IEC 62305 in plain English
Guides to the lightning protection standard, the risk method behind every assessment, and how Lumex turns it into a report you can defend.
Lightning protection risk assessment
What the assessment decides, who it applies to, where its input numbers come from, and what a report needs to contain to survive review.
What is IEC 62305?
The international lightning protection standard, its four parts, who needs it, and what the 2024 third edition changed.
What is a lightning protection system?
The complete LPS: its external and internal parts, the components, the four LPS classes, and how IEC 62305 specifies one from risk.
The IEC 62305-2 risk method
How the risk of injury to people R and the frequency of damage F, and the nine risk components, are computed and compared against the tolerable values.
How an IEC 62305 risk is calculated
A plain-English worked walkthrough of one risk calculation, from the inputs to the pass or fail verdict, on an example building.
Lightning protection levels (LPL I-IV)
What LPL I to IV mean, how the risk assessment decides the level, and how it maps to the LPS class.
Air-termination methods
The rolling sphere, mesh and protection angle methods for positioning lightning air terminations under IEC 62305-3.
Rolling sphere calculator
A free calculator that estimates the protected ground radius of a single vertical mast using rolling sphere geometry.
Lightning protection zones (LPZ)
How IEC 62305 zones step the threat down from outside to equipment, plus the separation distance and bonding.
Earthing & the earth termination
How the earth-termination system dissipates a strike, its Type A and Type B electrodes, and why earthing is inspected.
What changed in IEC 62305:2024
Every third-edition change explained one by one, from the density term to warning system credit, and why the edition you compute on is part of the verdict.
IEC 62305-3 inspection & testing
The periodic LPS inspection for the maintenance cycle: what is checked, how often, and what the report records.
SPD Types 1, 2 and 3 explained
Surge protective devices under IEC 62305: the lightning protection zones, coordinated protection, and how SPDs cut internal-failure risk.
ESE air terminals and IEC 62305
IEC 62305 specifies conventional air terminations, not ESE devices; the ESE method lives in NF C 17-102, a separate national standard.
Traceable, not AI-generated
Why IEC 62305 risk figures must be calculated and traceable to their inputs, never produced by a language model.
Audit-ready risk reports
What an auditor, insurer or authority actually needs to see in an IEC 62305 risk assessment report.
IEC 62305 around the world
How IEC 62305 is adopted as a national standard, often word for word, across most of the world, and where the US differs.
BS EN 62305 in the UK
What the British Standard is, how it relates to the IEC original, what the national annexes add, and what the March 2025 corrigendum changed.
Risk assessment for data centres
Why data centres are an extreme IEC 62305 case where continuity of service, not the building, drives the risk.
Risk assessment for hospitals
Why hospitals carry exceptional life-safety risk under IEC 62305 and how a healthcare campus is modelled.
Lightning protection for telecom
Why telecom towers are struck so often, and how IEC 62305 protects the electronics that keep a network on the air.
Protection for heritage buildings
Why irreplaceable historic buildings need IEC 62305 protection, and how to fit it without harming the fabric.
Oil, gas & hazardous sites
Why a flammable atmosphere makes lightning a high-consequence threat, and how IEC 62305 controls it.
Risk assessment for renewable energy
Why solar farms, wind sites and substations need an IEC 62305 assessment, and what makes them different to model.
NFPA 780 vs IEC 62305
The two main lightning standards side by side: where each applies, how the risk methods differ, and which to use.
Lightning protection system design
The IEC 62305 design sequence in order, from the risk assessment that sets the class through to the deliverable, with a worked example.
Lightning risk assessment software
The IEC 62305 tools engineers use, compared on the things that decide an audit: edition, traceability, output and price.
A Furse StrikeRisk alternative
What ABB publishes about StrikeRisk, what a browser tool on the 2024 edition changes, and where StrikeRisk still wins.
A DEHN Risk Tool alternative
The DEHNsupport Toolbox and DEHNrisk are two different products on two different editions. Which one you have decides the rest.
IEC 62305 in Germany
Germany's recorded departure: r_p = 1 for all cases, so fire provisions earn no reduction in P_B or P_V.
IEC 62305 in Greece
Greece's recorded departure: P_TWS = 1 for all cases, so a thunderstorm warning system earns no reduction in six components.
IEC 62305 in Italy
Italy compares R_L1 and R_L2 with the tolerable risk separately, rather than their sum, and that is more permissive.
Annex D and Annex E in national practice
The Netherlands and South Africa do not apply Annex D or Annex E for usual studies. What each annex contributes.
SS 555 in Singapore
Part 2 is identical to IEC 62305-2:2010 and Part 1 is modified. The four Annex ZA deviations, and the Class III floor the risk assessment cannot go below.
CTE DB SUA 8 in Spain
Spain's building code decides the protection question with its own Ne and Na formulas. IEC 62305 is not cited anywhere in the Documento Basico.
MS IEC 62305 in Malaysia
Enforced under the Electricity Supply Act with a criminal penalty, phased across existing buildings from 2021, and mandated on the 2006 first edition.
Want to see the method run end to end? Read how an IEC 62305 assessment works, clause by clause.
Lumex computes the IEC 62305-2 method and shows the working. It does not certify a structure. You may not issue or submit a Lumex output until a competent person, qualified where the structure is located, has reviewed the inputs and the result and signed it.
The tolerable risk in IEC 62305-2 is not a fixed constant. Clause 7.3 NOTE 1 gives RT = 1×10-5 per year as a representative value of tolerable risk and adds that another value may be set once the case has been investigated in detail. Printed p.12 then lets national or local regulations fix RT, the tolerable frequency of damage FT, and the Annex A, B, C and E calculation rules and parameter values. Every Lumex assessment states the jurisdiction it was computed under and the values that applied.