I. Introduction
This Power system is generally protected from lightning strokes by surge arresters which are provided with a low earth resistance connection to enable the large currents encountered to be effectively discharged to the general mass of earth which offers some resistance to the flow of current. This earth resistance depends on electrode arrangements as well as the surrounding soil resistivity. Ideally, to maintain a reference potential for instrument safety, to protect against static electricity, and to limit the equipment ground voltage for operator safety, the ground resistance should be zero ohms. In reality, this value cannot be achieved. Therefore, low ground resistance values are required and typical values are usually specified by utilities for different situations.