In this article a critical component for pulsed power applications is described: the heavy-duty switch. The design of a coaxial, high repetition rate, large average power, and long lifetime spark-gap switch is discussed. The switch is used with a fail-free LCR trigger circuit. Critical issues for switch design are presented together with experimental results. It is observed that the switch has a good stability, and its lifetime is estimated to be in the order of 1010 shots (∼106C) at 10J∕pulse, 60kV and 100ns pulses. Measurements were performed with 20 and 34kV average switching voltage (100ns pulses, energy per pulse 0.4 and 0.75J, respectively). For up to 450pulses∕s (pps), pre-firing can be prevented by increasing the gap pressure (up to 2.5 and 7bars, respectively), no gas flush is required. Above 450pps, up to 820pps, a forced gas flow of maximal 35Nm3∕h, is required for stable operation. Measurements on the time delay and jitter of the switch demonstrate that these values are influenced by pressure, flow, and pulse repetition rate. For 34kV average switching voltage the time delay and time jitter vary between 35 and 250 and 10 and 80μs, respectively. For 20kV average switching voltage these values are: 30–160 and 4–50μs. During a test run of 2.5h (at 100Hz, 0.75J∕pulse) the feasibility of the switch was proved, and the switching voltage jitter was less than 0.7%.