IEC 62305-3:2010

Overview

IEC 62305-3:2010 - Protection against lightning (Part 3) specifies requirements for protecting structures from physical damage and protecting people from injury due to lightning-related touch and step voltages. Edition 2.0 (2010) updates the 2006 edition with technical revisions covering design, materials, installation, inspection and mitigation measures for a Lightning Protection System (LPS). This part is closely linked with IEC 62305-1 (general principles) and complements other parts of the IEC 62305 series.

Key topics and requirements

• Scope of protection: requirements for external and internal LPS to prevent structural damage and life hazard from lightning currents and associated voltages.
• External LPS: design of air-termination systems, down‑conductors, earth‑termination systems and use of natural components.
• Internal LPS: lightning equipotential bonding, bonding of metal installations, measures for lines entering the structure and insulation requirements.
• Touch and step voltages: measures to limit dangerous voltages in the vicinity of LPS and inside structures.
• Materials & dimensions: permitted materials (including steel with electro-deposited copper) and conductor cross-sections; revised cross-sectional requirements and guidance on minimum metal thicknesses.
• Separation distance: two simplified and detailed methods for evaluating separation distance between LPS conductors and exposed electrical equipment.
• Bonding & SPD use: guidance on bonding with isolating spark gaps for metal installations and using Surge Protective Devices (SPD) for internal systems.
• Inspection & maintenance: schedules, inspection order and maintenance practices for ensuring ongoing LPS effectiveness.
• Special cases: normative Annex D provides additional LPS information for structures with explosion risk; Annex E offers practical design and construction guidelines.

Applications and who uses it

IEC 62305-3 is used by:

• Lightning protection engineers and designers for LPS design and verification
• Electrical contractors and installers for correct installation of air‑terminations, down‑conductors and earthing
• Facility managers and building owners for risk assessment and maintenance planning
• Safety officers and inspectors ensuring compliance with national regulations and standards
• Plant designers in hazardous/explosive environments who need additional protection measures

Practical applications include protection of commercial and residential buildings, industrial plants, communication towers, substations, reinforced‑concrete structures and facilities with explosion risk.

Related standards

• IEC 62305-1: General principles (see for risk assessment methodology)
• IEC 62305-2: (storm and related topics)
• IEC 62305-4: (surge protection) Consult the IEC 62305 series for a complete, integrated approach to lightning risk management.

Keywords: IEC 62305-3, lightning protection, LPS design, touch and step voltages, air-termination, down-conductor, earthing, equipotential bonding, surge protective device, lightning protection standard.