Identification of Subsurface for Grounding Installation System Using Geoelectrical Method: Case Study of Waru Substation, Sidoarjo, East JavaAnisatu Ainun Khoirunida, Juan Pandu Gya Nur Rochman and Ayi Syaeful BahriBIO Web Conf., 157 (2025) 05013DOI: https://doi.org/10.1051/bioconf/202515705013