A "Normally Open" float switch turns the pump off when the water level is too low. In other words, as the water level drops, this float switch flips down and opens the circuit (which cuts off power). This is the most effective pump control system to ensure that your cistern pump does not burn up if your cistern or rain tank runs dry. If pumps start to draw air (i.e., when there's no water in the system), the pump loses its suction, and instead of water running through the pump and cooling the pump motor, air moves through the pump and the motor gets hotter and hotter the longer air is being circulated instead of water. This results in the motor burning up.
Installing a "Normally Open" float switch with your pump will ensure the pump turns off before water in the tank is depleted, thus preventing the pump from ever running dry and burning up.
Our Normally Open 120/230V Float Switch is a 15amp rated pump switch with heavy duty contacts for maximum pump starting loads.