Impulse and 60-cycle characteristics of driven grounds — III effect of lead in ground installation

GROUND installations comprise physically the ground proper and, in addition, a lead which connects the grounded part (protective device, insulator, overhead ground wire, lightning rod, and so forth) to the ground. The lead (grounding wire or metal structure) is essentially an inductance, while the ground acts as a resistance in the manner discussed previously.¹ These two elements determine in a large measure the total voltage across the ground installation and therefore its performance under lightning discharges.