Primary electron energy (Ep) dependent change in target current was studied on a grounded Au film in the range of 40 to 3500 eV. The current jumped suddenly from a negative to a positive value at ∼650 eV with increasing Ep, while it disappeared in reverse sweep and with increasing substrate temperature. Detailed analysis suggests that Ep dependent surface charging plays a pivotal role in flashover. Prior to critical Ep in the forward sweep, a gradual shift of a double peak-like structure towards high kinetic energy region in the secondary electron spectra also confirms surface charging effect. © 2013 AIP Publishing LLC.