Lightning protection is a major concern for the safety of people, the protection of infrastructure, and the continuity of electrical and electronic installations. In 2024, the International Electrotechnical Commission published a complete revision of the IEC 62305 . This new version includes significant technical improvements compared to the 2010 edition.
This update modernizes lightning risk management , clarifies design points (physical protection, separation distances, components) and strengthens the "systems" approach (surge arresters, electromagnetic compatibility, LEMP). Two concepts become particularly prominent in practice: NSG (lightning data for risk analysis) and Thunderstorm Warning System – TWS .
What is the IEC 62305 standard?
IEC 62305 series is a four-part international standard that defines the principles, risk management, physical protection, and protection of electrical systems against lightning. It applies to the design, installation, inspection, and maintenance of lightning protection systems ( LPS ) for structures and their contents.
- IEC 62305-1 : General principles
- IEC 62305-2 : Risk analysis and management
- IEC 62305-3 : Physical protection of structures
- IEC 62305-4 : Protection of electrical/electronic systems (LEMP)
IEC 62305:2024 — main new features
1) A more modern risk analysis (IEC 62305-2:2024)
Part IEC 62305-2:2024 , dedicated to risk assessment, introduces significant conceptual changes to better reflect current realities (connected buildings, critical systems, availability requirements).
What's changing:
- Unified risk : From now on, a more comprehensive approach combining, in particular, human losses and material losses related to fires, for a more coherent understanding of the danger.
- Frequency of damage : thus, frequency is taken into account more to measure the impact on the availability of internal systems (e.g. critical systems, computer networks, automation).
- NSG replaces NG : indeed, the density of ground impact points (NSG) replaces the old lightning strike density (NG) to more accurately estimate the number of foreseeable hazardous events.
- Recognition of TWS : Overall, Thunderstorm Warning Systems (TWS) compliant with the IEC 62793 are now recognized as a temporary risk reduction measure.
These developments allow for a more precise and realistic assessment, facilitating the sizing of appropriate protections.
NSG (IEC 62305-2:2024): definition and practical relevance
The NSG ( Net Ground Safety) is used to improve the representativeness of ground impacts in risk calculations. Indeed, the goal is not simply to "find a value," but to be able to document a consistent methodology (scope, time period, assumptions). This will provide usable data for single or multiple sites.
To go further (data & reporting approach): lightning data solutions can help produce indicators and reports useful to the process. For example, StrikeRadar is a cloud-to-ground data-oriented solution. Thanks to its multi-site management and PDF reports (incidence, keraunic, etc.), it can support the technical justification of a risk analysis.
2) Components and physical protection: greater precision (IEC 62305-1 & IEC 62305-3)
Parts IEC 62305-1:2024 and IEC 62305-3:2024 also introduce important technical changes.
IEC 62305-1:2024 — general principles
- Introduction of references to the IEC 62561 in order to harmonize LPS components with product and testing requirements.
- Increased accuracy of storm currents used for sizing, particularly useful for the consistency of protection choices.
IEC 62305-3:2024 — physical protection
- New requirements on the minimum thickness of certain metallic conductors to limit the risks of hot spots under impact.
- Clarification of methods for calculating separation distances to reduce risks related to induced overvoltages.
- Guidance on modern cases (e.g., green roofs , projecting facade elements), in line with current architectural practices.
3) Protection of electrical and electronic systems (IEC 62305-4:2024)
Part IEC 62305-4:2024 focuses on the protection of electrical and electronic installations against the effects of lightning-related electromagnetic pulses ( LEMP ). It includes annexes and additional test methods to assess system-level behavior, a particularly important point for sensitive installations (data centers, industrial networks, telecommunications).
TWS (IEC 62793): a recognized measure… if it is operational
The integration of TWS into IEC 62305-2:2024 is a strong signal: prevention and HSE organization matter, in addition to physical protections.
In practice, a useful TWS should enable the following:
- trigger alerts at the right time,
- inform the people concerned,
- track the execution of instructions (HSE audit, internal compliance),
- and demonstrate the correct application of procedures.
To go further (rapid deployment and operational management): solutions like Sky Sentinel are designed for deployment in minutes, without on-site equipment, with multi-level alerts and operational monitoring.
Why is this review important?
A standard more aligned with modern risks
The 2024 edition better reflects the realities of complex and connected installations by incorporating:
- proactive prevention measures (TWS),
- a more comprehensive view of risk,
- and more precise calculation methods (including NSG).
Transition to compliance
Depending on national, contractual or insurance frameworks, the 2010 edition may remain in use during a transition period, but the 2024 edition is gradually becoming the expected reference for new projects.
Summary table: IEC 62305 (2010) vs IEC 62305 (2024)
| Subject | 2010 Edition | 2024 Edition |
|---|---|---|
| Risk method | Separate categories | A more unified vision |
| Lightning data | NG | NSG |
| Alert systems | Not recognized | Integrated TWS (IEC 62793) |
| LPS Components | Less harmonized guidance | Reinforced references IEC 62561 |
| Modern practices | Limited coverage | Expanded guidance (green roofs, facades, etc.) |
FAQ — IEC 62305:2024, NSG and TWS
Does NSG officially replace NG in IEC 62305-2:2024?
Yes, the 2024 edition introduces NSG as a reference data to better represent ground impact points.
How to obtain an NSG value for a lightning risk analysis?
This depends on the data sources and the scope of the study (single site, multiple sites, radius, area). The important thing is to be able to justify the method and maintain traceability of the assumptions.
Is a TWS recognized by the IEC 62305 standard?
Yes, IEC 62305-2:2024 recognizes TWS compliant with IEC 62793 as a temporary risk reduction measure.
Does a TWS replace an LPS (collection, descents, ground)?
No. A TWS is an organizational/temporary measure. It does not replace physical protection or the protection of internal systems.
Conclusion
IEC 62305:2024 standard significantly modernizes the way lightning protection is assessed and designed: more robust risk analysis, better consideration of internal systems, and recognition of prevention tools such as TWS ( Systems). For professionals (engineers, design offices, installers, HSE), it is an essential foundation for improving safety and business continuity.
If you are working on an IEC 62305-2:2024 risk analysis , two points often become central:
- to have usable indicators for the NSG (e.g., via a data approach like StrikeRadar ),
- and to set up a TWS (e.g., Sky Sentinel ).