Technical Handbook

TECHNICAL HANDBOOK nVent ERICO Lightning Protection Handbook Designing to the IEC 62305 Series of Lightning Protection Standards Lightning Protection Consultant Handbook nVent Engineered Electrical & Fastening Solutions is a leading global manufacturer and marketer of superior engineered products for niche electrical, mechanical and concrete applications. These nVent products are sold globally under a variety of market-leading brands: nVent ERICO welded electrical connections, facility electrical protection, and rail and industrial products; nVent CADDY fixing, fastening and support products; nVent ERIFLEX low voltage power and grounding connections; and nVent LENTON engineered systems for concrete reinforcement. For more information on ERICO, CADDY, ERIFLEX and LENTON, please visit nVent.com/ERICO. Introduction This handbook is written to assist in the understanding of the IEC 62305 series of lightning protection standards. This guide simplifies and summarizes the key points of the standards for typical structures, and as such, the full standards should be referred to for final verification. This handbook does not document all IEC requirements, especially those applicable to less common or high risk structures such as those with thatched roofs or containing explosive materials. In many situations there are multiple methods available to achieve the same end result; this document offers nVent’s interpretation of the standards and our recommended approach. In order to provide practical advice, information is included on industry accepted practices and from other standards. NOTES: IEC® and national standards continue to evolve. This handbook was written with reference to the current editions of these standards as of 2009. Due to regional variations, the terms earthing and grounding may be used interchangeably. 2 | nVent.com/ERICO Key Terms and Abbreviations Term Definition Air-Termination Part of the lightning protection system to intercept the lightning flash (strike). For example, an air-terminal providing a protection angle to protected equipment, or horizontal or vertical conductor providing protection via the mesh method British Standards (BS) Body responsible for implementation of national British standards, identified by BS prefix CENELEC European Committee for Electrotechnical Standardisation (essentially European standard or Norm, identified by EN or NE prefix) Classification of lightning protection system. Class I, II, III, IV relate to the lightning protection level and define, Class (of LPS) for example, the different rolling sphere diameters to be used Earth electrodes Those parts of the earth termination system in direct contact with the earth, such as ground rods, buried wires, foundation earthing, etc Earth-termination Part of the external LPS to dissipate lightning current into the earth External lightning Air-termination(s), down-conductor(s) and earth termination(s) protection system Internal lightning Equipotential bonding and/or electrical isolation of the external LPS from internal conductive elements protection system IEC International Electrotechnical Commission, responsible for formation of International Standards Lightning protection Number assigned to represent maximum and minimum lightning parameters that should not be exceeded level (LPL) by natural lightning Lightning protection system (LPS) Complete system for lightning protection of structure. Includes internal and external lightning protection measures Lightning protection zone (LPZ) Zone where lightning electromagnetic environment is defined Mesh method (MM) Method to determine position of air-termination system Protection angle method (PAM) Method to determine position of air-termination system Rolling sphere method (RSM) Method to determine position of air-termination system Separation distance Distance between two conductive parts where no dangerous sparking (flashover) can occur Services Circuits and pipes, etc, entering into structure from external environment. Typically phone, power, TV, gas, water, sewerage systems, etc Surge protective device (SPD) Device for protecting electrical/electronic equipment from transient voltage damage nVent.com/ERICO | 3 Table of Contents 1. IEC AND EN STANDARDS 6 1.1 IEC 62305 series ��6 1.2 EN 50164 series ��6 1.3 Normative and informative .............................................................................................................................................................8 1.4 IEC terminology ��8 2. THEORY OF THE LIGHTNING FLASH 9 2.1 The thundercloud �� 10 2.2 Mechanics of the lightning strike �� 10 2.3 Lightning parameters ................................................................................................................................................................... 11 2.4 Lightning damage and risk management ...................................................................................................................................... 13 3. INTRODUCTION TO PROTECTION METHODS AND RISKS 14 3.1 Risks ��15 4. RISK MANAGEMENT 17 4.1 Overview of risk analysis �� 17 5. LIGHTNING PROTECTION ZONES 22 6. DESIGN PROCESS 23 7. MATERIAL REQUIREMENTS 24 7.1 Copper versus aluminum ��24 7.2 Use of dissimilar metals ��25 7.3 PVC covered and concealed conductors ��27 7.4 Tape, versus solid round, versus stranded ..................................................................................................................................................................27 8. NATURAL COMPONENTS 28 8.1 Metallic facades, profiles, rails, etc ��28 8.2 Use of steelwork ��28 8.3 Use of rebar in reinforced concrete ..............................................................................................................................................................................28 9. DESIGN METHODS 33 9.1 Rolling sphere ...................................................................................................................................................................................................................35 9.2 Mesh method ��37 9.3 Protection angle method ��39 10. AIR-TERMINATIONS 43 10.1 Recommendation on positioning ��44 10.2 Masts and antennas ��45 10.3 Protection of other items protruding above the roof ..............................................................................................................................................45 10.4 Bonding of roof top fixtures ��48

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