IEC 62305-2 Risk Assessment Workbook (Excel)

IEC 62305-2 defines a structured, probabilistic framework for assessing the risk (R) associated with lightning strikes to structures or services, expressed as the product of the annual number of dangerous events (N) and the consequential loss (L). The Excel workbook operationalizes this standard by decomposing total risk into four risk components (R1–R4), each corresponding to distinct types of loss: loss of human life (R1), loss of service to the public (R2), loss of cultural heritage (R3), and loss of economic value (R4). Users input data such as location (lightning ground flash density Ng), structural dimensions, construction materials, internal system sensitivity, occupancy type, and existing protection measures (e.g., LPS, SPDs, bonding); the workbook then computes individual risk components and compares them against tolerable risk thresholds (RT) defined in Annex A of IEC 62305-2. Key automation features include dynamic calculation of collection areas, probability factors (e.g., Pd for damage probability, C for consequence), and iterative evaluation of risk reduction achieved by mitigation measures—enabling engineers to validate compliance, optimize protection strategies, and generate auditable assessment reports. The workbook typically includes validation checks, built-in lookup tables (e.g., for material resistivity, surge protection device (SPD) coordination), and sensitivity analysis tools to identify dominant risk contributors.