EXTERNAL LIGHTNING PROTECTION SYSTEM AS PER INDIAN STANDARDS IS/IEC 62305-NBC 2016 GENERAL Lightning Protection System shall be in accordance with IS IEC 62305-3 & NBC-2016. Lightning Protection consists of external Protection for the building with Air termination, Down Conductors and Earthing and Internal protection for power lines with Surge Protective devices. AIR TERMINATION SYSTEM Material, Configuration and Minimum cross sectional area of air terminal & down conductors Air Termination mesh conductor and down conductors: 8 mm Aluminium alloy round conductor (50 mm2). Air Termination Rod: 10 mm, 16 mm & 40 mm solid Aluminium rods (combination of sizes JOINTS Aluminium accessories connection between Aluminium materials are necessary. Stainless steel accessories if connections are between aluminium and copper / copper coated materials. Earth Termination Conductor shall be of 10 mm solid copper coated steel conductor (minimum 100 microns min coating) Earth Termination Joints in soil shall be done with Exothermic welding. AIR TERMINAL HOLDER Conductors shall be securely fixed on the terrace by means of concrete with suitable fixing materials fixed on the roof by adhesive or cement mortar taking care of varying weather conditions. Plastic air termination conductor holder is not allowed. The minimum height of this air terminal holder shall be 50 mm to avoid the contact of conductor with water EXPANSION PIECE In order to take care the expansion of metal in summer and contraction in winter, expansion piece with suitable connectors shall be used at every 20meter distance of horizontal air termination mesh. JOINTS AND BENDS The lightning protective system shall have few joints as far as possible & air terminal & down conductor have to be straight. Where it is not possible, it should NOT be bent at 90 degree (right angles) & should have a curved path of 45 degree bend. DOWN CONDUCTOR SYSTEM In order to reduce the probability of damage to electronic/electrical equipment, the down conductors shall be arranged in equal distance in such a way that from the point of strike to earth, several parallel current paths exist& length of the current path shall be minimum. Down conductors shall be installed at each exposed corner of the structure as a minimum. Maximum distance between down conductors shall be as per the table above TEST JOINTS At the connection to the earth conductor, a test joint should be fitted on each down conductor at a height of one meter from the ground, except in the case of natural down conductors combined with foundation earth electrode. The purpose of test joint is measure the earth resistance value. The remaining portion of down conductor (i.e., after the test joint should be mounted inside a PVC pipe of minimum 3 mm thickness. QUALITY & CONFIRMATIONS All materials and accessories shall be tested as per IEC 62561 for its mechanical / corrosion resistant / electrical conductivity. Vendor shall provide test reports along with completion certificate. GI (Hot dip galvanized or zinc electroplated) fixing materials and fasteners are not allowed.