IEC 62305-1 is part of a four-part suite that must be used together for a complete safety solution: IEC BS EN 62305 1 - 4.pdf - ABB
The standard establishes four Lightning Protection Levels (LPL I to IV) based on the severity of the strike a system can handle.
The primary goal of IEC 62305 is the preservation of life. The standard dictates the "Lightning Protection Level" (LPL) required for a building. For example, a hospital or a school requires a higher level of protection (lower risk threshold) than an agricultural shed. The standard provides the formulas to calculate the "tolerable risk" ($R_T$) versus the "calculated risk" ($R$), ensuring that the design ensures safety for occupants.
Assuming you have obtained a legitimate copy of , here is the correct workflow: