GAIL (India) Limited

25CHAPTER 6LIGHTNING PROTECTION1. Scope:This specification is intended to cover the requirements of supply, installation and testing of lightningprotection system at plaices specified by the department.2. Standards:The lightning protection system shall conform to the 1S: 2309/1989 and National Electrical code.3. Terminology:i) Air termination (lightning conductor) or Air termination network. Those pans of lightning protectionsystem that are intended to collect the lightning discharges from the atmosphere.ii) Bonds: Electrical connection between the lightning protection system and other metal work, and betweenvarious portions of the latter.iii) Down conductors: Conductors, which connect the air terminations with the earth terminations.iv) Earth terminations or earth terminations net work: Those parts of the lightning protection system whichare intended to distribute the lightning discharges into the general mass of the earth. All parts below thetesting point in a down conductor are included in this term.v) Earth electrodes: A metal plate, pipe or other conductor or an array of conductors electrically connected tothe general mass of the earth. These include those portions of the earth terminations that make directelectrical contact with the earth.vi) Lightning protection system: The whole system interconnected conductors used to protect a structure fromthe effects of lightning.vii) Side flash: A spark occurring between nearby metallic objects or between such objects and the lightningprotection system to earth.viii) Testing points: Joints in down conductors or in bonds or in earth conductors connecting earth electrodes,so designed and situated as to enable resistance measurements to be made.4. Materials to be used:Materials to be used in the lightning protection system shall be reliably resistant to corrosion oradequately protected against corrosion. The materials to be used are.i) Copper: Solid, or flat copper strips or stranded copper wire of 98 per cent conductivitywhen annealed, shall be used.ii) Galvanized: It shall be protected against corrosion in zinc coating.5. Lightning protection system:5.1 Air terminations:The lightning protection system comprises of the following major components.i. Air terminationsii. Down conductorsiii. Joints and bondsiv. Testing pointsv. Earth terminationsvi. Earth electrodesvii. FastenersIt shall consist of a vertical conductor on a tall structure, a single horizontal conductor for a small buildingand system of horizontal and vertical conductors for the protection of bigger buildings.