Spark gap apparatus

A spark gap for protecting electronic circuits from excessive electrical surges comprises a substrate containing an opening, a dielectric medium occupying the opening, and first and second electrodes. The first electrode is embedded in the substrate, on one side of the opening, and has a first conductive surface that extends through the substrate and is substantially exposed in the opening and to the dielectric medium. The second electrode is embedded in the substrate, on another side of the opening, and has a second conductive surface that extends through the substrate and is substantially exposed in the opening and to the dielectric medium. The first conductive surface is in opposing relation to the second conductive surface, and they are spaced apart by a predetermined distance to establish a gap width. An electrical arc is generated across the opening when a voltage potential difference between the conductive surfaces exceeds a threshold value.