This study aims to determine the effect of variations in SiO₂ layer thickness on the Partial Discharge Inception Voltage (PDIV) and Breakdown Voltage (BDV) values in epoxy resin composites. The SiO₂ layer was prepared using a TEOS-based sol-gel method and applied by spray coating technique on the sample surface. The thickness variations tested were 20 µm, 30 µm, 40 µm, 50 µm, and 60 µm…