Direct and indirect effects protection

Systems of protection direct effects

meshed cage INSTALLATIONS 

The protection by meshed cage consists in the installation, on the surface of a building, of a Faraday cage with large meshes, connected to the ground earthing systems. Points with low dimensions (0.5 meters), named strike points, are arranged on any summit (chimneys, shelters,…). The dimension of the meshes and the distance between any 2 down conductors
correspond to the level of protection needed to comply with the NF C 17-100 standard.

tight strand

This system consists in the protection of a structure without touching it. This protection is most often used if dangerous products are stored in the structure.
This system requires the installation of guyed towers to sustain the cables and as many earthing systems as necessary.


simple rod

Known also as a simple lightning rod Franklin type, its installation consists in the inclusion, on the top of the structure to protect, slender points connected to the earth by the most direct path possible.
A cone of protection is produced which corresponds to the height of the rod and to the level of protection required. Contrary to the meshed cage, this method only protects the elements which are in its radius of protection.

early streamer emission lightning conductor

The principle of the Early Streamer Emission lightning conductor consists in equipping a simple rod with a device which allows a reduction of the excitation time.
The radius of protection proposed by this type of lightning conductor is then widely superior to a simple rod, it can even reach 120 m in level III.


The guiding principle of an Early Streamer Emission (ESE) Lightning conductor rises from an experimental observation. While simulating, in a high voltage laboratory, a range of electric discharges “lightning” on a simple rod (Franklin type), one notes that the excitation times are distributed graphically in a ramdom way, with a certain standard deviation, around an average value TSR.
The guiding principle of an ESE Lightning conductor consists in equipping a simple rod with a device allowing for one part to reduce the average value of excitation times TESE < TSR and in addition to attenuate their standard deviation.
That means that, placed under the same conditions, in particular, when they have the same height and the same geometrical form, the start of the discharge for an ESE Lightning conductor (ascending tracer) occurs earlier than with a simple rod, with an increase in effective length ΔL, it thus has a better probability of capturing the tracer going down and of flowing the current of the lightning.  


Share this page on :

Other documents

Lightning risk assessment

Lightning density

Lightning risk assessment

Deterministic method

Lightning risk assessment

Complete probabilistic method

Lightning phenomenon

Applicable standards and rules

Direct and indirect effects protection

Protection against indirect effects

Lightning phenomenon

Devastating effects of lightning

Lightning phenomenon

Stormy cloud creation