3.3.7 Tolerable risk of damage and selection of lightning protection measures

When deciding on the selection of lightning protection measures, it must be checked whether or not the determined risk of damage R exceeds an acceptable (i.e. still tolerable) value R_T (Equation 3.3.7.1). For a structure which is sufficiently protected against the effects of a lightning strike we have:

[equation](3.3.7.1)

A representative value for tolerable risk is R_T = 10⁻⁵/a. After thorough investigation, different values can be assigned, taking into account the vulnerability of people inside and outside the structure under investigation and the criticality of the structure and its surroundings for the public due to physical damage. 
The lightning protection measures are intended to limit the risk of damage R to values below the tolerable risk of damage R_T. By calculating the risks of damage in detail and dividing them into the individual risk components R_A, R_B, R_C, R_M, R_U, R_V, R_W and R_Z, the selection of lightning protection measures for a specific structure can be carried out in a highly targeted manner. The basic procedure for selecting the necessary protective measures is shown in the flow chart (Figure 3.3.7.1).