NONE 20260529113233649 wseas/wseas content-registration-form+ja@crossref.org content-registration-form WSEAS TRANSACTIONS ON SYSTEMS 1109-2777 2224-2678 Motom Sato Department of Medical Technology & Clinical Engineering, Gunma University of Health and Welfare, 1.191-1 Kawamagari-machi, Maebashi-shi. Gunma 371-0823, JAPAN Chihiro Nishimoto Department of Medical Technology & Clinical Engineering, Gunma University of Health and Welfare, 1.191-1 Kawamagari-machi, Maebashi-shi. Gunma 371-0823, JAPAN Naoki Kusumoto Department of Medical Technology & Clinical Engineering, Gunma University of Health and Welfare, 1.191-1 Kawamagari-machi, Maebashi-shi. Gunma 371-0823, JAPAN Hitoshi Kijima Department of Medical Technology & Clinical Engineering, Gunma University of Health and Welfare, 1.191-1 Kawamagari-machi, Maebashi-shi. Gunma 371-0823, JAPAN This paper investigates the rate of increase in earth resistance due to corrosion of the earth electrode. When the earth electrode corrodes, the predetermined value cannot be maintained due to the earth resistance increasing. As there has been no study of the relationship between corrosion of the earth electrode and earth resistance, it is difficult to predict the rate of increase in earth resistance due to electrode corrosion. In this paper, we have derived a calculation formula for determining changes in electrode shape that takes both electrolytic corrosion and natural corrosion into account, and this makes it possible to estimate the lifetime of the earth electrode. Furthermore, by using this calculation formula, it is possible to predict the rate of increase in earthing resistance value when electrolytic corrosion and natural corrosion progress simultaneously. 05 29 2026 05 29 2026 345 27 https://creativecommons.org/licenses/by/4.0/deed.en_US 10.37394/23202.2026.25.27 https://wseas.com/journals/systems/2026/a545102-1057.pdf John Tarilanyo Afa, Soil corrosion and earthing, ISBN: 978-3-656-41265-6, 2013. (text in Japanese) Electrolytic corrosion, Japan electric engineering association, 2024, [Online]. https://jeea.or.jp/course/contents/09101/ (Accessed Date: February 24, 2026). Isac K Nti, Albert Y. Appiah, Owusu NyarkoBoateng, Assessment and prediction of earthing resistance in domestic installation, Nti - 2020 - Engineering Reports - Wiley Online Library, 2020. doi: 10.1002/eng2.12090. Isumujianto, A Damar Aji, Isdawimah, Nuha Nadhiroh, Real-time Measurement for Controlling Grounding Resistance, ASAIS 2019, pp.120-125. doi: 10.5220/0009910801200125. Roman Sikora, Adrian Wilk, Impact of seasons on industrial grounding resistance, Scientific Report, vol. 15, 11962, 2025 doi: 10.1038/s41598-025-96702-3. Soil resistivity and ground resistance for dry and wet soil, Journal of Modern Power Systems and Clean Energy, Vol. 5, pp.290-297, 2017 (Accessed Date: February 24, 2026). Wenner Soil Resistivity Test Method (4- Electrode) - CCPTools https://ccptools.com/2023/05/wenner-soilresistivity-test-method-4-electrode/ (Accessed Date: February 24, 2026) (text in Japanese) Pipes and tubes, Nippon steel, 2024, [Online]. https://www.nipponsteel.com/product/pipe/ser vice/03.html (Accessed Date: February 24, 2026). Hitoshi Kijima, Method of determining the degree of corrosion of metal earth rods, Japanese patent No. H8-27116, 1996. E D Sunde, Earth conduction effects in transmission systems, D Van Nostrand Com Inc. 1949. Dwight, Calculation of resistance to ground, Transaction. Am. Elec. Eng. Vol.55, 1936. Iron | Fe | CID 23925 - PubChem, [Online]. https://pubchem.ncbi.nlm.nih.gov/compound/I ron (Accessed Date: February 24, 2026).