Footing Resistance Design for Reliable OHL Lightning and Fault Protection

Medium-voltage (MV) overhead lines supplying critical industrial loads are increasingly exposed to lightning-induced overvoltages, switching transients, and adverse environmental conditions. Although overhead ground wires, surge arresters, and conventional protection schemes are widely applied, repeated failures continue to occur in practice, often despite correct insulation coordination and relay operation. Post-event investigations frequently identify inadequate grounding performance, particularly excessive structure footing resistance, as a dominant contributor. Existing standards recognize the importance of grounding for lightning performance but treat footing resistance primarily as a prescriptive constraint rather than a performance-based design variable . This paper presents a…