Nano and micro based epoxy samples have been evaluated for predicting their electrical performance in outdoor high voltage insulation applications. Scanning electron microscopy (SEM) is used to evaluate the shape and the dispersion of the filler material. Space charge characterization and the role of the interface in these materials is evaluated using dielectric spectroscopy on these samples. The results of dielectric spectroscopy reveal the potential of improved electrical performance in terms of dielectric strength and tracking and erosion performance of the nano-filled samples as compared to the micro-filled counterparts. The uniform filler dispersion and the low loss tangent values have been used to theorize the improvement that can be expected from nano-composites in the field of outdoor insulation.