I have a query on earthing system design. One designer has submitted me an earthing plan which interconnects the earth electrodes meant for equipment earthing and those for lightning protection purposes. By combining the earth electrodes he achieves overall earth resistance below one ohm required by IS 3043 (Indian standard). But my question is whether this is an acceptable practice followed by industry or the earth electrodes of the two systems (protective earthing and lightning protection) can not be combined this way?
Would appreciate feedback. thanks in advance.
Answer from Didier Mignardot: When Lightning Protection System (L.P.S.) is implemented, all metal conductors (including the electricity distribution network) must be interconnected.
Everything is described in IEC standard 62305-3 (Protection against Lightning: Physical damage to structures and life hazard) and in particular in the following chapters (5.4 & 6.1 extracts):
Please refer to this IEC standard 62305-3 and also other part like :
- IEC 62305-1: Protection against Lightning: General principles
- IEC 62305-2 : Protection against Lightning: Risk assessment
- IEC 62305-4 : Protection against Lightning : Electrical and electronic systems within structures