Lightning Protection Calculation [exclusive] Jun 2026

Lightning protection calculations involve determining if a structure requires protection and then designing a system—comprising air terminals, down conductors, and earthing—to meet specific safety standards like or NFPA 780 . The process typically starts with a Risk Assessment to compare the actual risk of a lightning strike ( ) against the tolerable risk ( RTcap R sub cap T ) defined by the application, such as loss of human life ( ) or public service ( 1. Risk Assessment Calculation The first step is determining the Collection Area ( Accap A sub c

Where:

is multiplied by weighting factors (use of structure, construction type, degree of isolation, etc.). If , a protection system is mandatory. 2. Air Termination Design Methods lightning protection calculation

The calculates zones protected by air terminals: A sphere of radius ( r ) (from table above) is rolled over the structure. Any surface touched by the sphere needs direct protection. If , a protection system is mandatory