282 / 2022-03-15 02:29:04

Quantitative study on efficacy of lightning rod on building

Lightning,Lightning Protection,Lightning rod,upward leader

The efficacy of a lightning rod on the building top is determined by its ability to launch a stable upward leader under the influence of descending lightning leader. Several factors like position, tip radius, the height of the rod, dimension of the building, etc. affect the efficacy of lightning rod. The purpose of this paper is to quantify the influence of some of these parameters such as rod position and height, building width on the upward leader inception in terms of the stabilization field.

Field computation is performed using Charge Simulation Method (CSM) where the buildings and rods are modelled with point charges. The downward lightning leader is modelled with a vertical channel with specific charge distribution as suggested by Cooray and Rakov (2007). Becerra and Cooray’s model [1] for inception and propagation of positive connecting leader is employed to determine stable leader inception. As suggested in [1], the stabilization field is determined from ambient field at the rod tip when the upward leader attains a length of 2m. An average gradient between leader tip and leader inception point of more than 500 kV/m is considered as a criterion of streamer mode of bridging.

In the paper, it is shown that smaller rods at the middle of the building fail to incept upward leader for higher width of the building. On the other hand, a rod placed at the corner is significantly efficient to initiate a connecting positive leader. Longer the height of the rod, better the efficacy.