Crowbarring is achieved when a magnetically driven arc contacts an electrode in the crowbar circuit. No auxiliary timing circuitry is required and, at the time of crowbarring, the arc divides into two parts such that the load is isolated from the source. A discharge which peaks at 200 kA in 4 &mgr;s is crowbarred and displays a 50‐&mgr;s e‐folding time with a ripple current of less than 5%. Main switching and crowbarring are combined in a single 3‐electrode spark gap which is triggered by a pin between two of the electrodes. Crowbar timing is insensitive to gap dimensions and to current magnitude. Pin placement is critical but little energy is dissipated in the neighborhood of the trigger pin.