HISTORIC ANGLE OF PROTECTION . . .

FLASH BACK ==================> Benjamin Franklin — (1750s)

The roots of modern lightning protection go back to Benjamin Franklin's lightning rod experiments in the 1750s. His pointed metal rod provided a preferential path for lightning current to reach earth.

At this stage, there was no standardized protection angle or protection radius. The concept was primarily based on placing a conductor above the structure and providing a conductive path to earth.

Early "Cone of Protection" concept

As lightning protection engineering developed, engineers began representing the protected region around a vertical air terminal as a geometrical cone.

IN THE EARLIER 80'S THE BASIC CONCEPT WAS . . .

A vertical lightning rod protects an area below it within a specified angle measured from the rod to the protected surface.