This pressure switch signals the pump to start when the water system drops to 40 psi (factory set) and stops at 60 psi (factory set). This switch is to be used with submersible well or jet pumps. It can be wired 115-Volt or 230-Volt. This switch must be used in conjunction with a well pressure tank. The air pressure in the well tank, when empty of all water, must be set to 38 psi or the switch will not operate properly.