LIGHTNING PROTECTION ZONES
Use the rolling sphere method (Figure 6) to determine where it is safe to mount equipment. An
imaginary sphere, typically 50 meters in radius, is rolled over the structure. Where the sphere rests
against the ground and a strike termination device (such as a finial or ground bar), all the space
under the sphere is considered to be in the zone of protection (Zone B). Similarly, where the
sphere rests on two finials, the space under the sphere is considered to be in the zone of
protection.