Collection:Cable Float Switches

Cable float switches hang on their own cable in a tank, well or sump pit and switch when the rising liquid tilts the float. They are a simple way to start or stop a pump, or to give a high-level or low-level alarm, in water and wastewater applications.

Inside the float, a mechanical switch changes over when the float tilts past a set angle. A weight on the cable holds the float at the required depth, and the free cable length between the weight and the float sets the difference between the switch-on and switch-off level. Because the switch has a changeover contact, the same model can fill or empty a tank: wire it as normally open or normally closed, depending on whether the pump must run when the level is low or when it is high.

Choosing a cable float switch

• Medium: check that the switch is made for the liquid. Some versions are for clean water, others for sewage and industrial wastewater.
• Cable length: choose a cable that reaches the control box without a joint in the tank.
• Electrical load: check that the contact rating suits the pump motor, or switch the pump through a contactor.
• Hazardous areas: where explosive gas can occur, for example in sewage pits, use an ATEX-approved version and connect it as its manual specifies.

A cable float switch needs free space to swing, so it does not suit small or closed tanks or applications that need an exact switch point. For hydraulic and oil tanks, use a vertical float switch instead.