Lightning Protection Lightning is an electrical discharge pulse in the atmosphere, which averages 20 kA or more in current. Commonly, these discharges are viewed as a flash from cloud to ground, although it can flash from the ground to the cloud. It can easily explode a tree with a direct strike.
Lightning strikes are somewhat predictable over a geographical region.
The isokeraunic level is the number of thunderstorm days per year. This isokeraunic number varies from over 100 along the Gulf coast of Florida to less than 5 in the Pacific Northwest. Nevertheless, virtually all areas in North America are subject to lightning strikes to some degree. Exterior equipment, rooftop equipment, and equipment connected to aerial and buried copper cables are subject to possible damage. In contrast, in areas of heavy lightning activity, it is quite common to use protected-type line repeaters regardless of whether the cable is aerial or buried.