rocky strata or high water
table where no probable or alternate geographical cable route has been determined
during the base design phase but to proceed with the said route, the following shall
be done:

Rock/Limestone/Clay Strata – (a) Blasting especially in open areas, if provided
by law in the locality, may be performed but under the direct supervision of a
licensed shot firer. However it must not be done if within road reserve where
other utilities are in close proximity. While doing so, extra care shall be carried
out taking into consideration the appropriate safety and environmental
protection measures including noise control; (b) Otherwise if the conditions do
not allow, mechanical means such as jackhammer and the like may be utilized
for the purpose.

High Water Table – In situations where the trench becomes flooded, dewatering
must be performed by pumping either to a storm water drainage or municipal
sewage system (prior local approval is required), or water tank trucks for proper
disposal. The trench shall be dry prior to compaction.

Unless otherwise agreed, provision shall be made during excavation and until
restoration has been completed, for reasonable access of persons and vehicles to
property or places adjacent to the route. Traffic safety shall also be implemented.

The materials excavated from each trench shall be placed so as to avoid nuisance
or damage to adjacent ditches, drains, fences, gateways and other property or
things. Excavated material shall be stacked so as to avoid undue interference with
traffic. Where, owing to traffic or for reasons of safety or other considerations, this
is not permissible, the excavated material shall be removed from the Site and
deposited at an area reserved for this purpose. This material shall be returned for
refilling the trench on completion of laying as allowed or as necessary; surplus
material shall be disposed of by and at the cost of the Contractor.

If any hindrances in the form of rubbish heaps, scrap vehicles or materials, builder's
materials within or outside of the builder's temporary fenced area, or unused parked
vehicles in the line of cable trench excavation is encountered, the corresponding
people shall be liaised for its removal sufficient to enable to proceed safely with the
work.

When excavations for trenches have been accurately executed, notice shall be given
to NG so laying of cables can be started after the corresponding work permit had
been secured.
1.1.3
Sand Bedding

When cables are ploughed in, clean fine sand as per specification and of prescribed
thickness must be firmly or uniformly filled in around or surrounding the cable as
bedding or cover free from rocks or other hard formation after the trench bed or
bottom had been thoroughly compacted.
1.1.4
Cable Laying
1.1.4.1 Drum Inspection and Mounting/Setting Up

Upon delivery, the cable drum should be visually inspected for damage, which
may have occurred during transport. The manufacturer’s seal on the inner and
outer cable ends should be examined and the condition of armouring, serving and
sheath inspected for mechanical damage, corrosion and leakage of impregnating
oil. If the cable is found defective it shall not be installed and the cable shall be
returned to the supplier for replacement.

During installation the cable should be carefully examined for any sign of damage
as it leaves the drum. This is particularly important on the outer layers, where
drum batten nails can cause damage.

If it is necessary to roll the cable drum, it should be rolled in the direction indicated
by the arrow on the drum.

The drum should be mounted on jacks, cable trailer or cable stands such that the
cable is preferably pulled from the top and always in the direction opposite to that
indicated by the arrow. Lighter cables may be laid by mounting the cable drum on
its side on a truck-mounted turntable and laying the cable directly into the trench.
When pulling from large drums, i.e. over 2m in diameter, the cable should be
supported to prevent stressing the cable, from the drum to the trench on a suitable
ramp.

Alternatively, cables can be rolled directly into a trench from the drum mounted
on an excavator moving along the trench.

To limit the chance of damage to the cable prior to removing the cable drum
battens, a check should be done to ensure that the drum-spindle is level and
permits even rotation of the drum.

During pulling there is a tendency for cable slack to accumulate on the drum, slack
shall be avoided and one possible method to achieve this is to limit drum rotation
by using plank brake shoes against one or both flanges of the drum. If the inner
end of the cable on the drum, referred to as the”Z” end, protrudes through the side
of the drum, then it should be watched during pulling to ensure it is not damaged.
It is advisable to tie a rope to the Z end, and pull through any slack cable that
appears. Pulling through Z end prevents buckling, and possible damage to the
inner coils on the drum.
1.1.4.2 Drum Positioning

Cable drums shall be positioned in line with the direction of cable pull.
1.1.4.3 Protection of Cables from Damage

Cables being drawn into place shall be kept clear of abrasive surfaces by suitable
means, e.g. rollers, cable tiles, etc., to prevent any damage to the cable sheath. The
cable must be placed in the trench without sustaining abrasion damage, and
without allowing rocks etc., to fall into the trench.

If the cable is hand flaked directly from cable drum or coil into final position or
other method that does not drag the cable over ground, cable rollers are not
required.

On long cable runs where a cable changes direction, both horizontal and vertical,
rollers shall be used to ensure a smooth pull and avoid damage to the cable.
Cables, which are pulled into position by a winch, must use suitable cable
stockings and swivels to prevent damage.

When laying cable by directional drilling, it is essential the cable is not dragged
over ground outside the drill hole or prepared trench, since abrasion is likely to
damage the outer jacket and cause sheath faults.
1.1.4.4 Cable Pulling Tensions

The tensions of the pull shall not exceed that specified by the manufacturers for the
particular type and size of cable being pulled and shall be smoothly and
continuously applied.

The trench or duct line should be set out so that any necessary deviations from a
straight line occur over the largest possible radius. When pulling cable into duct
lines incorporating bends lower maximum pulling tensions may be necessary to
avoid the wire pulling rope cutting into the side of the duct.

Any winch used to pull cables shall have either a facility to automatically limit the
pulling tension applied to a cable or a continuous reading dynamometer
incorporated in the pulling arrangement to enable the actual pulling tension to be
monitored.

Cable pulling pits are required at each significant change in cable route direction.
The pits will be indicated on the design drawing.
1.1.4.5 Pulling Speed

To avoid damage due to overruns, the cable should be pulled just fast enough to
keep the drum rotating smoothly.

Higher speeds are possible when pulling small cables into straight trenches or
ducts with good conditions at the feeding and pulling ends. Drums with long
lengths of cable, however, should not be rotated rapidly as overrun can cause cable
damage if pulling is slowed or stopped suddenly.
1.1.4.6 Cable Bending Radii

1.1.5
The permissible bending radii of all cables shall be in accordance with approved
NG standards. No twists, knots or kinks are permitted.
Installation of Pipes as Cable Ducts
1.1.5.1 Laying of the Cable Ducts in the Trench for Fiber Optic Cables

As per the PTS, Fiber Optic Cables shall be installed inside PVC ducts in the
trench at an approved depth as specified in the NG-approved IFC drawings.

Empty or spare ducts and sub-ducts shall be installed with a plastic rope or draw
wire inside for pulling purposes. All ducts shall be plugged with suitable endcap
to prevent ingress of water and any foreign material that may hinder in the pulling
of future cables.

PVC cement shall be used to join ducts.
1.1.5.2 Duct Banks (for both Power and Fiber Optic Cables)

All road crossings shall be ducted. This applies to present and future roads
indicated on the route plans. Ducts shall be laid and jointed in an approved
manner. These shall be surrounded by suitable thickness as per NG-approved IFC
drawings of encasement of concrete for existing roads and reinforced concrete at
locations of future roads for cable puling works.

After ducts have been laid they shall be thoroughly cleaned. A mandrel of
diameter slightly less than the pipe or duct shall be drawn through. After the
mandrel has been drawn through the pipes a draw wire or rope shall be left in
each pipe or duct to facilitate the drawing in of cables. The duct ends shall be
sealed temporarily to prevent the entry of foreign matter. End Caps and
permanent markers should be placed flush with the footpath/roadway at their
mouth ends. Pipes and ducts shall be cleaned again immediately before the cables
are drawn in.

The top surface of the concrete encasement of the duct bank shall be applied with
red concrete as specified prior to final backfill (selected base material).
1.1.6
Pulling Through Ducts

Care shall be taken to avoid damaging to the outer sheath of the cable where it
enters and leaves the duct. Single core bundled XLPE high voltage cables are
particularly susceptible due to their uneven shape and thin outer sheath.

A suitable lubricant should be used to reduce the friction between the cable and
the duct.

A tapered or belled entry shall be used at the entry end of ducts during pulling to
prevent damage to cable.

1.1.7
Cables shall never be installed in concrete ducts.
Cable Sealing
 On completion of the pull, any pulling eyes fitted should be removed and the cable
resealed unless about to do termination. Resealing is required to repair any
damage that may have occurred to the cable seal through pulling.
1.1.8
Installation of Cable Tile Cover, PVC-Coated Steel Wire Mesh, and Marker
Tape

Cable tile covers, pvc-coated steel wire mesh, and terra marker tape shall be laid
at the required levels, as shown in NG-approved IFC drawings.

Cable tile covers shall be laid evenly and follow the contour of the cable being
protected. Each cover shall interlock or be positioned closely to adjacent covers.

Chipped, cracked or otherwise damaged covers shall not be installed.

Tape shall be positioned directly above the cable. Joints in the tape shall be
overlapped for a distance of 1 meter.
1.1.9
Joint Bays

Construction of joint bays shall be, where required, with concrete rafts and formed
so as to enable jointers to carry out their work efficiently and expeditiously.

The method of securing and supporting cable joints and cables and also the
bonding and earthing thereof, shall be as per detailed IFC drawing approved by
NG.

The jointing will be carried out as soon as possible after receiving advice from
NG. However, if for any reason, the jointing cannot be done immediately, the joint
location may be backfilled with the consent of NG providing a suitable marker for
ease of future identification of the position. In such instances the cable ends should
be sealed. The sealing should be done by Heat Shrinkable Caps.
1.1.10 Timber Left and Built In

Where required for the security of the works or adjacent buildings or structures,
timber installed for the support of trenches, joint bays, headings, tunnels etc., shall
not be withdrawn but shall be left in position.
1.1.11 Filling In and Reinstatement/Restoration

Filling in of trenches shall not be commenced until NG has inspected/tested and
approved the cables (after laying/pulling and jointing) and accessories in situ.

All excavations made (whether for the purpose of cable laying or trial holes) shall
be restored to its original condition. The trench shall be back-filled, the earth in
each layer being well rammed and consolidated and sufficient allowance made for
settlement.

All worksites shall be leveled and left clean and tidy. Debris, trees, stumps and
excess soil dug from the excavation shall be removed from site when finished
trench backfilling

The backfilling and the interim restoration of the upper levels shall be completed
to the satisfaction of NG and in accordance with local regulations.

Permanent reinstatement of the upper levels shall be carried out after clearance
from the local government body.

All materials, stakes, plant, and equipment used during the activities shall be
removed and all worksites left in a safe condition.
1.1.12 Identification of Cables

All cables shall be identified below the gland at each end and at approved positions
by means of engraved bands or as per other NG-approved means stamped with the
cable number, feeder name, size of cable, number of cores, phase colour etc., or
such other lettering as may be required.

The bands shall be securely fastened in a permanent manner, and shall be made of
material able to resist corrosion, damp, and mechanical damage.
1.1.13 Earthing and Bonding

All cable sheaths and armour, supporting steelwork and the metal enclosures of
sealing boxes, joints, etc., shall be connected, or unless otherwise instructed, to the
main earth rod or bar by suitable branch connections which may be of bare or
insulated stranded conductor as required to suit the cable system.

The earthing conductors shall be copper strip laid in formed cable trenches or ducts,
or fixed to walls, concrete or steelwork, by means of clamps or claw type cleats,
appropriately secured into suitable wall plugs or tapped holes. The spacing of
fixings shall not be greater that 1 m. where earth strip is buried or laid in positions
in which there is danger of corrosion it shall be provided with a corrosion-proof
serving of extruded thermoplastic or self-adhesive PVC tape which for short
lengths may be hand applied on Site.

Cables having special corrosion protection coverings shall be bonded and earthed
through Link Boxes to facilitate the periodic voltage testing of outer coverings.
Concentric type bonding leads of suitable impedance shall be employed where
necessary. The bonding and earthing system shall also meet the subsequent
maintenance requirements.
1.1.14 Cable Jointing and Termination

All boxes or apparatus into which cables are terminated and suitable for use with
the cables shall be as per NG-approved IFC drawings.

No cable joint shall be installed without the agreement of NG.

The types of joints, cable sealing end, terminal box, gland and any other
items/accessories found necessary by NG should conform to the prescribed material
specification.

During jointing of the cables, the joint bays shall be shuttered to prevent subsidence
and damage and shall be adequately covered with tents or other water-proof
sheeting suitably supported. Proper precautions will be taken to guard against fire
and to ensure temperature and humidity conditions suitable for jointing operations.

All the power cables when entering the switchgear cable basement shall be done
through the ducts provided in the end walls. The ducts should be sealed with
approved fire-retardant or fire-resistant compound to prevent water penetration
and/or fire propagation after pulling the cables in cable basement of the substation.

The cable glands (termination points) are normally 3 - 3.5 meters above the cable
basement floor.

As necessary, approved galvanised steel work shall be supplied and installed for
supporting the vertical run of cables. The clamping of cables to steel work shall be
made with cast aluminum cleats at 1 meter spans starting from the cable gland
position.

The whole steel work should be of light structure and adequate strength for the duty
assigned. The steel work should be approved before installation.
1.1.15 Tests During Installation

A voltage test shall be carried out on the protective outer covering of each cable
length after laying, but prior to jointing and back-filling wherever applicable.

After completion of installation all sheath insulation provisions including external
joint and sealing end support insulation shall be subjected to the same test.

Ducts shall be provided for fiber optic cables at the open trenches and also for
power cables at all existing and future road crossings. Concrete-encased ducts
under the road shall be tested by non destructive method, if road cutting is not
permitted by concerned authorities. A mandrel test shall be performed to all the
ducts to ensure that the inside is smooth and free of any foreign materials so as not
to damage the cables.
1.1.16 Removal / Insertion of Links for HV Cable Tests and Primary Injection (Gassing
/ Degassing at GIS Terminations)

Wherever applicable, the degassing removal of the cable chamber links at the
remote ends, and regassing to facilitate HV cable tests and primary injection shall
be performed.

Once the tests are complete, the degassing, insertion of the links, and regassing
shall be completed thus allowing normal operations of the switchgear. This shall
include replacement of gaskets, 'O' rings, gas and all materials as necessary.

This activity shall be done in coordination with the Outage Plan as approved by
NG.