Overview
IEC 62858:2019 - Lightning Density Based on Lightning Location Systems (LLS): General Principles is an international standard published by the International Electrotechnical Commission (IEC). This standard establishes the essential principles and methodologies to derive ground flash density (NG) and ground strike point density (NSG) values from lightning location systems in various countries. These parameters are fundamental for accurate lightning risk assessment, especially in the context of lightning protection of buildings, infrastructure, and critical installations.
The 2019 edition is a technical revision, superseding the 2015 edition, and introduces two new informative annexes on lightning density determination for risk calculation and ground strike point calculation methods.
Key Topics
- Lightning Location Systems (LLS): The standard focuses on utilizing data from LLS networks to obtain robust and homogeneous lightning density values. Critical LLS performance parameters such as detection efficiency, location accuracy, sensor sensitivity, and classification accuracy are addressed.
- Ground Flash Density (NG): Defined as the mean number of cloud-to-ground lightning flashes per unit area per year, NG is the principal input for lightning risk analysis.
- Ground Strike Point Density (NSG): Represents the mean number of distinct ground strike points per unit area per year, accounting for flashes with multiple ground contacts.
- Data Quality and Homogeneity: The standard outlines minimum requirements for data sample duration, grid cell size, network configuration, and correction methods to ensure comparability of lightning data on a national and international scale.
- Risk Assessment Relevance: Only those parameters necessary for lightning-related risk calculations are considered, in alignment with established lightning protection standards such as IEC 62305-2.
Applications
Practical uses of IEC 62858:2019 include:
- Lightning Protection Design: Engineers and consultants use NG and NSG data to calculate lightning risks and specify appropriate protection systems for structures.
- Infrastructure Planning: Utility companies, telecommunication providers, and operators of critical infrastructure rely on standardized lightning density data for asset protection, reliability improvements, and outage risk modeling.
- Insurance and Risk Management: Reliable lightning density values support actuarial analysis, facilitating accurate insurance risk assessment and policy development.
- Regulatory Compliance: The standard helps regulatory bodies ensure that lightning risk assessments and mitigation strategies are based on internationally harmonized, validated data.
Risk Calculation and Improvement
- NG and NSG values produced under IEC 62858 facilitate the implementation of lightning protection measures that are structurally and financially efficient.
- The improved methodology for determining ground strike points allows a more realistic evaluation of the lightning threat to assets.
Related Standards
- IEC 62305-1: Protection against lightning – Part 1: General principles
- Provides comprehensive principles of lightning protection.
- IEC 62305-2: Protection against lightning – Part 2: Risk management
- Details risk assessment methods referencing NG and NSG as core input parameters.
Additionally, the methodologies described in IEC 62858 are frequently cross-referenced in regional and national lightning protection standards, supporting harmonized risk assessment frameworks worldwide.
By following IEC 62858:2019, organizations and engineers can ensure that their use of lightning data-particularly NG and NSG-is internationally consistent, reliable, and fit for purpose in risk assessments. This enhances safety, facilitates compliance, and supports effective asset protection in the face of lightning hazards.