Simplified lightning exposure equations
Building dimensions define an equivalent collection area, which is combined with an approximate ground flash density.
Ae = L × W + 6H(L + W) + 9πH²Ng ≈ 0.04 × Td^1.25Nd = Ng × Ae × 10⁻⁶ × Cdwhere:
- Ae
- Equivalent collection area[m²]
- Td
- Thunderstorm days per year
- Ng
- Estimated ground flash density[km⁻² year⁻¹]
- Cd
- Relative location factor
This is an exposure screen, not the complete IEC 62305-2 component-risk calculation.
How to use the Lightning Risk Assessment Calculator
Estimate a simplified lightning exposure score from building collection area, location, thunderstorm activity, and incoming lines. Start by choosing the operating mode, then enter values from nameplates, measurements, or project documents in the units shown. The result updates immediately and keeps intermediate quantities visible for review.
- Confirm the system and calculation mode.
- Enter measured or manufacturer-rated values.
- Review the primary result and intermediate metrics.
- Continue with the related protection or equipment-selection checks.
Calculation method and validation
The equations and symbol definitions above show the complete calculation basis. Inputs are checked before calculation so zero, negative, incompatible, or physically impossible combinations are flagged instead of silently producing a misleading result.
How to interpret the result
Use the main result as a starting value and read every supporting metric. Simplified screening, not the complete IEC 62305-2 component-risk method Thunderstorm days are converted to a broad flash-density estimate A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- Simplified screening, not the complete IEC 62305-2 component-risk method
- Thunderstorm days are converted to a broad flash-density estimate
Selection limits and next checks
Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions. Do not describe this score as a formal IEC 62305 risk assessment. Compare the output with the current applicable standard, local rules, exact VIOX product datasheet, environmental conditions, protection coordination, and the engineer's project requirements before procurement or installation.
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Assumptions
- Simplified screening, not the complete IEC 62305-2 component-risk method
- Thunderstorm days are converted to a broad flash-density estimate
Important Warnings
- Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions.
- Do not describe this score as a formal IEC 62305 risk assessment.