What is a Pressure Switch with “Low Pressure Cut-Off” feature?

Low pressure cut-off switches include all the features of the standard type pressure switch. In addition, the low pressure on-off feature aids in preserving the life of the pump

When pressure in the system drops to approximately 10 PSI below the set cut-in point for any reason such as a low water condition, the switch will open to turn off the pump.

When the condition has been relieved, the manual lever is turned to the start position and, if pressure is restored while holding there, the switch resumes normal operation.

20-40   Low Pressure Cut-Off activated at approx. 10 PSI

30-50   Low Pressure Cut-Off activated at approx. 20 PSI

40-60   Low Pressure Cut-Off activated at approx. 30 PSI


For initial start up of pressure systems utilizing pressure switches with low pressure cut-out feature (Square D Form M4 / BOSHART "BII" PS02LP), one must manually engage the switch (hold the contacts closed) by hold the lever in the “START” position until pump builds the pressure in the tank to within 10 psi of the cut-in pressure setting of the switch.

The manual lever also has an “OFF” position for complete pump shut downs.