The Scope of Work
7.1 Pre-Installation Activities
1) Ensure that route, areas, ducts to
pulled or laid with cables are inspected and approved and clearance is given.
Check the availability of proper cables to be used and ensure that these are
approved. Ensure that the latest approved drawing shall be used.
2) Cable drums shall be unloaded at the
place of storage or at the installation site. Within the site, the drums shall
be transported using high ups, forklifts or power shovels etc. For short
distance the cable drums can be shifted by rolled over.
3) Cables shall be identified with regard
to type, size, length etc. and shall be inspected for any physical damage. The
cable shall be free from any damages and the ends shall be sealed with caps to
prevent the ingress of water during transportation or storage.
4) Calibration certificate for testing
tools & equipment that will be used on site shall be
be submitted along with testing commissioning inspection.
7.2 POWER CABLE PULLING WORKS
7.2.1 Cable Pulling and Laying on
Cable Ducts
1) Route measurement shall be done and
identification of drum placement points to be marked with peg marking withdrawn
numbers prior to material shifting.
2) All necessary precaution shall be
taken while unpacking the cable drums or removal of battens to avoid damage on
the cable.
3) Rolling the drum shall not be allowed
for longer distances and shall be ensured only in the direction of arrows
marked on the drum.
4) Check and ensure that the cable ducts
or draw pits are clean, free from debris along the route. Duct internal has to
be checked by using a correct size of mandrel and clean by using rags tied to a
rope and pull back and forth from both ends and check that it is free from any
sharp edges. Ensure that the ducts ends are free from sharp edges.
5) Provide the identification on all
ducts as per approved shop drawings to ensure that the correct usage of ducts
and the correct members of cables will pass through.
6) Length of the cable route shall be
measured to verify the length of cables required.
7) Place the cable drums closely as
possible to the location where the cables are to be laid.
8) Wherever necessary, cables have to be
applied with approved pulling compound for smooth and easy pulling when
entering the cable ducts and cables have to be fixed with bell mouths.
9) Good communication measures or devices
shall be used or maintained for a safe and good cable pulling /laying
operation. Two way radios shall be used for communication.
10) Both ends of the cables shall be capped or taped and
sealed with heat shrinkable caps and proper identifications shall be provided.
11) All cables inside the cable pit shall be provided with
necessary supports as per approved shop drawing.
12) All cable ducts including spares shall be sealed with
an approved sealant. Clean all draw pits and place the required cover as per
the approved drawings or specifications.
13) Cable pulling and laying has to be done after the
inspection and approval of route, areas or ducts are obtained.
7.2.2 Cable Pulling and Laying on
Trays/ Trunking
1) Prior to shifting the cable drum to
site, check the cable data (ie. cable size, type, number of cores, length,
etc.) against approved shop drawing and cable schedule.
2) Setup the cable stand correctly for
even feeding of the cable. Each stand must be in line with each other. Avoid
the angle in which the cable will be feed from the reel to the tray.
3) Jack the cable drum enough to give
clearance from the floor slab.
4) Check the cable containment is ready
and the route is clear of any obstruction.
5) Remove steel binding straps and
retaining battens and timbers. Any expose projecting nails must be removed.
6) Before unreeling cable, double check
again cable size, rating and type of the cable inside reel. Confirm the data
obtained is as per approved cable schedule/shop drawings.
7) Inspect the tray/trunking supports.
Verify that they are properly fixed.
8) An approved permanent marker shall be
put at each end to identify the cables.
9) The ends of LV cables are sealed
during and after installation. Approved tape or heat shrink tube shall be
wrapped around each end of cables.
10) Cable drum has to be supported so that the cable(s) may
be unreeled and fed into the tray without being subjected to a reverse bend as
the cable is pulled from the reel.
11) Select the correct pulling grip. When selecting a
pulling grip, it is extremely important to select a grip of the correct type,
size and maximum rated based on the diameter of the cable.
12) Feed the cable to the tray at starting point and pull
the rope without unreeling cable on the drum to develop certain pressure
between cable and cable grip until it fully grips the cable.
13) All workers assigned at cable reel location shall
manually roll drum and unreel cable. During the entire pull, only the person in
charge i.e Supervisor or Foreman should give command to workers pulling the
cable in order to synchronize with the workers releasing cables at drum end.
14) Pull in the direction that will require the lowest
amount of pulling force.
15) After the cable has reached the other end, measure the
exact length required for termination to the equipment/panel board. Provide
enough allowance (slack) for every termination point before cutting the cable
at drum end.
16) Arrange the cable in the tray (follow correct spacing
as per approved drawing).
17) Immediately secure the cable to the tray by using cable
suitable plastic/aluminium cable cleats/clamps strap/tie. Spacing of cable tie
should not be more than 1.5 meter or as closed as required. Cable tie and clips
will be used for fixing of smaller size cables running in vertical cable tray
and for larger size cables, proper clamps will be used.
18) Measure the required length of cable at drum end to
terminating point and unreel it from the drum. Provide adequate slack also for
termination.
19) Afterwards, cut the cable from the drum and separate
each phase of the cable in preparation for another insulation test.
20) Good communication measures or devices shall be used or
maintained for a safe and good cable pulling or laying operation. Two way
radios shall be used for communication.
21) Engineer's approval for each and every piece of
material used in the process must be obtained prior to execution of the work.
22) Cable pulling and laying has to be done after
inspection and approval of installation of cable trays/ trunking are obtained.
23) The work shall be executed according to approved shop
drawing.
7.3 CABLE TESTING & COMMISSIONING
1) At the completion of each cable
installation and prior to the connection of any service installation, the
insulation resistance and continuity of all cables shall be tested.
2) An insulation resistance test will be
applied between conductors. Test voltage shall be 500VDC on domestic PVC wires
and 1000VDC on armoured cables with an approved, calibrated instrument and a
continuity test will be applied for each conductor and the readings for each
test shall be recorded on the attached test report form.
3) The insulation test reading should not
be less than 1 MΩ and the continuity test reading should not exceed 10M Ω.
Thus:
Test Voltage (IR): 500VDC/1000VDC
Continuity Test ≤ 10.0 Ω
Insulation Resistance Test ≥ 1.0 MΩ
4) If this not the case, cable must be
identified and replaced.
7.4 CABLE GLANDING & TERMINATION
· Check
contact surfaces of cable terminations. Brush if necessary and wipe with dry
cloth.
· Check
size of the panel enclosure knockouts, both incoming and outgoing cable.
· Guide
cable into connection compartment.
· Cut cable
to length and prepare end for glanding. Adopt reducer rings and fit to the
cable.
· Install
cable tags, name as specified in the design electrical schedule in the shop
drawings.
· Electrical
panel, light switch and power sockets shall be connected to locking screws
according to each terminal (live, neutral, earth) or marked/ identified
terminal.
· Cable
glands, cable lugs, crimping tool shall be used during cable termination.
· Cable
lugs bolt screws shall be torque tightened as per required torque figure.
· Lock
terminal screw for wire, must ensure proper tightness and application to each
terminal.
· Wiring
devices are identified to the “Distribution Panel” for each ampere schedule and
location to which they are connected.
· Remove
the knockout prior to mounting the enclosure. On multiple ring knockouts remove
the center section by striking at the point furthest from the tie. Bend the
knockout back and forth to break the tie.
· Use
knockout punches where possible to prevent burrs.
· Use a
small magnet to remove any metals shaving from enclosure.
· If a
larger opening is required, remove each additional ring one at a time by prying
with a screwdriver and bending back and forth with pliers.
· Use
approved cable clamps (lock nuts) or conduits hubs in the holes to secure the
conduit pipes going to panel enclosure and protect the cable and conductors.
· Carefully,
installed the conductors into the raceway to prevent nicks and other damage to
insulation.
· Replace
conductors if the insulation is damaged.
· Assemble
the panel interior components and tight the screws and bolts properly.
Separate the phases conductors to two categories as one will be
terminated from left side breakers and the other will be terminated to the
right side breakers.
· Separate also the neutral conductors for all
circuits which will be terminated to the neutral bus.
· Separate also the ground conductors for all
circuits which will be terminated to the ground bus.
· Tie each group of phases conductors with
cable ties till the first bottom branch circuit breakers.
· Tie each group of neutral conductors and
ground conductors with cable ties till the neutral and ground bars.
· Adjust the length of each conductor to be
able to reach its corresponding circuit breaker, neutral bar or ground bar.
· Label each conductor as per panel schedule
and as per specs.
· Strip the insulation from the end of each
conductor by using approved tools.
· Don’t allow loose strands of conductor to
stick out from terminations.
· Connect the main conductors to the mechanical
lugs of the main circuit breakers.
· Don’t install more than one conductor under a
mechanical lug or termination.
· Connect the branch circuit conductors to the
mechanical lugs of its corresponding branch circuit breakers.
· Connect the neutral conductors and the ground
conductors to the neutral bar and ground bar respectively.
· Assemble the dead front, the trim and access
door of the panel board and securely tight the screws and bolts.
· Provide circuit directory to the door for
listing which breaker provides service for each assigned cable termination.
· Do the torque as per the requirement.
Raise
request for inspection of cable termination.
7.5 INSTALLATION OF DB/SMSB & OTHER ELECTRICAL PANELS:
(IF REQUIRED)
7.5.1 Pre-Construction Activities Panels
· SMDB/DB
Panels shall be unloaded with care to avoid any damages. If they are shipped in
packs or pallets, each pack of pallet shall be lifted individually with
suitable lifting equipment.
· Hydraulic
trolley shall be used for lifting the SMDB in position during installation.
· A
mobile scaffold shall be used for securing the SMDB, DB on the wall and for
cable routing and termination.
· Every
precaution shall be taken to preserve their integrity and cleanliness before
installation.
· Store
in accordance with manufacturer’s instructions, properly protected from
construction activities and weather conditions.
· The
installation of SMDB/DB Panels shall be as per approved shop drawings and
coordination drawings.
· Ensure
all required documents (i.e. Associated method statements, shop drawings and
material approvals) have been obtained.
· Before
commencing any of the panel board installations, NAT must liaise and get
approval from the architect for completion of finishing works as applicable
(Plastering and final coat painting).
· Ensure
that Latest and approved schematic diagrams, load schedules, room layouts,
section details, installation details etc., should be made available prior to
start-up of site work.
· Necessary
certification for plant and electrical equipment must be provided.
· 240V
tools if used will be operated through a Residual Current Circuit Breaker
(RCCB).
· Calibration
certificate for testing tools & equipment that will be used on site must be
submitted.
· Ensure
that the Factory test reports for components of SMDB / DB/ Panels are approved
and reviewed upon delivery at site and to be re-tested prior to installation,
to ensure a fault free installation.
· The
site supervisor/ site Engineer will brief the team on the RAMS for the works
and explain the safe system of work and residual risks related to the task to
the work force.
· All
the Training records and RAMS shall be kept available on site.
7.5.2 INSTALLATION OF SMDB/DB ELECTRICAL PANELS. (IF
REQUIRED)
· Site
Engineer shall check and verify the correct location, position and height of
the SMDB/DB Panels to be installed on site with approved shop drawing.
· SMSB,
DB panels/UPS shall be off-loaded using manpower and with the help of trolley
and shall be installed on site using a suitable hydraulic trolley.
· Mark-up
the location of the SMDB/DB Panels once the final paint on the wall/floor has
been completed.
· Drill
holes on the concrete wall foundation following the depth and position as
specified in the approved shop drawing.
· Clean
and remove the dust on the drilled holes.
· Insert
the threaded rod into the hole and ensure its straightness. If needed, provide
adequate support to SMSB/DB Panels.
· Lift
and place the SMSB/DB Panels on the concrete wall by manual means or by means
of a suitable hydraulic jack.
· The
SMDB/DB Panels shall be positioned in such a way that the entry hole for the
supply cable at the metal base frame of the SMDB/DB Panels shall be accessible
easily.
· SMDB/DB
panels shall be installed vertically at 90 degree from the horizontal floor
level.
· SMDB/DB
Panels shall be fixed on the wall/rigid support frame with bolts and nuts.
Insert and tighten at every holding point location of the SMDB/DB Panels, at
the torque value of the respective bolts and nuts as provided by the
manufacturer.
· Ensures
clearance of not less than 1m in front of SMDB/DB, or as indicated.
· For
flush installation DB’s, all conductors shall terminate behind the board in an
adaptable box. For surface mounting, trunking shall be fixed between the board
and ceiling or floor level, or conduit run directly into Trunking which prevent
correct installation of the Trunking lid. Adequate earth continuity shall be
made between the various components.
· All
field wires shall be identified and terminated accordingly with earth
connection. Pull wires and/or cables inside the panels.
· Earth
connection shall be tighten properly to connections to assure effective
grounding.
· Terminate
the cables inside enclosures by securing the cables to switchboards with gland.
· Ensure
the load schedule in a clear transparent cover within the panels.
· Protect
the SMDB/DB Panels after installation. SMDB/DB Panels shall be thoroughly
covered with adequate plastic or paper material to prevent ingress of dust or
construction materials.
· Connect
the conductors to the input terminals of MCCB, the neutral conductor to the
neutral bar and earthing in the SMDB/DB.
· All
wires/cables shall be labeled using approved cable marker and equipment tag no.
for easy identification & maintenance.
· SMSB/DB
shall be protected from damage after installation.
7.5.3 DB PANEL CIRCUIT TERMINATION
WORKS:
1) All the 1st fix
& 2nd fix items shall be inspected to ensure they are
carried out as per the detailed drawings and fall in requirement of standards
as specified.
2) All the wires pulled will
be verified through megger (insulation resistance test) for any insulation
damages.
3) Upon confirmation, the
wires will be arranged as per individual circuit reference and tagging will be
done.
4) Based on the no. of power
circuit being used, MCB breakers will be connected to the existing DB or SMDB.
5) Based on the no. of small
power circuit being used, ELCB breakers will be connected to the existing DB.
6) Once all the circuit
verification & labeling are completed, the termination will be executed.
7) Upon termination
completion, the same will be offered for final inspection.
8) The final results of the
inspection shall be recorded on form for installation.
Mounting Heights for Electrical System:
|
Isolators |
1250 mm AFFL or as per Site
Condition |
|
Light Switches / Dimmer |
1250 mm AFFL |
|
DP Switches |
1250 mm AFFL |
|
Spur Units |
As per requirement |
|
13 Ampere Socket Outlets |
450 mm AFFL Or As per requirement |
|
Thermostat for
A/C |
1250 mm AFFL |
7.5.4 TESTING AFTER INSPECTION
1) Following checks shall be
done to ensure no leakage to earth.
A. Panel board and circuit
shall be checked.
B. All the distribution
circuits shall be checked individually.
C. All the outgoing circuit cabling
/ wiring shall be checked individually.
D. Earth leakage circuit breaker
(ELCB) trip testing to be done.
E. Prior to connection,
Insulation resistance for all outgoing wiring shall be done.
F. After termination of
cabling / wiring and main cables, the tightness shall be checked for all
terminations.
G. The result of the insulation
resistance shall be recorded on form NEC/PRJ/FRM-22/18, Rev No.01, Rev date:
20/08/18
2) Phase sequence check shall
be done.
3) Functional check of
Distribution Boards shall be done.
4) The final results of the
inspection shall be recorded on form.
7.5.5 COMMISSIONING OF DISTRIBUTION BOARDS
1) Make sure that the Main
Incomer MCCB is in OFF position.
2) Make sure that all the
outgoing circuit MCB’s are in OFF position.
3) Ensure the main supply
available at corresponding Isolator side.
4) Switch ON the main supply
from corresponding Isolator side.
5) Ensure the main supply is
available at the main incomer side from the corresponding Isolator side.
6) Check the incoming voltage
and make sure that the correct voltage and phase sequence is available at the
main incomer side.
7) Switch ON the main MCCB of
the panel board.
8) Switch ON the outgoing
MCB’s / ELCB’s of the panel board one by one.
9) Check whether the power
supply is available at the receiving ends.
10) Ensure that all QA/QC measures have taken
during all the activities.
7.5.6 TESTING
Before the start of the final testing & commissioning, make
sure to check the following items:
1. All the installation works are
completed as per the drawings & project specification.
2. All the Power Cables are terminated
properly.
3. Power supply for all the
equipment is ready & system is ready to start.
4. System should be checked as per
pre-commissioning checklist.
5. Panel board and circuit shall be
checked.
6. Prior to connection, continuity for
the loop wiring shall be done.
7. After termination of wiring, the
tightness shall be checked for all terminations.
8. The final results of the inspection
shall be recorded on form.
2. Risk
Assessment
All required safety precautionary measures shall be taken before
the start of the work and during the execution of this works as per the Risk
Assessment provided, refer to the attached risk assessment.