Across industrial sites worldwide, a single ground strike can halt production lines, ignite volatile atmospheres, and expose operators to lethal voltages. According to Météo-France’s 2025 assessment, France alone records roughly 1 million lightning strikes per year. For a safety manager responsible for chemical storage, pharmaceutical batch processes, or energy infrastructure, those numbers translate directly into risk-management decisions that cannot be deferred.
Three priorities before you assess your site’s exposure:
- Verify whether your installation qualifies as an ICPE subject to the compulsory lightning-risk study imposed by French regulations.
- Identify the local ground flash density for your geographic zone — it is the foundation of every sizing calculation.
- Distinguish between structural lightning protection (direct strike) and surge protection (conducted and induced overvoltages): both are mandatory, and neither replaces the other.
What follows is a structured reading of the technical and regulatory framework that governs lightning protection for industrial facilities. The objective is to give you the vocabulary and the analytical grid you need to evaluate a protection study, challenge a contractor’s proposal, or brief an internal task force — without getting lost in the normative labyrinth.
The article covers the physical threat, the applicable international standards, the French regulatory layer specific to classified installations, the architecture of a complete protection system, and the role of real-time thunderstorm warning in operational safety.
How lightning actually threatens an industrial site
The standard mental image — a bolt striking a chimney stack — captures only a fraction of the real threat. A lightning channel dissipates between 1 and 20 gigajoules of energy in a few microseconds, and the consequences for an industrial site unfold along two distinct pathways that demand separate engineering responses.
The first pathway is the direct strike. When a channel terminates on a structure, the return current — typically 30 kA but reaching 200 kA in exceptional events — flows through the building fabric. Structural damage, fire, and immediate electrocution risk are the obvious consequences. Less obvious is the partial flow through earthing networks and cable shields, which can reach instrumentation rooms located tens of metres from the strike point.
The second pathway is conducted and induced overvoltage. A strike to the ground within 500 metres of a facility couples electromagnetically with power lines, control cables, and metallic pipe runs. The resulting transient — potentially several kilovolts — propagates into PLCs, variable-speed drives, pressure transmitters, and any other electronics connected to the affected conductors. The practical experience of sites in the petrochemical sector shows that the majority of lightning-related production stops are attributable to this secondary mechanism, not to direct strikes.
1 000 000
impacts/an
Nombre estimé d’impacts de foudre au sol recensés chaque année en France métropolitaine
A third, often underestimated, threat is the step voltage generated when current spreads radially through the soil from a strike point. Personnel working in open areas — loading docks, tank farms, outdoor maintenance zones — are at risk from potential differences across the span of a normal stride. This mechanism is responsible for a significant share of the 1 to 2 fatalities recorded annually in France, as documented by Météo-France.
Understanding these three pathways is not academic: each drives a distinct set of design measures. Confusing them — or addressing only one — is the most common and costly mistake observed during post-incident investigations on industrial sites.
The specific exposure of a given site depends on two computable variables: the local ground flash density (GFD), expressed in flashes per square kilometre per year, and the effective collection area of each structure. Both feed directly into the risk calculation defined by the IEC standards. For industries operating across multiple geographic locations, this calculation can yield strikingly different results from one site to another — a fact that argues against applying a uniform corporate protection standard without site-specific verification. Platforms specialising in lightning protection for industrial plants aggregate historical strike density data at the spatial resolution needed to perform this calculation reliably.
IEC 62858 and IEC 62793: the normative backbone
Two IEC standards frame the technical design of industrial lightning protection systems. Knowing their scope prevents the frequent error of applying the wrong normative layer to a given problem.
IEC 62858 governs the measurement and characterisation of lightning ground flash density. It standardises how detection networks record strike events, how data quality is assessed, and — critically — how GFD values are to be used in risk calculations according to IEC 62305. For a site engineer, the practical implication is clear: a GFD figure is only usable as a design input if it has been produced by a network compliant with this standard. Using a GFD estimate derived from outdated climatological tables — a practice still encountered in some legacy risk studies — leads to systematic undersizing of protection levels in regions with high convective activity.
IEC 62793:2022 addresses a different but complementary dimension: the thunderstorm warning system. As specified in its scope, this standard establishes requirements for systems designed to detect the approach of an electrical storm and trigger safety protocols before the first strike occurs. The critical word is