Earthing
Often referred to as Electrical Earthing, Power Earthing, MES, or Grounding, the basic principle of any earthing system is to protect life and prevent injury which may be caused by electric shock.
Churchill Specialist Contracting have a wealth of experience in Electrical Earthing and offer a full range of services from the initial design stage through to commissioning.
With an impressive portfolio of major earthing projects successfully delivered so far, we have a workforce qualified to National Grid standards including temporary earth bonding formerly the National Grid NSI24 qualification, which is crucial to safety when working within an energised, or part energised power generation plant or substation.
Projects delivered successfully include London Power Tunnels, numerous major Energy from Waste Power Stations, Wind Farms and prestigious major top secret Military Facilities.
Supply and installation of Electrical Earthing
An earthing system could be as simple as a single earth electrode driven into the ground, or as complex as an underground grid of conductors covering thousands of square metres incorporating hundreds of connections to pile foundations, slab reinforcing bar, steel columns, equipment plinths and plant. This is commonly termed the ‘MES’, the Main Earthing System.
Above ground earthing is generally provided by strategically placed bespoke earth bars, or special connection points interlinked by secured cable or tape conductors.
Silfos brazing or exothermic welding of copper to copper joints with a continuity test to a millionth of an ohm using specialist equipment is standard practice. So too is our capability to provide and interpret a full fall of potential slope test for large earthing systems.
Earthing Design
The starting point of the design phase is the Wenner soil resistivity survey to gather the accurate resistivity of the ground strata. Using this and a whole host of other factors, specialist earthing software, CEDEGS, provides a comprehensive report and bespoke layout for the earthing system. A competitive quotation for supply, installation and commissioning of the MES is then produced.
Testing
Testing the MES in accordance with BS7430 and BSEN50522 is carried out by the fall of potential method. Single electrodes or small earthing arrangements are tested using the 61.8% method, more complex earthing systems require the slope method which can involve taking readings up to 1000m from the MES using specialist equipment.
Electric Vehicle Charging Points
Under the 18th Edition Wiring Regulations EVCPs installed on a PME/TNCS supply require an independent earth. Precise requirements are complex and are also set out in the Code of Practice for Electric Vehicle Equipment Installation. Generally speaking, if in doubt an earth should be installed. Churchill can install this for you or provide the materials as an earthing kit to be installed by others.
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