The purpose of this research is to determine if an X-ray-induced partial discharge (pd) measuring system can improve the pd detection sensitivity and provide the ability to locate voids in epoxy spacers for gas-insulated switchgear. Several published reports describe the use of x-rays to stimulate partial discharge activity in solid insulation systems [1,2]. In these studies, x-rays reduced the discharge inception voltage (DIV) and/or increased the pd repetition rate. With suitable control of the x-ray source, these properties can be used to locate the site of pd in an insulation system [1], or can be used to increase the signal-to-noise ratio of pd detection [2]. However little routine use is made of this x-ray effect in industry, perhaps because the advantages have not been proved sufficient to warrant the added complexity.