Every year, lightning causes numerous damages to industrial, commercial, and public buildings in France. To protect against it effectively, the early streamer emission (ESE) lightning rod remains the most widespread and efficient solution for direct lightning protection. This comprehensive guide explains how it works, the criteria for choosing the right one, the installation rules compliant with standard NF C 17-102:2011, and the maintenance requirements.
What is a ESE lightning rod?
An EFT (Early Flight Device) lightning rod is a lightning protection system that captures the lightning strike at a precise point and channels it to the ground via a down conductor, thus preventing the discharge from damaging the building structure or endangering its occupants.
Unlike a simple rod lightning rod (also known as a "passive point" lightning rod), which captures lightning solely through its height and the point effect, the ESE lightning rod incorporates an early streamer emission (ESE) device that triggers the corona effect earlier than the surrounding natural electric field. This early induction (denoted ΔT) allows the upward leader to be captured sooner than a simple rod, significantly increasing the protection radius covered by a single device.
This technology is particularly suited to buildings with a large footprint, industrial sites, public access buildings (ERP) and classified installations (ICPE) subject to an obligation of protection against lightning.
Operation and advantages of the ESE lightning rod
The operating principle of a ESE lightning rod is based on three elements: the capture tip, the triggering device (high voltage pulse generator) and the descent system connected to the ground.
When storm conditions create an intense electric field around the building, the triggering device emits an upward leader with a lead ΔT relative to a single point. This lead, expressed in microseconds, is measured in the laboratory according to a standardized test protocol and directly determines the device's protection radius
The protection radius (Rp) of a ESE lightning rod is calculated according to standard NF C 17-102:2011, based on three parameters:
- the height of the lightning rod above the plane to be protected (i.e. above the roof, and not the total height from the ground);
- the required level of protection (I, II, III or IV);
- the ignition advance ΔT of the device, expressed in microseconds.
The greater the ΔT advance and the higher the lightning rod is positioned above the roof, the greater the protection radius. This allows, in many cases, an entire building to be protected with a reduced number of devices, unlike a network of simple rods or meshed cages which requires more capture points.
The main advantages of the ESE lightning rod are therefore:
- a high protection radius for a limited number of devices;
- a discreet aesthetic integration into the roof;
- certification and laboratory testing according to the French standard NF C 17-102:2011;
- a proven solution, widely deployed across France for several decades.
How to choose your ESE lightning rod?
The choice of a lightning protection system (LPS) should never be improvised: it stems directly from a lightning risk analysis (LRA) and, depending on the building regulations, from a possible technical study. Several criteria must be taken into account:
1. The required level of protection
The NF C 17-102:2011 standard defines four levels of protection (I to IV), from the most demanding (level I) to the least demanding (level IV). This level is determined by the lightning risk analysis, which takes into account the building's activity, its occupancy, the presence of hazardous materials, and the local lightning density (Ng).
2. The height and configuration of the building
The height of the lightning rod above the roof (not the total height of the building from the ground) is the determining factor in calculating the effective protection radius. A complex roof, with multiple levels or superstructures (chimneys, air conditioning units, antennas), may require several lightning strike points.
3. The site environment
Local keraunic, presence of surrounding buildings, exposure to wind and corrosion (seaside, industrial environment) influence the choice of materials (stainless steel, copper) and model.
4. The ignition advance (ΔT)
Each ESE lightning rod model has a certified early flashover time, tested in an independent laboratory. This value, expressed in microseconds, directly determines the calculated protection radius according to NF C 17-102:2011.
LPS France designs and manufactures its own range Ellipsof ESE lightning rods certified to the NF C 17-102:2011 standard, available with different early-flash lead times to suit project requirements. Browse our complete range of ESE lightning rods to compare available models based on your protection level and building configuration.
Installation compliant with NF C 17-102:2011
The installation of a ESE lightning rod must absolutely comply with the requirements of the standard NF C 17-102:2011, which governs the sizing, implementation and testing of the lightning protection system in France.
Mast height
The lightning protection system (LPS) must be installed at least 2 meters above the structure to be protected (i.e., above the roof, not the total height from the ground). This is why the use of extension masts is essential: LPS France offers extension masts from 1 to 6 meters, allowing the LPS to be positioned at the optimal height according to the desired protection radius and the building's configuration.
Grounding conductors
The captured lightning current is carried to earth by one or more down conductors, the number of which depends on the level of protection and the height of the building. These conductors must follow the shortest and straightest path possible, avoiding sharp angles.
Grounding and metering point
Each down conductor terminates at a dedicated earth electrode, the resistance of which must comply with the standard requirements. A metering point (inspection chamber) is installed on each down conductor to allow for periodic checking of electrical continuity and earth resistance.
Complementarity with surge protection
The international standard IEC 62305:2024 complements direct protection systems by addressing surge protection (surge arresters) that protect electrical and electronic equipment from the indirect effects of lightning. A ESE lightning protection system compliant with NF C 17-102:2011 benefits from being supplemented with complete lightning protection kits that include all the necessary components (mast, conductors, mastheads, control joints, grounding connections) for a turnkey installation.
ESE lightning rod maintenance and verification
A ESE lightning rod is not a "one-time installation": the NF C 17-102:2011 standard mandates a periodic verification program to guarantee its proper long-term operation. As the ESE lightning rod is a critical protection system, a complete verification is required annually.
- Annual visual inspection : general condition of the capture device, down conductors, fixings and counting points.
- Annual full verification : measurement of earth resistance and check of electrical continuity of the entire installation.
- Post-lightning strike verification : systematic after any confirmed lightning strike, to ensure that the installation has not suffered any damage compromising its effectiveness.
It is precisely to reduce the burden associated with these checks that the installation of a lightning strike counter on the down conductors is strongly recommended. Thanks to the counter, it is possible to know remotely whether the lightning rod has been activated, without having to go up onto the roof after every storm or every year for a simple visual inspection. It is an essential piece of equipment on any sensitive site.
These checks, carried out by a qualified professional, must be the subject of a written report kept in the installation's logbook, a document required during regulatory checks.
Why choose LPS France ?
LPS France is a French manufacturer specializing in the design and manufacture of lightning protection systems. We offer a complete range of ESE lightning rods certified to the NF C 17-102:2011 standard, including our Ellips, as well as the Paraton@ir, to meet all direct lightning protection needs.
Beyond manufacturing, LPS France supports design offices, installers and project owners with dedicated technical support, and provides LPS Manager, an application dedicated to sizing lightning protection installations according to NF C 17-102:2011 and IEC 62305:2024, facilitating the calculation of the protection radius and the choice of the model adapted to each project.
Whether you are an installer, design office or project owner, our team remains at your disposal to assist you in the choice, sizing and installation of your ESE lightning rod.
Frequently Asked Questions
What is the difference between a ESE lightning rod and a simple rod lightning rod?
A simple rod lightning rod captures lightning solely due to its height and the natural point effect. The ESE lightning rod incorporates an early streamer emission (ESE) device that triggers the upward leader (ΔT) in advance, thus increasing its protection radius compared to a simple rod of the same height.
What mast height should I choose for a ESE lightning rod?
The tip of the ESE lightning rod must be at least 2 meters above the structure to be protected (measured above the roof, not from the ground). Extension masts ranging from 1 to 6 meters in height allow the desired protection radius to be adjusted. The taller the mast, the greater the protection radius.
How often should a ESE lightning rod be checked?
The NF C 17-102:2011 standard mandates a comprehensive annual verification for critical protection systems such as ESE lightning rods, including a visual inspection and earth resistance measurement. A further verification is systematically required after any confirmed lightning strike. Installing a lightning strike counter can reduce these interventions by detecting strikes remotely.
What standard governs the installation of a ESE lightning rod in France?
The installation of a ESE lightning rod in France is governed by the French standard NF C 17-102:2011, supplemented where appropriate by the international standard IEC 62305:2024 for protection against overvoltages and indirect effects of lightning.
