The purpose of this procedure is to define the step by step method to implement the correct practices for the pre-commissioning & commissioning of Earthing System through the guidelines contained herein so as to ensure that the job execution complies with the project requirements and serves the intended function to satisfactory level.
TOOLS / EQUIPMENT REQUIRED:
- Portable Hand tools
- Step Ladder
- Insulation Tester
- Earth Megger
The earthing system consist of a dedicated earth bus bar for each floor in the electrical room where all the earthing leads of the respecitve floor equipment are terminated. The earth bus bars of individual floors shall be connected to the main bus bar in the ground floor which shall drain into the earth pits.
Pre Commissioning Procedure for Earthing System
- Ensure that the Earthing System installation is complete and mechanical completion is approved & all comments on the installation are incorporated.
- Ensure that all types of grounding to the grounding electrodes are as per acceptable codes.
- Ensure that no damage has occurred between mechanical completion & pre-commissioning.
- Ensure proper termination of the earthing cables in the floor bus bar & the main bus bars.
- Ensure all contact surfaces of all ground connections are thoroughly cleaned.
- Replace damaged cables, if any
- Ensure the installation is in line with the approved shop drawings & manufacturer’s recommendations.
- Ensure all the earth bars are properly fixed to the wall & are freely accessible.
- Ensure the containment for the earth cables are properly supported & the earth cables are properly dressed.
- Ensure that all wall / slab penetrations of the cables/trays are sealed with approved fire sealant at each fire barrier penetration.
Commissioning Procedure for Earthing System
- Ensure that all the pre commissioning checks are carried out successfully.
- Ensure the earth bars are in level using spirit level.
- Check the continuity of the earth cables from the respective equipment to the floor earth bar.
- Check the continuity of the earth cables from the respective floor earth bars to the main earth bar of the respective building.
- Check the continuity of the earth cables from the respective main earth bar of the building to the earth pits.
- Check the earth resistance values at the earth pits individually & ensure that the value is less than one ohm.