Lightning is a powerful natural phenomenon that can cause significant damage to electrical installations. To prevent damage caused by power surges, it is crucial to install surge protectors correctly. This guide provides an overview of best practices for lightning protection, according to NF C 15-100 and C15-443 standards.
Basic Principles of Surge Protectors
Surge protectors are devices installed in electrical systems to protect equipment from transient overvoltages caused by lightning. They work by diverting the surge to the ground, thus protecting the connected devices.
Types of Surge Protectors and Their Placement
Primary Surge Protectors (Type I):
- Placement: Installed upstream in the internal distribution, typically at the main low-voltage switchboard (TGBT).
- Purpose: Prevent disruptive currents from entering the installation.
Secondary Surge Protectors (Types II and III):
- Placement: Installed near the equipment to be protected.
- Purpose: Prevent conductors between surge protectors and equipment from being disrupted again by induced effects.
Rules for Installing Surge Protectors
Cable Length
The total length of cables between surge protectors and equipment should not exceed 50 cm (L1+L2+L3 < 50 cm). The formula U=L⋅didtU = L \cdot \frac{di}{dt}U=L⋅dtdi is used to calculate the voltage in the cables, where excessive length can dangerously increase this voltage.
Cable Separation
It is crucial to separate incoming cables (from the network) and outgoing cables (to the installation). Additionally, phase, neutral, and PE cables should be grouped on the same side of the panel to reduce the loop surface area.
Distance Between Primary and Secondary Surge Protectors
The distance between a primary and secondary surge protector is determined by the protection levels Up1Up1Up1 and Up2Up2Up2 of the respective surge protectors.
Distance Between Surge Protectors and Equipment
The length between the surge protector and the equipment should not exceed 30 m. If this distance is greater, another surge protector should be installed near the equipment to prevent destructive voltage oscillations.
Installing Surge Protectors in Various Scenarios
Buildings with Lightning Rods:
If a lightning rod is installed on Building A and the distance to Building B is less than 50 m, a Type 1 surge protector should also be installed in Building B.
Overhead Network:
For installations with an overhead network between two buildings, a Type 1 surge protector should be installed in each connected building.
Grounding
The rules for installing surge protectors state that the installation of a surge protector does not require a specific grounding resistance. Values compliant with NF C 15-100 standards are sufficient. However, for installations with a lightning rod, the grounding resistance should be 10 ohms or less.
Interconnecting Grounding Systems
All grounding systems in the same building must be interconnected for optimal protection. Additionally, for installations serving multiple buildings, it is recommended to interconnect the grounding systems of each building if the distance is short.
Discover the Surtelec Range of Surge Protectors
At Optim-Elec, we distribute a wide range of surge protectors from the Surtelec brand, renowned for its reliability and exceptional performance. Surtelec surge protectors provide optimal protection for your electrical installations, whether primary or secondary surge protectors.
--> Discover our Surtelec products.
Contact Us
For any questions or to receive personalized assistance on protecting your electrical installations from lightning, do not hesitate to contact our team. We are here to help you choose the best solutions tailored to your specific needs.
