Electrical Engineers seldom show interest acquiring knowledge and experience on cable tray installations. Most of them think it's a concern of mechanical fabricators to be taken care of it. A proper and professional way of cable tray installation requires good involvement and coordination of people from both electrical and mechanical disciplines. If cable tray system has been installed appropriately in a project, following advantages can be counted:
- Cable Tray system enhances safety of electrical wiring system.
- Cable tray installation provides dependability in any circumstances.
- Cable Tray system saves space, materials, labor, time and cost.
- Maintenance and extension of cable tray installation are easier than any other wiring system.
Hence, electrical installation of a project must give high priority to adopt properly evaluated cable tray wiring system if aesthetic impact is low. This article explains how to make a typical method statement for cable tray or trunking installation for a building project.
1. Introduction and Scope of this method statement
2. Applicable Projects Specification
- Section: ELECTRICAL CONTAINMENT
- Division: INSTALLATION
- Sub Division: Subdivision
3. Location of Activity
Inside and outside the building.
4. Health and Safety Hazards
Specific safety measures have to follow as applicable, and all the safety measures are covered separately in the project safety plan.
- Materials: Materials used will be as per the material submittal approved by the engineer and routing as well and sizes will be as per the approved drawings in co-ordination with other services.
- Storage / Protection: Cable Trays, Trunking and Accessories 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. Every precaution shall be taken to preserve their cleanliness before installation.
6. Installation Of Cable Tray Or Trunking System For Building Electrical Services
- To make sure that the entire installation is in conformance and in accordance with the design intent of the project for the Electrical and Low Voltage System in addition to the specification and as per approved shop drawings and comply with Local and International Standards.
- Adhere to the drawings as closely as possible. The right is reserved to vary the runs and sizes of Cable Trays / Trunking and to make offsets but maintain as far as possible the free area of each duct work section, where necessary to accommodate conditions arising at the building.
- Before beginning installation in any area, examine all parts of the adjoining work onto which applicable work is to be placed. Should any condition be found which will prevent the proper execution of the work, installation shall not proceed in that area until such conditions are corrected by the contractor.
- Cable Tray / Trunking shall be stored on site under cover in dry, well ventilated storage facilities.
- Where sizes of Cable Trays / Trunking are not detailed on drawing then tray shall be adequately sized to support the cables without bunching and a 25% reserve margin shall be allowed in size and weight be loaded.
- All routes are chosen to allow ease of access to all cables when installed. All horizontal cables are to be set around all vertical rising services as necessary. Ensure sufficient clearance from soffit for every installation.
- Earth continuity conductors shall be provided across gaps in all Cable Tray / Trunking runs and bolted connections.
- Support shall be by means of steel brackets installed at intervals necessary to provide a rigid fixing and to ensure that deflection does not exceed 5mm mid span of support when fully loaded. Treatment of cut edges as per cut edges to be included. Supports for Tray / Trunking (spacing) shall be as per standard practice and manufacturer's recommendations.
- Additional support shall be provided where the Cable Tray / Trunking changes direction or cables drop out of the cable tray. Dome headed bolts, nuts and washers of finish suitable to the tray shall be used between trays.
- Suspension sets comprise threaded M10 zinc or cadmium plated hanger rods together with nuts and locking washers, supports channel hold down clips all of which shall have a galvanized finish. Any cut ends supports, rods, etc, must be corrosion protected by use of galvanized or equal. No extended rods to be left.
- The cable tray shall be installed with a 40mm minimum space between the structure and the tray.
- All cable shall be securely fixed to the tray, work and the complete installation must be carried out in a neat and workmanlike manner without crossovers.
- Cables on face-up horizontally fixed tray must be secured by use of the tie wraps where not in view. If cables are bunched or single cables greater than 25sq mm are installed, cleats or metal straps shall be used.
- Project Manager:
- To ensure that all the preparation and application works are carried out according to the Contract Specification.
- To ensure that the progressing of works is carried out according to the planned program and as per the approved method statement.
- To ensure that all equipment and material required executing the work are available according to the planned Construction Programme.
- To co-ordinate with the Main Contractor, MEP co-coordinator and Safety Officer for a safe and proper execution of the works.
- Site Engineer:
- To ensure that the works are carried out according to the Contract Specifications approved method statement.
- To provide all necessary information and distribute responsibilities to his construction team.
- To monitor the progress of work in relation with the work program and to report to the Project Manager.
- To co-ordinate with the safety officer and to ensure that the works are carried out in safe practicing methods.
- The foreman will carryout his duties by maintaining continuous coordination with the site engineer on daily basis, and ensure proper distribution of the workforce in the required and planned locations.
- To ensure that his assistant foreman/ charge hands are aware of the job requirements and they have enough information to carry out their duties properly.
- To ensure in consultation with the site engineer that the manpower involved in the works are moving as agreed and planned for the work.
- To ensure that the daily work is progressing as planned and advise the Site Engineer of any requirement for the additional resources.
- To control disposal of waste materials according to the instructions received from the site engineer.
- To ensure full coordination with the safety officer to maintain safe working and proper house keeping of the site, following the approved safety measures and further ensure that all his working team are aware of the same to prevent accident and losses.
- To inform the site engineer and of the areas ready for inspection.
- Distribution and the control of materials shall be monitored by foreman and storekeeper.
- Safety Engineer:
- Ensure the implementation of all the safety measures in accordance with the HSE plan and everybody aware of it for it's proper implementation.
- Ensure all the implemented safety measures are adequate to maintain the safe working on the site.
- Inspect all the site activities and train the persons to prevent accidents and its proper reporting to the project manager and the client.
- Ensure that the site is maintained clean and tidy.
8. Manpower Required
Charge Hand and Experienced Technicians
9. Inspection And Test Plan Format For Installation Of Cable Tray Or Trunking
|ITP Clause No||Inspection Description||Type of Inspection||Reference Document||Testing Requirement/ Acceptance Criteria||Verifying / Control Data Forms|
|1||Design and Drawings||Review of Documents||Design Drawings||All the Drawings||Design drawings, Authorities Departments Requirements.|
|2||Material Approval||Review of Documents||Approved Drawing, Specification||Should be as per the approved drawing and Specification||Documents Submittals|
|3||Check Installation of Cable Tray / Trunking||Visual||Approved Method Statement||Proper bends correct level and Location, route material should have minimum status of – No Objection with comments (2)||Approved Drawing Method Statement|
|4||Request for inspection of works||Visual Measurement Instrument, Earth Test||Approved Drawings||No obstructions Level, Routes||Approved Drawings|
10. Materials Requirement
Cable tray / trunking and accessories
11. Equipment Requirement
The equipment that will be engaged for Installation of Cable Trays and Trunking works will be as follows:
- Wire cutters
- Measuring tape
- Drill machine
- Wooden hammer
- Flat file
- Screw drivers
- Open and box spanners
- Base Cutter
12. Health and Safety
Strictly followed as per the manufacturer's Health and Safety recommendations for handling and use of the materials. Ensure all involved personnel shall be aware of the same.
13. Supporting Documentation
This method Statement should be read in conjunction with the below referenced documentations:
ITP for Cable Tray and Trunking
Copies of this method statement have also been issued to the following for information/ action/ comments:
- Project Manager
- Site Engineer