Rolling Sphere Method Calculator -

: Never trust manual approximations for critical infrastructure. Run the rolling sphere simulation, verify the red zones, and then build with confidence. About the author: This article is based on principles from IEC 62305 and IEEE 998. Always consult local codes and a licensed engineer for final designs.

: The tool instantly shows that at 19 m separation, the top 0.8 m of the arrester remains exposed. You then add a second mast, and the overlapping spheres create full protection up to 28 m separation. rolling sphere method calculator

Introduction

: Using the formula, the maximum distance is ≈ 18.7 m. Always consult local codes and a licensed engineer

For decades, the protection of structures against direct lightning strikes has relied on a few key geometric models. Among them, the stands out as the most intuitive and physically accurate representation of how lightning intercepts a structure. Unlike the older "cone of protection" method, RSM accounts for the actual striking distance of lightning, making it indispensable for protecting complex or sensitive facilities like substations, data centers, petrochemical plants, and tall buildings. Introduction : Using the formula, the maximum distance

: How far can the arrester be from the mast?

The sphere’s radius is not arbitrary. It is derived from the formula, which relates to the peak lightning current. The most common standard (IEC 62305 and NFPA 780) defines protection levels (I to IV) with corresponding sphere radii: