This float switch of the brand MAC3 is ideally suited to control the level of a tank, a reservoir or a pond. Mac3 series can be install in industrial buildings and is suitable for use in sewage water. The switch comes with a 3 meter cable and a balance weight. The waterproof switch floats on the surface. The balance weight can be attached to the cable and placed into the water to set the desired control level. The free length of the cable (between the balance weight and the switch) determines the lowest and the highest fluid level. The smallest controllable level change is approximately 20 cm. The device switches at an angle of about +20 or -45 degrees, through a mechanical switch. The rated switching max voltage is 250V AC, but can be used at lower voltage (i.e. 110V, 220V, 240V, etc.). The switch has a changeover contact, so it can be used for normally closed (NC) or normally open (NO) operation. It has three lead wires: common, NC and NO. By connecting the circuit to the common lead and either one of the other two lead wires, you can choose between NC and NO operation. In other words, you can decide whether the switch should make contact when the float is in the lifted or hanging situation. Typically, a normally open float switch is "on" when the float is down below a pre-set level (gravity forces it down) and turns "off" as it rises to the pre-set level. A normally closed float switch works opposite. It is closed when hanging down and on when it is above the pre-set level. NC or NO operation depends on wiring. It can be used to switch a pump or an alarm and has an IP68 rating.