A filtered feedthrough that does not block passage of gas in a helium leak test and enables testing of the hermeticity of the feedthrough while inhibiting high voltage arcing is disclosed in single filtered feedthrough and multiple filtered feedthrough array configurations. Each filtered feedthrough comprises a ferrule, an insulator, a feedthrough pin, a filter element, and a pre-formed insulative barrier or spacer located in an interior space between the feedthrough insulator and the filter element rather than a non-conductive adhesive filling the interior space. A gas flow path or pathway extends from the interior space to the exterior of the feedthrough bypassing each filter element. Any leak test gas applied in a hermeticity test and passing through defects in the feedthrough insulator or its attachment to the feedthrough pin or ferrule enters the interior space. The gas pathway extends from an interior space through one or more side wall hole of the ferrule and/or through one or more gap between the ferrule interior surface and the outer surface of the filter element.