Abstract Palm oil (PO) is a potential alternative to mineral oil for electrical insulation and has previously been studied with rice husk (RH) powder as a filler. Research has shown that RH powder enhances the dielectric and physical properties of PO. Additionally, the effect of different preparation methods has been explored, showing further improvements in these properties. In this study, we modified the preparation method by scaling up the sample volume, leading to a positive impact on the properties of PO. To determine the optimal RH concentration for achieving the highest breakdown voltage (BDV), various concentrations of RH in PO were tested according to the IEC 60156 standard. The results demonstrate that the BDV improved significantly compared to previous studies. Moreover, the data revealed a maximum curve trendline in the graph of BDV versus RH concentration. Overall, the modified preparation method yielded better BDV results, with a specific RH concentration resulting with the highest value.