IEC 62305-2:2024

Overview

IEC 62305-2:2024 is the third edition of the international standard published by the International Electrotechnical Commission (IEC) that focuses on protection against lightning through risk management. This part of the IEC 62305 series provides structured procedures to evaluate the risk posed by lightning flashes to earth affecting structures. Its main goal is to assist in selecting appropriate protection measures to reduce the lightning risk to or below a pre-established tolerable limit.

This 2024 edition replaces the 2010 second edition and introduces technical revisions, including new concepts such as combining human life loss and fire damage into a single risk, assessing the frequency of damage impairing internal systems’ availability, and utilizing lightning ground strike-point density for risk evaluation.

Key Topics

• Risk Management Procedure: The standard outlines a detailed procedure for risk evaluation, including assessing potential damage sources, types of loss, and risk components relevant to a structure exposed to lightning.

• Risk Components and Damage Sources: Four primary sources of damage (S1 to S4) are analyzed in the context of the structure and its environments:

  • Direct lightning strikes to the structure
  • Strikes to nearby structures or lines
  • Strikes near lines impacting internal system availability
  • Secondary effects such as fire or explosion caused by lightning

• New Concepts in Risk Assessment:

  • Single Risk Concept: Combines losses of human life and fire damage for comprehensive risk evaluation.
  • Frequency of Damage: Focus on how often lightning damage can impair the structure’s internal systems.
  • Ground Strike-Point Density (NSG): Replaces previous lightning flash density (NG) data to improve accuracy in estimating dangerous event occurrences.
  • Preventive Temporary Measures: Incorporation of thunderstorm warning systems (TWS) compliant with IEC 62793 to temporarily reduce certain risk components, including risk of direct strikes in open areas.

• Partitioning for Detailed Risk Evaluation: Structures can be divided into risk zones and lines into sections to assess risk components with greater precision.

• Calculation of Loss and Probability: The standard provides guidance on estimating the probability of damage, expected losses, and frequency of dangerous events using comprehensive models described in informative annexes.

Applications

IEC 62305-2:2024 is critical for professionals engaged in:

• Lightning Protection System Design: Electrical engineers and safety specialists can leverage the risk management procedures to design and specify lightning protection measures optimized for safety and cost-effectiveness.
• Risk Assessment for Structures: Owners and facility managers of buildings, including houses, offices, hospitals, and industrial facilities, can evaluate their lightning risk status and mitigate threats to life, property, and system availability.
• Development of Safety Protocols: Organizations can integrate preventive temporary measures, such as TWS, into their safety policies to further minimize lightning risks during severe weather events.
• Standard Compliance and Certification: Ensures adherence to international standards in lightning protection and risk mitigation, facilitating regulatory approval and insurance requirements.

Related Standards

• IEC 62305-1, 3, and 4: Complementary parts covering general principles, physical damage to structures and life hazard, and electrical and electronic system protection respectively.
• IEC 62793: Specifies requirements for thunderstorm warning systems (TWS) used as preventive temporary lightning risk reduction measures.
• National and Regional Lightning Protection Codes: Local standards often reference IEC 62305 series for harmonized lightning risk management approaches.

Adopting IEC 62305-2:2024 supports comprehensive lightning risk management by delivering a technically updated framework for assessing, quantifying, and reducing risks, thereby enhancing protection of human life, structural integrity, and system functionality from lightning hazards. This makes it an indispensable resource for engineering, safety, and risk professionals worldwide.