The Sensor is an electronic switch with stainless steel probes encapsulated in impact resistant moulded rubber. When the probes touch water, the pump will start and continue to operate for one minute after the water falls below it. However, if the water touches the probe within this time, the “stop” signal is cancelled and the pump continues to run until the water is cleared. It has an integral gland, for fitting to single phase Tsurumi pumps. NB This product is electronic, so damage may occur from the high current and high voltage applied during a portable appliance test. We recommend bypassing the switch, for a visual inspection only, during a test.