The different types of lightning rods: how to choose the right lightning protection?
Lightning releases up to 200,000 amps in a fraction of a second. In France, even though the lightning strike risk varies by region, lightning rods adapted to each situation help reduce this real risk to structures and equipment. For Public Access Buildings (ERP) and Classified Installations (ICPE), appropriate protection is often a regulatory requirement.
At LPS France, a subsidiary of GROUPE CEMASO SAS, we leverage over 10 years of experience in lightning protection to ensure the safety of property and people. Our expertise covers Lightning Risk Analysis (LRA) and technical studies to determine the level of protection (I to IV) required by the NF C 17-102 standard.
What is a lightning rod and what is its fundamental role?
A lightning rod is the central element of an External Lightning Protection System (ELPS). Its function is to capture the direct lightning strike to prevent random impact on the structure, then channel this destructive electrical current to the ground.
Regardless of the type of lightning rod chosen, the system relies on three inseparable components:
- The capture device: a point at the top of the building intercepting the electric arc.
- Down conductors: metallic cables (copper or aluminum) connecting the capture to the ground, fixed to resist electrodynamic forces.
- The grounding connection: it disperses energy into the ground. Its resistance must be less than 10 Ohms (NF C 17-100 standard).
Without effective grounding and equipotentiality of metallic masses, the device remains inoperative.
Type 1 — The simple pointed lightning rod (Franklin): the historically proven solution
Invented by Benjamin Franklin , the single-point lightning rod (SPR) represents the oldest technology. This tapered metal rod, placed on high points, functions passively while waiting for an updraft leader to meet the downdraft leader of the cloud.
Its effectiveness is limited to a conical volume (angle of approximately 45°). To protect large buildings, multiple points must be used and connected to form a mesh cage (Faraday cage).
Technical characteristics of a meshed cage:
- Grid size: from 5×5 meters (Level I) to 20×20 meters (Level IV).
- Capture points: short spikes around the perimeter of the roof.
- Descents: one every 10 to 20 meters.
Although effective for electromagnetic compatibility, this type of lightning rod remains cumbersome to implement, expensive in terms of materials and not very aesthetically pleasing.
Type 2 — Early streamer emission (ESE) lightning rod: French innovation for efficiency
The Early Streamer Emission (ESE) lightning rod is an active technology designed to generate an upward leader earlier than a simple tip (early initiation in µs). This time saving allows lightning to be captured at a greater distance, providing a significantly extended protection radius.
Comparison of lightning rod types: protection radius (Height 5m, Level I)
| Lightning rod type | Technology | Approximate protection radius. | Main advantage |
|---|---|---|---|
| Simple point (Franklin) | Passive | ~ 5 to 7 meters | Mechanical simplicity |
| ESE (Advance 60µs) | Active | ~ 79 meters | Large coverage area |
Our ELLIPS and PARATON@IR exemplify this French innovation. Compliant with the NF C 17-102 standard and laboratory tested (with a lead time of 10µs to 60µs), these PDA lightning rods ensure optimal safety. The ELLIPS uses a reliable spark gap triggering system, while the PARATON@IR incorporates advanced communication technology. A single PDA often protects a complex site, reducing overall cost (fewer down conductors and grounding connections) while maintaining aesthetics.
Type 3 — Radioactive lightning rods: a technology abandoned for good reasons
Radioactive lightning rods, using sources such as Radium-226 or Americium-241, are an obsolete technology. Their superior effectiveness against health and environmental risks has never been demonstrated. In France, a decree of October 11, 1983, prohibited their sale, followed by a mandatory removal order in 2008.
The risks are numerous: dispersal of radioactive elements in case of destruction and exposure to ionizing radiation. Dismantling, strictly regulated by ANDRA, must be carried out by specialists. Replacement with a ESE or a simple probe is mandatory.
Other complementary systems: surge arresters and monitoring for comprehensive lightning protection
Protection against direct impact is not sufficient. Surge arresters (main distribution boards) are essential to counteract transient overvoltages carried by the power grid:
- Type 1: discharges a direct lightning current (10/350 µs wave).
- Type 2: protects against induced overvoltages (8/20 µs wave).
- Type 3: thin protection of sensitive equipment.
For maintenance, our Contact@ir revolutionizes installation monitoring. This IoT solution allows you to remotely monitor the status of your lightning protection in real time. It sends an immediate alert in the event of a lightning strike, indicating the intensity and time. This allows you to verify operation without unnecessary travel and ensure continuous compliance.
How to choose the right type of lightning rod for your building?
The choice between a simple point, a meshed cage, or an Early Streamer Emission (ESE) lightning rod depends on the building's architecture, risk analysis, and budget. While the Franklin point remains a historical choice, ESEs offer broad coverage and simplified installation, making them ideal for industrial sites.
The quality of the equipment is non-negotiable. Choosing LPS France means opting for French manufacturing, guaranteeing complete control of the value chain . This traceability ensures compliance with standards (NF C 17-102, IEC 62305) and durability against corrosion. Lightning protection is an investment that demands technical excellence.
Frequently asked questions about types of lightning rods
What are the different types of lightning rods that exist?
There are three main types: the passive simple point (Franklin), the meshed cage (Faraday) and the Early Streamer Emission (ESE) Lightning Rod, an active technology with an extended protection radius.
What is the best type of lightning rod for my building?
It all depends on the Lightning Risk Analysis (LRA). The ESE is often preferred for large sites or complex buildings due to its wide protection radius and less invasive installation.
How exactly does a simple pointed lightning rod work?
It creates a preferential point of impact thanks to its high position, capturing the downward leader of the lightning to conduct the electrical current to the ground via conductors.
What is the difference between a lightning rod and a surge protector?
The lightning rod protects the structure against direct impact (fire, destruction), while the surge protector protects internal electrical equipment against overvoltages carried by cables.