1. Design and installation of lightning protection and earthing system to be in strict accordance with SANS Codes of practice 10313 (2012), 10199 (2016) and 1063 (2015) in conjunction with SANS 62305-1-4 (2011) and IEC 62305-1-4: 2010.
2. All earthing conductors to be bare copper earth wire or galvanised steel except the instrument high quality earth system where PVC earth conductor should be used.
3. The number and depth of extensible copper earth electrodes at each earth termination to be determined by a soil resistivity survey, to ensure that the resistance value before and after bonding into the system will comply to the SANS standards.
4. Cable racks and gantries etc. to be bonded to structure wherever they enter the structure perimeter.
5. Roof steel sheeting of a structure to be securely bonded to earth at all corners of structures as shown. Bonding to include the steel gutters, downpipes and other metallic surfaces. Lightning protection down conductors to run next to rainwater down pipes where applicable.
6. All earth electrodes for the earthing of lightning protection and the earthing of electrical equipment to be driven into the ground if possible, or installed into pre-drilled holes and backfilled with an electrical conductive compound (Mitronite). Top of electrode to be cadwelded to the bare copper earth conductor. The maximum depth of the pre-drilled holes to be up to 15 metres.
7. The overall earth resistance value for the substation earth grid system, alternatively instrumentation earthing system, should be less than 1Ω and for overall structures, less than 10Ω.
8. Earth resistance test measurements, based on the fall of potential method, to be conducted at selected test points where cast iron test boxes have been installed for re-testing the various systems.
9. After completion of lightning protection and electrical equipment earthing system resistance test certificate must be supplied, fully in compliance with the relevant SANS standards.
