The assessment method described in NF EN 62305-2, IEC 62305-2 and NF C 17-102 standards is the most complete reference involving high number of parameters.
The basic method of this assessment lays in comparing the risk of a structure to a “tolerable”risk. If the level of risk on the structure is lower than the tolerable one, the structure is considered as “self-protected”, then if the risk is higher, the structure needs protection.
4 types of risks may be defined within lightning risk assessment according to NF EN 62305-2 standard :
R1 : Risk of human life casualty
R2 : Risk of public service loss
R3 : Risk of cultural legacy loss
R4 : Risk of economic values loss
Each type of risk is compared to a tolerable risk.
Risk 1 (main identified risk) is the sum of the included risks.
There are 4 levels of protection. Level 1 is the most severe.
UTE C 17-108 guide provides a simplified method of risk assessment. The method is called simplified because it includes only a limited number of parameters compared to the so-called complete method in EN 62305-2 standard. The other parameters were arbitrarily predetermined.
It is for this reason that this method only applies to structures :
The methodology for choosing the level of protection is then exactly the same as for the full method, i.e the level of protection is gradually increased until a lower tolerable risk is reached.