Square D FSG2J24CP — Pumptrol Pressure Switch for Well Pumps (40-60 PSI)

What is it and what's it for?

It's the pump's 'thermostat,' but for pressure instead of temperature: it measures the water pressure in the pipe and sends the electrical signal that starts the pump the moment pressure drops below a set point (like when you open a faucet) and shuts it off once pressure climbs back up. Without this part, a well pump has no way of knowing when to turn itself on or off.

Real-world use cases

• At home: You installed the WAYNE SWS50 or the Red Lion from this ranking and realized neither one ships with this switch — without it, you'd have to turn the pump on and off by hand every time you need water; with this switch, the system starts on its own when you open the faucet and cuts off when you close it.
• In a business or workshop: A plumber installing well systems for multiple clients picks this specific model over an unbranded generic one because they know replacement parts and technical support will be available for years — something they can't guarantee with an unrecognized-brand switch.

How to avoid buying the wrong one

• This is NOT a pressure tank, it's only the switch — if your setup doesn't already have a pressure tank, you need to add one separately to keep the pump from short-cycling every few seconds.
• It ships factory-set to the 40-60 PSI range; if your pump needs a different range (like the 30-50 PSI factory preset on the WAYNE SWS50 in this ranking), you'll need to manually readjust it with the range-spring nut — it doesn't arrive pre-tuned for every pump.
• Confirm your setup uses the standard 1/4" NPSF connection before buying — it's the most common in residential systems, but if yours is different you'll need a separate adapter.