An automated ‘arc and spark’ test method has been developed for economical high-voltage testing of vacuum interrupters, taking into consideration both the physics of vacuum breakdown and realistic service conditions. Each breakdown test is preceded by a well defined but variable switching operation. Test control and evaluation by a computer provide fast and economic execution, even of large series of complex tests. Short descriptions of devices for breakdown detection and prebreakdown field emission current measurement are added. The presented test method concerns the dielectric performance of an open interrupter, but not its dielectric recovery at current interruption.