Ground-Fault Protection Analysis for Electrical Installations in a Multi-Story Office Building

Abstract

Reliable ground-fault protection is essential in multi-story building electrical installations because insulation failure, leakage current, and inadequate grounding may increase the risk of electric shock, fire, and equipment damage. This study evaluates the ground-fault protection system of the One-Stop Service Office Building in Bandar Lampung, Indonesia. Field measurements were conducted at 15 grounding points using the three-point fall-of-potential method with a Kyoritsu 4105A earth resistance tester. The installed residual current devices, locally configured as Earth Leakage Circuit Breakers (ELCBs), were assessed against PUIL 2020, IEC 60364, IEC 60479-1, and IEC 61008-1 requirements. Protection coordination and single line-to-ground fault behavior were further analyzed using ETAP 19.0. The measured grounding resistance ranged from 0.93 Ω to 6.21 Ω, with an average value of 2.56 Ω. Twelve grounding points, or 80% of the measured locations, complied with the 5 Ω maximum limit, whereas G-12, G-14, and G-15 exceeded the standard with values of 5.28 Ω, 5.85 Ω, and 6.21 Ω, respectively. The installed 30 mA ELCBs were suitable for personnel protection; however, type AC devices were still used on circuits supplying non-linear loads such as UPS and variable-frequency drives. Several toilet socket circuits were also found without residual current protection. The ELCB–MCB coordination was selective for low-level leakage currents, although simultaneous operation may occur around 160 A. Corrective actions include installing parallel rod electrodes, applying bentonite-based soil treatment, replacing type AC RCDs with type A devices on non-linear circuits, and implementing six-month preventive testing.