Running the full risk-of-loss-of-life calculation for a modest warehouse finds the risk is already below the tolerable threshold — no LPS is strictly required by the standard's own numbers.
| Structure dimensions | 15 m x 20 m x 6 m high |
| Ground flash density | 4 flashes/km²/year |
| Existing LPS | None |
| Persons in the zone of loss | 5 of 5 total occupants |
| Time occupied | 8760 h/year (continuously staffed) |
| Tolerable risk (R1, per IEC 62305) | 1 x 10⁻⁵ per year |
This example covers the free-tier structure-only risk (loss of human life from direct strikes to the structure). Risk contributions from connected power/telecom lines are a separate subscriber-tier calculation and are not included here.
With no LPS installed, the probability factor Pb (damage probability) is at its maximum (1.0), reflecting no protection at all.
| Check | Requirement | Actual | Status |
|---|---|---|---|
| Total risk of loss of human life (R1) | ≤ 1 x 10⁻⁵ per year | 1.03 x 10⁻⁶ per year | ✓ PASS |
Key insight: A 'no LPS required' result from this kind of risk assessment is a legitimate, standard-compliant outcome, not a sign the assessment is incomplete — IEC 62305 is explicitly a risk-based standard, not a blanket 'every building needs lightning rods' rule. That said, this example only evaluates structure-only risk; connected overhead power or telecom lines can add meaningfully to total risk, and a full assessment for a real building should include them.
Every input in this example is editable in the live calculator — free, no signup.
Open Lightning Protection calculator →Yes — the loss factor terms (LA, LB in this calculation) scale with the type of loss being evaluated and the specific structure's fire risk provisions, so a structure storing flammable materials or serving a higher-risk occupancy type would show meaningfully higher risk for the same physical dimensions and lightning flash density, potentially crossing the tolerable threshold and requiring an LPS.
Overhead lines entering a structure give lightning current an additional path in, which is why IEC 62305 adds separate risk terms (Ru, Rv) for connected lines based on their length, routing, shielding and the equipment's withstand voltage — for a structure with long unshielded overhead service lines, these terms can be the dominant contributor to total risk, sometimes tipping an otherwise-tolerable result over the threshold.