Abstract: A varistor has a disc of ceramic material having opposed faces with face edges. There is an electrode on each face with a gap between each electrode and the edge of the face. Glass passivation is on at least one face in the gap, the passivation not extending from one electrode to the other electrode around the surface of the disc. Because the passivation is only on the planar opposed disc faces, it may be applied in a simple operation such as screen printing. Indeed, the screen printing may be performed while the discs are in the same nest plates as are used for printing of electrode paste. Even though the passivation does not extend from one electrode to the other, it nevertheless breaks a potentially conductive path between the electrodes caused by interaction between the ceramic and encapsulant materials.