Within the limitations inherent in mechanical switching devices, mercury wetted contact relays can provide a simple and effective solution to a number of experimental problems. Details of the following applications are given and their limitations are discussed: the generation of nanosecond electron pulses with energies up to 50 kev; the production of fast rising millisecond voltage pulses of up to ±1800 v; a compact, low capacity gating unit which allows the application of high voltage pulses to crystal specimens, or other apparatus, coupled capacitatively to the input of sensitive amplifying equipment; a technique employing two relays which has been used to study the decay of excess carriers injected in an insulating solid by a fast rising voltage step.