The upper end of the rod is furnished with sharp points and the lower end is fixed to a metal plate well buried in wet earth.
During a thunderstorm, when a charged cloud passes above the points of the lightning conductor, an induced charge of the opposite kind accumulates at the points. This results in the charging of the air particles by contact around the points.
This creates an electric wind directed toward the cloud. The cloud thereby becomes gradually discharged. If on other hand, the difference of potential between the cloud and the conductor is so great as to produce a discharge, the lightning conductor passes on the discharge to earth without damaging the building.