The protected Area of a lightning rod is not static, pre-determined based on dynamic factors. Such as the shape of the structure to be protected, the masses of metal and metal objects on the outside of the building, the thermal variations, the intensity of electric field in the region to be protected, etc. The main methods of protection are: method Franklin on the basis of a proposal by Benjamin Franklin, has been subject to enhancements over time. According to current regulations, Franklin type lightning arrester are installed to protect the volume of a cone, where the sensor is the angle’s vertex between the generator and the center of the cone, which vary according to the level of protection and the height of the building (NBR5419/2001). Faraday cage method method is to install a system of sensors formed by horizontal wires connected in the form of Grill, a method widely used in Europe.

Is based on the theory of Faraday, whereby the field inside a cage is not valid even when their drivers go through a stream of high value, as it is necessary that the current is distributed evenly over the surface. How much shorter the distance between the conductors of the mesh, the better will be the obtained protection (NBR 5419/2001). Method Eletrogeometrico model Eletrogeometrico also known as rolling sphere, the fictional sphere or ball method is an evolution of the type of protection Franklin method, where the tangent instead of straight is parabolic. This method was introduced in the 1970s and was developed by the engineering of transmission lines in Europe with the objective of minimizing the damage with cuts of these lines. In conclusion, this model consists of rolling a ball in the building of fiction in all directions, so the determination of places most likely to be struck by lightning and as a precept that these places are local leaders with the potential to generate up to should rush to comply with the main drawback.