is multiplied by weighting factors (use of structure, construction type, degree of isolation, etc.). If , a protection system is mandatory. 2. Air Termination Design Methods
), which is the effective ground area a structure "covers" for lightning strikes. lightning protection calculation
Once the need is established, engineers use specific mathematical models to place air terminals (rods) and conductors. The Rolling Sphere Method is multiplied by weighting factors (use of structure,
$$N = \frac\textPerimeter of Building\textSpacing Distance$$ degree of isolation
Since single rods rarely achieve < 10 Ohms in high-resistivity soil, parallel rods are used. $$R_total = \fracR_En \times F$$