Corona inception voltage (CIV) due to water droplet sitting over the surface of epoxy nanocomposite material depends on supply voltage frequency, the conductivity of water droplet and the contact angle of the test specimens. The contact angle of the specimen and CIV due to water droplet has a direct correlation. It is realised that the CIV is high under negative DC and the least under AC voltages. Surface charge accumulation studies indicate that the accumulated charge and its decay time constant reduces in the damage-caused zone due to corona activity. The ultra-high frequency (UHF) signal generated due to water droplet-initiated corona activity has frequency content in the range of 0.8-1 GHz. The localisation of incipient discharges is demonstrated by using the non-iterative technique and the cross recurrence plot (CRP) technique is used to estimate the time difference of arrival (TDOA) of UHF signals generated due to water droplet-initiated discharge. Laser-induced breakdown spectroscopy (LIBS) depicts the elemental composition and reveals the difference in plasma temperature and threshold fluence between all the test specimens. In short, the performance of ion trapping particle filled epoxy nanocomposite performance is found to be best followed by titania filled epoxy nanocomposite and the base epoxy resin. © The Institution of Engineering and Technology 2018.