A technique is discussed which can be used to simulate the very high average power environment encountered when high power switches are operated in a repetitively pulsed mode. An operational test facility is described which has been used to test spark gap switches at voltages up to 80 kV, pulse repetition rates up to 500 pps, and simulated average power levels of several megawatts. The power consumed in the test facility depends on the power simulated and the voltages used in the test circuit. Typically, the electrical duty experienced by a switch transferring several megawatts average power can be provided with a few hundred kilowatts average power using the simulation concept described here.