Spark-gap device, particularly high-voltage spark-gap device

Spark-gap device including two discharge electrodes (2; 3) each having an elongated conductor portion (10; 5), called the active portion, with a connecting longitudinal end (11; 7) fixed to a connector. The electrodes are arranged in such a way that, when an electric arc is generated, the arc is formed between the active portions and the resulting electric current induces a magnetic field moving the electric arc along the active portions, preferably at an erosion-limiting high speed. At least a discharge electrode further includes at least a second conductor portion (9, 16; 6), called the passive portion, electrically connected to the connector and/or the active portion and with a form adapted to prevent a spontaneous electric arc from being inopportunely generated in normal usage conditions of the device.