This method is to describe the minimum requirements for earthing conductor installation including materials receiving, storing, and installation.
The electrical procedure will ensure that the requirements of underground earthing installation works are met in accordance to the codes requirements and contract specifications.
Procedure will also make sure that the electrical works are carried out in acceptable workmanship and work follows the requirements of project.
Overall the site electrical engineer at site shall be responsible for the planning scheduling and coordination, record and monitor progress of underground earthing works. This method will also help in guiding the supervisors in the field in terms of engineering and technical problems.
Codes & References
Applicable manufacturer’s recommendation
Contract specifications and approved construction drawings for earthing system
Standards, codes and recommended practices
The field installation, inspection and testing of underground earthing system shall be executed under the responsibility of contractor according to the relevant drawings and documents.
Installation work shall be done according to good workmanship practices and by using the suitable tools and material as stated in the construction drawings, approve documents, and procedures and it shall be studied before carrying out any electrical works.
Full care and precaution shall be given by the field management for the safety and sanitation of workman in the field to prevent accidents during execution of the works.
For outdoor earthing of lighting poles etc. and junction boxes on the poles, two (2) nos. 25 x3 mm GS flat shall be tapped off from 25 x 3 mm MS flat buried in ground at a depth of600 mm.
Earth conductor shall be connected to the nearby main earthing grid at the first and last poles of each feeder circuit and at some intermediate poles. In case of lighting poles where the main earth grid is far away from the pole, local earth pits shall be provided for pole earthing.
Steps for Earthing Installation
Prepare the clamping tool for the jointing of the earthing cables.
To know that C clamp is installed correctly, measure the difference in gap in the jaws of the C clamp before and after clamping process.
Ensure excavation work in every building foundation is already finished, and the elevation of excavation is appropriate with the design level.
Install grounding cable in every building foundation, installation shall start from base excavation, and grounding cable must be in connection with the soil.
Make sure that all the connections of grounding cable are installed correctly.
For grounding cable rise up of the installation must be installed properly.