Lightning Safety with a Grounded Air-Terminal: Is there a Difference between Indoor and Outdoor?

Abstract

This study shows that in most cases of non-sturdy structures, protected with a grounded air terminal, the electric field inside the structure, is not much different from the case where the structure is not present. In order to have a significant difference in the electric field, the structure should be made of a material of which the conductivity is in the order of 0.001 S/m. The structural materials that are used in many applications have a much smaller conductivity. Such structures include housing for underprivileged communities, shelters in outdoor working environments, cabanas, tents, chalets and cottages etc. found in tourism, adventure, and entertainment industries. The potential gradient underneath the ground surface is also not altered noticeably when the area is enclosed by the covering structure. Thus, it is argued in this study that if the occupants inside such structures are protected by an isolated and grounded air terminal designed according to the IEC 62305 standards, the same could be applied to a person at an outdoor location.