Laboratory investigation of lightning striking distance to rod and transmission line

The striking distance was investigated by means of laboratory experiments to study the impact of factors such as rod height, ground wire height, and polarity of impulses. The researches which were performed at the Mississippi State University High Voltage Laboratory during the 1998-2009 are summarized and presented. Negative and positive impulses were applied to a conducting rod to represent both polarities of lightning downward leaders. Different configurations of lightning protection system, a vertical rod and a horizontal conductor, were studied. Experimental results were compared to published results by different authors. Mathematical equations were developed to estimate the striking distance under both negative and positive polarities of lightning strokes. Results of studies will help to design the proper placement of a lightning rod or an overhead ground wire and minimize the risk of direct lightning strikes to protected objects.