Lightning investigation on transmission lines — III

RESULTS of a lightning investigation conducted in cooperation with a number of power companies are presented in this paper which is the fourth of a series of A.I.E.E. papers by the same authors. The principal work in the past 2 years, summarized in this paper, has been a study of the magnitude and polarity of tower current caused by lightning strokes. The data indicate that when the product of the tower current times the tower footing resistance is high, flashover of the line insulator may be expected, and conversely when the product is low flashover usually does not occur.