Influence of Electrode Spacing on Grounding Resistances in Electrical Networks for Effective Lightning Protection

Anedi Oko Ganongo; Rodolphe Gomba; Nianga-Apila; Linné Lovel Atsembou Obita; Branham Jacques Lévi Makanga; Mathurin Gogom; Gilbert Ganga

doi:10.46604/aiti.2026.15895

Authors

Anedi Oko Ganongo Polytechnic Superior National School, Marien Ngouabi University, Brazzaville, Congo
Rodolphe Gomba Polytechnic Superior National School, Marien Ngouabi University, Brazzaville, Congo
Nianga-Apila Polytechnic Superior National School, Marien Ngouabi University, Brazzaville, Congo
Linné Lovel Atsembou Obita Polytechnic Superior National School, Marien Ngouabi University, Brazzaville, Congo
Branham Jacques Lévi Makanga Polytechnic Superior National School, Marien Ngouabi University, Brazzaville, Congo
Mathurin Gogom Polytechnic Superior National School, Marien Ngouabi University, Brazzaville, Congo
Gilbert Ganga Polytechnic Superior National School, Marien Ngouabi University, Brazzaville, Congo

DOI:

https://doi.org/10.46604/aiti.2026.15895

Keywords:

electrode spacing, grounding resistance, lightning protection, soil resistivity, transmission line safety

Abstract

This study aims to analyze the influence of inter-electrode spacing on grounding resistance in high-voltage transmission networks. A simplified analytical model is applied to a case study on the Djiri-Ngo 220 kV line (Republic of the Congo), considering two representative soil types: clayey and siliceous sand. The grounding resistance is calculated by varying the number of electrodes and their spacing. The results show that increasing electrode spacing reduces grounding resistance. In certain configurations, the improvement exceeding 50 % when the spacing is increased from 5 m to 25 m. A saturation threshold is identified, beyond which further increases in spacing yields diminishing returns. Electrode spacing proves to be a key design factor, sometimes more influential than the number of electrodes. The proposed parametric geometric analysis offers a practical and cost-effective strategy for grounding system design, emphasizing the importance of adapting configurations to local geotechnical conditions.

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