Investigations into Mechanisms of Involvement of Objects and Personnel in Lightning Disasters

Cloud to ground lightning causes damage to objects and injures people by different mechanisms like direct hit, contact voltage, side flash, step voltage etc. Understanding the different ways of involvement of objects and personnel in lightning disasters is helpful in deciding the type and level of external protection. Details of investigations conducted in 47 lightning disasters spread over several years are presented. The different types of mechanisms of involvement of objects and personnel in these incidents are discussed. All the incidents investigated were from Kerala, India which is a region of relatively high vegetation density. In 51% of the cases objects and personnel were found to have got involved by ground conduction of lightning energy into dwellings. Some of the cases of ground conduction involvements are unusual. The high degree of damage in some of the unusual cases is attributed to the continuing current component. The role of metal objects in charge collection and dissipation is also discussed. The relative importance of ring conductor to the lightning conductor in places of high vegetation density is brought out.