This method statement details the method related to sequence of installation of electrical works in order to achieve the wild air cooling for under construction building of large projects.
The installation of electrical works such as panel installation comprises the following activities.
Site Clearance.
Installation of necessary containment system.
Area clearance for Electrical Room, Plant Room, Sub-station, Transformer room, LT Room, HT Room.
Motor control center installation.
Installation of power cables in containment system.
VFD & controls installation for the mechanical equipment’s.
Installation of Bus duct system.
MLTBs, MSB, ATS Installations.
Installation of required Transformer.
Power cable termination in the respective panels.
Site Clearance
- Check all Civil finishing works are completed in respective area before commencement of wild air installation / assemblies.
- Check all the required plinths are made for the panels (such as MCCs, MSBs) as per the approved drawings.
- Ensure all the containment, cabling route and bus bar route are clear interim Civil finishing works.
- Check all the sub-stations are clear for the installation of panel including trenches, floor finishes, supporting arrangement, wall finishes, doors and railing arrangement as per the approved shop drawings.
- Check the Electrical rooms / Electrical cupboards are ready for the installation including the floor, wall finish, door installation.
- Ensure that the civil works related to the earthing systems are completed.
- Check all the plant room civil works are completed including wall / floor finishing works and door installation works.
Transportation and Field Inspection
- Transportation of cubicles to be witness by the Consultants.
- Pre-Installation inspection will have to carried out by the Site Engineer and installation Supervisor.
- The installation supervisor will instruct all relevant trade man regarding the sequence of execution works and distribute all necessary approved construction drawings of the latest revisions.
- The supervisor will also check that all correct tools and equipment’s are available for the works to be carried out.
- All the routes will be inspected by the supervisors for safe and unobstructed transportation from the offload area to the final location of particular electrical equipment.
- Prior to shifting and erection / assembly of switchgear equipment, inspection will be carried out to ensure no damage to cubicle or electrical components has been sustained.
Sequence of Work for Wild Air Electrical Installations
Cable tray installation will be carried out as per the approved shop drawings related to wild air cooling and as per the cable tray installation method statements submitted and approved for the project.
Installation of power cables will be carried out as per the approved shop drawings related to wild air cooling and as per the method statement for power cables submitted and approved for the project.
Motor control centre installation will be carried out as per the approved shop drawings related to wild air cooling and as per the MCC method statement which is separately submitted and approved for the project.
Installation of VFD will be carried out as per the approved shop drawings related to wild air cooling and as per the Method statement submitted and approved for the project.
MSBs will be installed as per the approved shop drawings related to wild air cooling and as per the method statement submitted and approved for the project.
Installation of Bus duct Systems will be carried out as per the approved shop drawings related to wild air cooling and as per the Method statement submitted and approved for the project.
ATS installation will be carried out as per the approved shop drawings related to wild air cooling and as per the method statement for ATS installation, submitted and approved separately for the project.
Installation of MLTBs will be carried out as per the approved shop drawings related to wild air cooling and as per the Method statement submitted and approved for the project.
Transformer installation will be carried out as per the approved shop drawings related to wild air cooling and as per the transformer installation method statement submitted and approved for the project.
Power Cable Termination
Where cable conductors are to be fitted with cable lugs, these will be of the compression type secured by either manual or hydraulic powered crimping tools, appropriate to the size of conductor / cable lug being fitted.
No aluminum conductors will be used within any switchboard.
Where conductors are to be terminated into switchboards the following procedure will be followed:
Cable sizes from 2.5 mm² cross section (inclusive) will be fitted with pin-type compression lugs, only if bolted connections are not practical.
Where conductors are to be terminated into switchboards the following procedure will be followed: Cable sizes greater than 10.0 mm² cross section will be fitted with compression – type lugs in conjunction with bolted terminals.
In all instances where compression type terminations are used they will be attached by using an manual / hydraulic crimping tools.
In cases where conductor / terminal shrouds are to be used and where terminals have insulating barriers fixed over them, inspection will be carried out to ensure these have been correctly installed.
Cable segregation will be adhered to throughout the installation.
All outgoing circuits will be color coded according to the phasing.
Shorting links for current transformers within switchgear equipment will be provided and used according to the status of equipment.
When the shorting links are not in use, they will be fixed securely adjacent to the relevant terminals of the current transformer (CT) circuit.
Where status indicator lamps are fitted these will be inspected for correct mode of operation and color coding.
Where cables are required to enter the manufacturer’s enclosure, a hole will be drilled using a proprietary hole saw.
The removable gland plates will be removed for drilling and refitted.
Where removable gland plates are not provided the enclosure will be drilled with extreme care to prevent the internal components being contaminated with dirt etc.
The internal components will be covered with plastic sheets, which will be attached to the interior casings of the switchgear equipment with adhesive tape to prevent entry of foreign matter.
Cut edges of the enclosure will be de-burred of any remaining metal work and treated with paint to prevent corrosion.
Prior to energizing distribution boards and switchboard and prior to the substantial completion of works their interior will be vacuum cleaned to ensure the removal of waste, dirt etc.
All auxiliary circuits will be installed using PVC insulated copper cables.
Where conductors are connected to Klippon type terminal connections the correct size of screwdriver will be used to prevent damage to the terminals and terminal insulators.
After termination has been completed it will be confirmed that the installation of end sections, partitions, brackets, cross connections plugs, jumper bars, warning labels, plastic screws, marking tags etc. have been correctly fitted.
Only one cable will be connected to each terminal. Where more than one cable of the same potential requires terminating together than adjacent separate terminals will be used for each cable, with a shorting bar or cross connection plug linking the two terminals.
Terminal blocks for the live conductors will be covered with an appropriate label and separated from other terminal blocks by partitions.
Where wiring is not enclosed in plastic slotted trunkings enroute for final connections to MCB’s etc. they will be installed neatly and orderly and be retained by using nylon type straps.
Field test to be witnessed and approved by the consultants prior to energizing the panels.
Test reports will be submitted.
Check earthing to be as per the approved drawings, the exact route to be coordinated at site.
Pre Commissioning of Wild Air System
When the wild air equipment and relevant electrical installation reaches the pre-commissioning test stage the Sub-station / HT Room / LT Room / Electrical Room / Plant Room will be made secure and access will be limited to Authorized personnel only.
At this stage as “Permit to work” system and a key issue system will be operated and come under the jurisdiction of nominated personnel.
Access for all contractor required to carry out in the secured areas will be controlled by nominated personnel.
Before energizing any part of the electrical distribution system the testing results should be acceptable, all terminals are checked and secured, all covers and safety shields are in place.
All section personnel will be informed and relevant “Supply Present” indication notices are displayed in both English and local languages.
The supervisor in charge and the QC Inspector will monitor the activities to ensure that all components indicated on the approved construction drawings have been installed and that the installation complies with the contract requirements and it will be verified that the completed installation complies with the project specification.