IEC 62305-3:2024

Overview

IEC 62305-3:2024 - Protection against lightning: Part 3: Physical damage to structures and life hazard sets requirements for protecting buildings and people from lightning-induced physical damage and from injury due to touch and step voltages around a lightning protection system (LPS). Applicable to the design, installation, inspection and maintenance of LPS for structures of any height, this third edition (technical revision) replaces the 2010 edition and clarifies methods, component requirements and new protective measures.

Key Topics and Requirements

• Scope and applicability: LPS design and measures to prevent injury from touch/step voltages for all structure heights.
• Air-termination systems: Minimum metal sheet/pipe thicknesses (see Table 4) to avoid hot-spot problems; maximum temperature rises (ΔT) and time durations (t50) for long strokes.
• Separation distance: Clarification and application of two calculation approaches - general and simplified methods for determining safe separation distances between LPS conductors and conductive parts of a structure.
• LPS components: Cross-reference to the IEC 62561 series to ensure use of reliable, standardized components.
• Air-termination conductor positioning: Revised positioning rules based on three accepted methods; detailed guidance moved to Annex D to match structural complexity.
• Continuity of steel reinforcement: Updated requirements affecting bonding and continuity in reinforced structures.
• New definitions: Introduction of “electrically insulated LPS” to distinguish from systems electrically and physically isolated from the structure.
• Annex updates: Annex C revised per subcommittee comments; Annex D now includes detailed methods, plus new guidance on green roofs and protection of protruding facade parts on tall buildings.

Applications and Who Uses It

IEC 62305-3:2024 is essential for professionals and organizations involved in lightning protection and building safety:

• Electrical and lightning protection engineers - LPS design and risk assessment.
• Architects and structural engineers - integrating LPS and ensuring continuity of reinforcement and conductor routing.
• Installers and contractors - following installation, testing, inspection and maintenance requirements.
• Facility and building managers - ensuring occupant safety from touch/step voltages and meeting compliance.
• Inspection bodies and authorities having jurisdiction (AHJs) - verifying conformity with updated technical rules and component standards.

Practical uses include designing complete LPS, choosing compliant components (IEC 62561), calculating separation distances, specifying air-termination layouts for complex and tall structures, protecting green roofs and facade projections, and preventing thermal/hot-spot damage in conductors.

Related Standards

• IEC 62305-1 (general principles of lightning protection) - referenced for overall risk management.
• IEC 62561 series - for LPS components and their performance and testing requirements.

Keywords: IEC 62305-3:2024, lightning protection, LPS, touch and step voltages, air-termination system, separation distance, IEC 62561, protection of structures, green roofs, façade protection.