Abstract: A lightning arrester including a metallic enclosure with an opening, a first electrode of electrically conducting metal traversing the enclosure opening and having a first discharge surface within the enclosure, a plug of electrically insulating material placed about the first electrode to hermetically seal the enclosure opening, and an inert gas mixture filling the enclosure. The first electrode has a thin long cylindrical portion and a flat end portion, like a nailhead, which provides the first discharge surface. Portions of the enclosure provide a second electrode having a second discharge surface within the enclosure which faces the first discharge surface, with a predetermined gap therebetween. The long thin portion of the first electrode within the enclosure is surrounded by a sleeve composed of a fusible, electrically and thermally conducting material.