Lightning surge protection is no longer just a recommendation for many buildings. Indeed, since the entry into force of the revised NF C 15-100 standard in August 2024 — applicable from September 1, 2025 — surge protection devices (SPDs) are now mandatory for several categories of installations internationally, and particularly in French-speaking countries applying this standard.
Therefore, understanding these new requirements is essential for any electrician, project owner, engineering firm, or property manager. Consequently, this article reviews the obligations, the types of SPDs concerned, and the solutions available for compliance.
The revised NF C 15-100 standard: what changes in 2024-2025
A continuously evolving reference framework
The NF C 15-100 standard has governed low-voltage electrical installations in France for several decades. It was substantially revised in August 2024, with a transition period and mandatory application from September 1, 2025.
Among the major changes in this revision, the regulations concerning surge protection devices (SPDs) — commonly known as surge arresters — are among the most significant. However, it is important to distinguish between situations where surge arresters are strictly mandatory and those where they remain strongly recommended.
Surge protector mandatory vs. strongly recommended
The NF C 15-100-1 standard (2024 edition) distinguishes between two situations:
- Regulatory requirement : surge protection is mandatory for certain specific categories of buildings, with no exceptions.
- Strongly recommended : for other buildings, the installation of a surge protector is recommended when the lightning strike density (Nsg) exceeds a local threshold or when sensitive equipment is present.
Which buildings are subject to the lightning protection requirement?
The service sector and specialized establishments
According to standard NF C 15-100-1 (August 2024), type 2 surge protectors are now mandatory for the following categories of new installations and extensions:
- Healthcare facilities (hospitals, clinics, nursing homes) — where the failure of medical equipment can be fatal
- public service and administrative buildings
- School and university buildings
- High-rise buildings (IGH)
- Buildings housing critical security systems (alarms, access control, video surveillance)
- photovoltaic installations Grid-connected or self-consumption
- Electric vehicle charging stations (EVCI)
In addition, multi-unit residential buildings with more than two dwellings are also subject to a main surge arrester requirement when the supply line is overhead or mixed — a common situation in rural areas and in many French-speaking countries in Africa and Latin America.
The specific case of photovoltaic installations
With the international growth of solar photovoltaics, protecting PV installations against lightning and power surges has become a major issue. In practical terms, an unprotected photovoltaic installation can be destroyed in microseconds by an induced power surge, even without a direct lightning strike.
Therefore, the standard now mandates SPDs on:
- The inverter's AC input (Type 2 minimum)
- The DC input on the panel side (specific DC SPD)
- Communications and dataloggers
Types of surge arresters according to IEC 62305-4 and NF C 15-100
SPD Type 1, Type 2, Type 3: the differences
The classification of SPDs into types 1, 2 and 3 corresponds to their ability to dissipate lightning energy:
- Type 1 : Intended for the building's main electrical panel (TGBT), it carries the largest lightning currents. Mandatory if the building is equipped with a lightning rod.
- Type 2 : installed in distribution boards, it protects against residual overvoltages. This is the type most commonly required by NF C 15-100.
- Type 3 : terminal protection as close as possible to sensitive equipment (surge protectors, DIN rail protection)
However, be aware: the types are not mutually exclusive. On the contrary, the coordination of Type 1 + Type 2 + Type 3 constitutes the optimal protection strategy according to IEC 62305-4 for buildings at risk.
Installation rules and coordination of SPDs
The effectiveness of a SPD depends on its correct sizing and installation. In particular, the length of the connecting wires must be minimized (ideally less than 50 cm) to avoid induced voltage drops that reduce protection.
Furthermore, the choice of the Up protection level (protection voltage) must be adapted to the shock resistance of the equipment to be protected. In addition, the coordination between the different SPD levels (Type 1, 2, and 3) must comply with the minimum distances prescribed by the standards.
Alert@ir DC: the connected surge protector for predictive maintenance
Beyond installation, SPD maintenance is a critical point that is often neglected. However, a tripped SPD (triggered cartridge or blown fuse) no longer protects the installation — without this being visually apparent, especially in electrical panels that are difficult to access.
That's why LPS France offers AlertAlert@ir DC : a connected monitoring device that continuously monitors the status of the SPDs and sends an automatic alert in case of a trigger. This way, you are informed immediately and can plan the replacement before the next storm season.
Manage your SPD compliance with LPS Manager
For building managers or multi-client installers, centralizing the monitoring of the status of all lightning protection devices (LPDs) is a major operational challenge. Ultimately, this is precisely what LPS Manager : a cloud platform that centralizes LPD alerts, intervention history, and IEC 62305 compliance reports for your entire lightning protection system.
Thus, once your SPDs are installed and comply with NF C 15-100, LPS Manager allows you to monitor them over time without additional effort.
Conclusion: Lightning protection becomes a legal obligation
In summary, the revision of NF C 15-100 marks a turning point: surge protection devices are no longer optional for a growing number of buildings. Therefore, building owners, architects, and electricians must integrate surge protection devices from the initial design of new installations or during extensions.
Furthermore, the quality of installation and maintenance makes all the difference between truly effective protection and equipment that gives a false sense of security. LPS France assists professionals in selecting, installing, and monitoring surge protection solutions for lightning strikes.
Need advice on your lightning protection obligations? Contact our team of experts LPS France — we'll guide you to the solution best suited to your building and regulatory context.
