Did you know ?

1. Schools : Did you know that your children are not protected ?

In many countries (France, Portugal, etc.) there are at present no regulations requiring schools to install lightning protection, or even to evaluate the risk! Other countries (Germany, Spain, etc.), aware of the risk and relatively low cost of installing lightning protection, have already taken appropriate measures.
It is not however due to the lack of examples of accidents and incidents :
  • Saix primary and nursery school near Toulouse (15 January 1998): Lightning strike on the roof causing a major fire
  • Félix Gouin primary school at Istres: Lightning strike in the playground
  • Joncquière nursery school at Fos sur Mer: Lightning strike in the playground

    • How many more accidents must there be before action is taken ?

    2. Radioactivity
    Did you know that almost 40,000 radioactive lightning conductors are still installed on French roofs?

    Their sale and installation has been banned since 1996. Before this date, radioactive lightning conductors were widely used as elements for lightning protection as their technology at the time was the most appropriate. Contrary to Spain and England, who took the necessary measures to remove these radioactive lightning conductors as soon as they were banned, there is no regulation in France requiring industrials and administrations to remove them. Storage solutions, under ANDRA's (National Agency for the Management of Radioactive Waste) control, for this type of radioactive waste are now operational.

     

    3. Protection by natural components

    Natural components of the structure are too often incorrectly used as protection elements :
    En effet :
  • Networks at the bottom of excavations are all too often used for earth rods ;
  • Minimum roof thicknesses are too commonly ignored (3 mm for areas where a fusion point is unacceptable);
  • Pylons are too rarely fitted with a dedicated earth rod, albeit a must;
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    FAQ

    - Are tests carried out in laboratories on early streamer emission lightning conductors transposable to natural sites ?

    Current recordings were taken in different conditions: in the laboratory, in-situ – provoked strikes and in-situ – natural strikes. They show similar forms thus proving the likeness of the phenomena.

    - Does the tracer speed influence protection radii ?

    The speed of the falling tracer is defined in NF C 17-102. These values are based on in-situ scientific studies. The protection radius is dependent on this speed. Experience of real protection zones observed in the field confirms the validity of the model and the adopted tracer speed values.

    - What happens if a rising tracer is emitted and the energy of the ambient field is insufficient for its propagation ?

    For propagation, the field, when the rising tracer is initiated, must be greater than or equal to the propagation field. The operating principle of early streamer emission lightning conductors takes into account this condition.

    - Is there a limit to the initiation advance given by early emission streamer devices ?

    Standards limit the initiation advance to 60 µs.

    - How can non-captured impacts on protected sites be explained ?

    By principle, lightning protection cannot be 100% effective whatever type of protection system is used: mesh cage, single point, early streamer emission, etc. However, experience shows that the probability of a non-captured impact when using an early emission streamer device, correctly sized and installed in compliance with standards, is very low and its consequences are always minor as they are due to lower intensity lightning strikes (see electrogeometrical model).

    - Is it possible to model lightning strike capture ?

    Yes, there are several mathematical models allowing lightning strike capture to be simulated. The best known is the electrogeometrical model which is the easiest to use. The others are :
  • Rizk model
  • Lalande model
  • Dellera-Garbagnati model
  • Other models are currently under study.
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