This method statement for electrical work shall help you understand the requirements before and during the cable s and wires pulling process. The document is very helpful for MEP QA/QC engineers to develop the professional electrical method statement for their project.
Below is the list of equipment / Tools required for installation of cables and wires, which can be used for different projects after doing the customization as per the project requirements.
- Cutting Tools
- Hydraulic Crimping Tools
- Manual Crimping Tools
- Scaffolding Step Ladder
- Cable Drum Trolleys
- Cable Spindle s & Jacks
- Cable Rollers
- Measuring Equipment
- Pulling Wires, Rope, Lubricant (Soap-based, Wax Based)
- Hand Gloves, Fall protection and Other necessary PPE’s.
Installation Of Wires & Cables
- All materials intended for cables & wires shall be submitted for approval of the consultant as per the standard procedure using the Notification of permanent material received at site.
- Material samples shall be submitted as required by the consulting engineer for approval.
- The Supervisor will complete the inspection checklist and follow the Inspection & Test Plan detailed in this procedure. The intent of this procedure is to establish a high level of assurance that the end product meets the specification requirements.
- The QA/QC Inspectors should verify the approved procedures are followed and the inspections and testing records are completed.
TRAINING & QUALIFICATIONS OF PERSONNEL
- All operatives will attend safety induction along with the relevant document copies i.e. valid visa company ID copy, and copy of previous experience and training in the same job which proves his competency.
- Supervisor should closely monitor the activity, if he finds any operative is lagging on safe work competency, he will be sent for re-induction and even retraining if deemed necessary.
- Examine the areas to execute the work and the conditions under which the work will be performed. Identify conditions detrimental or unsafe for the proper and timely completion of the Work. Do not proceed until unsatisfactory or unsafe conditions have been corrected.
INSPECTION & STORAGE OF MATERIALS
- Submit Notification of Permanent Material Received on Site i.e. Material Inspection Request upon receipt of materials delivery to site. Attach Delivery Receipt, Material Submittal Approval and other documents to show complete compliance with specifications and QA/QC Plan.
- Any material found not as of approved material or with surface damage which is not rectifiable will be set aside. These materials will be labelled and returned to supplier warehouse and a Non-conformance Report will be issued to the supplier by QA/QC superior.
- Store materials in protected dry location off-ground in accordance with manufacturer’s instructions and to protect from mechanical damage or weather effects etc. Extreme care shall be taken while handling the subject materials.
- Lay down area at site to be coordinated with MAIN CONTRACTOR and arrangements to be made for unloading and / or mobilization of materials.
- Ladders / Scaffoldings to be secured firmly over the working platform and inspected by competent personnel and tagging system (green/red) are implemented, prior to start of work.
- Prior to commencement of work, the Engineers & Supervisor/Foreman will inspect all materials delivered to work place are checked for with their shipment check list and ensure they are the relevant piece for the site and materials are not damaged, without excessive scratches or visible corrosion.
- Only required materials to be shifted to site and stored temporarily and ensure extra materials are not dumped to site and congest the working area.
- Once work is completed extra materials and tools to be return back to stores, work area to be kept clean.
Pre Installation Requirements for Cables and Wires
- Ensure all drawings and electrical method statement are approved and available to the installation team.
- Prior to the installation of cables in any area, cable ladders or any containment system must be inspected and approved. Ensure that the factory test reports for continuity of the cables is provided and reviewed to ensure the fault free installation.
- Check that ladders/trays are free from any sharp edges and have sufficient space for installing the cables.
- Ensure that ladders/trays are provided with purpose made bends to accommodate the minimum bending radius of the cable. This is to ensure that cable is not given undue stress.
- PVC sleeves shall be installed for all cables passing through brick, block or concrete or similar structures in case there is need for future withdrawal.
- Non ferrous spacer clips for multiple runs and single fixing non-ferrous clips for single runs will be provided for cables fixed directly to the structure.
- Collect and keep ready at site materials such as cable pulling sleeves, tools, rollers and tackles etc.
- Complete a mock-up installation before main works and get its approval.
Wires Pulling Method
- Make sure that all conduits and boxes in both ends are free from damages and blockages etc and installation is approved.
- Blockage shall be checked by inserting the draw wire and checking that it reaches to the other end without any disturbance.
- Once the conduit is not blocked the wires shall be pulled using the draw wires while ensuring no damage occurs while pulling.
- Pulling compound or lubricant shall be used for pulling the wires where required.
- Use soap-based pulling compound for short runs i.e. less than 20 meters for semi conductive insulated wires.
- Use wax based pulling compound for the runs greater than 20 meters for semi conductive insulated wires.
- While pulling the wires care should be taken to not insert the pull tension greater than the manufacturer allowed limits.
Cable Pulling & Termination
Transport and place the cable drums as per drum schedule and at the locations where space is available for working. The cable drum shall be placed on a jack & spindle arrangement to ensure free rotation of the drum. Erect scaffolding where required as per the site requirements.
Cable rollers shall be placed under the cable during pulling over longer distances and standoff rollers for acute bends, to ensure that the cable is pulled with minimum effort and the cable outer jacket is free of scouring lines. The cable shall be pulled by using pulling means such as fish tape, rope and basket weave wire/cable grips so as not to damage cable or its containment system. Care will be taken to ensure that the maximum pulling tension of all the cables is not exceeded at any time.
Cable should be free of any static load i.e. to be places side by side parallel on the cable tray or ladders. Any kind of dead weight on the cable shall be avoided. At all times the cable schedule & section drawings for the relevant area will be referred to ensure proper location of cable on the required ladder and to ensure compliance with project specifications.
A pulling compound / lubricant shall be used where necessary as per site conditions i.e. in slabs and underground conduits etc, the lubricant should not deteriorate the cable insulation. The cables shall be secured to the containment system using approved cable ties for horizontal runs and cable cleats for vertical runs. All control cables will be installed at a minimum distance of 100mm from power cables unless otherwise agreed with consultant as per site conditions.
Earth (green/yellow) cables shall also be pulled along the power cables. At all time of pulling, mark both power and earth cables for pairing them on both sides of connection i.e. at sending and receiving ends. Before termination complete length and route of the cable shall be inspected by QA/QC engineer , after which a WIR shall be raised for consultant approval. Cable shall be caped and sealed on both ends after installation until termination is done.
Termination shall be done by using the approved termination materials that include glands, lugs and other accessories part of termination kit, by using proper crimping tools. Matching colour gland sheaths shall be provided. All termination shall be provided with tight fitting covering sleeves.
Insulation Resistance Test: Set the Meggar meter to 1000 volts DC for cables and 500 volts DC for wires. Take reading between phase, phase and neutral, phase and earth neutral and earth. Note that resistance reading must not exceed 2 mega-ohms (MΩ). Check and record the resistance readings as per specification on the approved insulation resistance test forms.
- Install the tags / labels as per project specifications and as per approved material submittal for Cables and Wires.
- Cables shall be identified at feeders i.e. the sending and receiving ends (outgoing cables in SMDB’s and final DB’s) about 50mm below the gland.
- Identification labels shall be provided at all positions where cables and wires change direction and each side of the wall or floor slab and where cables are in multiple runs.
- Cores of cables connecting control gear, thermostats, valves etc will also be identified and shall be fitted with identification sleeves bearing the same marking as the terminals of the apparatus to which these are connected.
- For cables at feeders, identification will be done as per specification and approved materials.
Alternative Procedure no: 1 for cables and wires installation and termination
Storage of Materials at Site
All materials received at site shall be inspected and ensured that the materials are as per approved material submittal. Any discrepancies, damages etc.shall be notified and reported for further action. Material found not suitable for the project are removed from site immediately.
Cables are stored with the factory packing on the flat surface with stoppers to prevent drums rolling, as demonstrated on the attachment. Protection shall be provided from direct sunlight. Wires shall be sorted and stored size-wise for easy retrieval. Wires shall be stored in covered and ventilated place.
Installation Procedure for Cables
- Ensure all the relevant current / approved shop drawings are available with the installation team.
- Transfer the cable to the work place with help of fork –lifts or crane and trailer. Enough man power shall be deployed.
- Handle the cable drums as recommended by the manufacturer for cable drum handling.
- Check the cable drum for any damage during transportation and test the cable for continuity and insulation resistance before installation with 500V Megger on (0-600V) cable.
- Check and ensure the cable support system throughout the cable route is completed and free from damage or sharp edges.
- Place cable roller on the cable route at every 1.5 meters and end bells at the bends.
- Identify the designated cable drum for cable pulling and raise the cable drum above the ground level with cable jack to unwind the cables to the pulling direction.
- Pull the cable with cable pulling machine or manually from one feeder end to the other end.
- Ensure no undue stress is applied on the cable which may damage the cable and its functionality. Recommended pulling tension by the manufacturer to be adhered to.
- Leave enough length of cables at both the ends for termination and cut.
- After pulling the cable check for mechanical damage, if any major damage found replace the cable with new one.
- Dress the cable with necessary cable ties of approved type and make (every half metres) and no overlap of cables shall be allowed.
- Maintain gaps between the cables as per standards / as required.
- In case of single core 630 Sq.mm cable, trifoil arrangement with cable touching along their entire length is adopted.
- Provide identification as per specification and approved material submittals.
- Installation shall be offered for QC verification and inspection by consultant.
Installation of Cables & Wires Procedure
- Ensure all the related documents like current / approved shop drawings and load schedules are available with installation team.
- Transfer the required amount of wires from stores to the crane access point by pickup and lifted by crane to the particular floor and / or with wheel barrow to the work place.
- Prior to pulling of wires, check and ensure there are not sharp edges or burrs in the raceways to prevent damage while pulling wires.
- Identify the correct size and colour. ( According to the specified colour coding ) of wire , cut to the required length.
- In case of trunking each circuit shall be taped or stapped together at intervals, and place the wires in trunking. Pulling is not allowed in trunking.
- Do not bunch two circuits together, if done so, for easy installation, shall be removed after installation.
- Pull the wires through conduits with the help of pull wires.
- Comb the wires in trunking for better flexibility during replacement.
- Ensure no joints are made in any circuit.
- Where trunking installed vertically, pin racks shall be provided at 3m centers to avoid strain on conductors.
- Leave a minimum of 250mm length or more according to the requirement which should be enough for connection to the desired terminals.
- Cover the trunking with appropriate covers (or) cover the pull boxes in case of conduits.
- Work Inspection Request shall be raised for Consultant’s inspection and sign off.
Alternative Procedure No: 2 for cable pulling and cables terminations.
Unloading of cables: When cable drum already unload on designated area, provide wooden block below the cable drum to prevent it from rolling and before removing the hoist cable, check the direction of arrow on the drum. It must be the same direction as the pull.
Jack-up the cable drum by means of hydraulic jack enough to give clearance from the floor Remove the wooden cover of the cable drum. Select the required pulling grip, when selecting a pulling grip, it is extremely important to select a grip of the correct type, size and maximum rated capacity. Measure the circumference of the cable and find the correct size.
Preparing for Cable Pulling: Remove all steel binding straps, retaining battens and timbers. Any expose projecting nails must be removed. Ensure that cable containment is cleared from any sharp edge to eliminate damage or scratches on the insulation cables. Install the cable roller on the cable tray on the entire cable laying area. Provide cable roller interval at 3 meters for straight run and corner cable roller on every change in direction. Connect the pulling rope to the cable grip using shackle and provide signal on other end of the rope for cable pulling.
Installation of Power Cables & Wires
Ensure during cable pulling that cables are properly aligned and no cable twisting will occurs. Use cable lubricant recommended by the manufacturer to help pulling tensions down.
After the cable has reached the other end, measure the required length for termination to the Equipment or Distribution board. Provide adequate allowance for every termination point before cutting the cable at cable drum end. Arrange the cable on the cable tray with approved cable spacing as per standards and specification. Layout of cables must follow as per design / installation drawings.
Where cable trays pass through floor or walls of a specific fire resistance, install the approved fire stopping materials as per manufacturer’s recommendation.
After obtaining the measurement, cut the cable from the drum and separate each phase of the cable in preparation for another insulation test. After cutting the cable separate each stranded and performs for another initial insulation test. Record all the testing result. After testing seal both end of the cable with PVC insulation tape. Provide proper cable identification and markings to prevent any obstruction and protection from any damage.
When work is completed, the work will be inspected and snagged by Electrical Inspection team and any works found not compliant will be replaced or fixed before the final inspection is raised. Ensure that all punch items have been cleared, all inspection records are signed and accepted by the client. Check that the signatures of the competent client inspector obtained where applicable and MEP Clearance can be given and the system is released for subsequent activities.
Cable Termination Method Statement
Termination (Use of Cable Stripping / Cutting Tools)
Tools for the cutting and stripping of cable or wire for termination includes wire stripper/cutter tools and retractable knives. Use of the wire stripper/cutter tool is preferred to the retractable knife for the stripping and cutting of cable or wire for safety reasons.
Cutting of power cables
The wire stripper/cutter tool is used in the following manner for preparing cable or wire ends for termination:
Determine the correct cable core or wire size prior to inserting the cable core or wire ends into the tool head for stripping. Squeeze the tool handles until the cable sheath or wire insulation is cut through to the metal. Stripping of cable core or wire ends is then carried out by removing the cut cable sheath or insulation.
The cutting of the cable core or wire using the tool cutter is carried out by inserting the end into the tool head cutter blades and then squeezing the tool handles. Where it is not possible, because of cable size or availability, the use of retractable knife is acceptable for wire stripper/cutter tool. It is important that in using this tool, care is taken in order to avoid injury. Blade of knife should be retracted or covered with suitable protective cover when not in use, at all times.