Abstract: A spark gap for use in the power supply of medium voltage and low voltage networks, wherein two rotationally symmetric electrodes are arranged in a housing and an arc space is provided between the two electrodes for the arc which is formed in the event of a spark-over and its follow-on current. The two electrodes are arranged in the direction of the longitudinal center axis of the spark gap one behind the other and at a distance from each other. A disk of an electrically insulating material is positioned perpendicularly of the longitudinal center axis so as to electrically separate the two electrodes from each other. The insulating disk has an opening adapted to the hollow cylindrical inner space forming the spark-over place for the arc. The arc space includes a rotationally symmetric arc chamber arranged concentrically with the longitudinal center axis for the follow-on current. The arc chamber is positioned between the two electrodes.