I have an irrigation system supplied by a 3/4 HP shallow well pump. I noticed that there is water leaking from the pressure switch that is connected to the well pump casing. The pump itself is not leaking. The switch is a "Square D". Does water actually enter the switch to make it operate. Why would water be anywhere near an electrical switch. Should I just replace the switch? Thanks

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Originally Posted by transistor2002

The switch is a "Square D". Does water actually enter the switch to make it operate. Why would water be anywhere near an electrical switch. Should I just replace the switch?? Thanks

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Hi! transistor2002, and welcome to AMHD :)

The switch is built in two parts:

*One is hydraulic/pneumatic, A tapped line from the pump casing to a diaphragm mounted on the switch.
As the pump runs, pressure builds until it reaches the setting on the switch. The only way the switch knows the pressure is by getting a reading from the pump.
The sending unit is pneumatic until the diaphragm starts leaking, then it tries to work with both.
There may be WIFI, but I haven't seen it yet for home use.

*Two is electrical, that works off that diaphragm.
As the pressure increases the diaphragm swells, pushing on a lever plate, that overcomes the resistance applied by the setting springs. When this setting is reached, the contacts are pushed apart, and the pump shuts off.

Your diaphragm has symptoms of either wear or a hole.
There are two styles:

* One is a sealed diaphragm, in this case you have to get a new one.
* Two has screws around the perimeter.
With the Power locked out take cover to switch off, and see if you can tighten up the screws evenly.
Return unit to service to see if leak has been corrected.

I have rebuilt these switches, but you need special material for the diaphragm, and it is very tedious work.
Switches now run 'bout $20.

Good site, click on Docs and DL's when you get there, then look for troubleshoot PDF:
9013 FSG, FRG, FYG Square D Pressure Switches - Schneider Electric United States

SQUARE D PRESSURE SWITCH 80 - 100 PSI FHG2J27CP SQUARE D CPD


Edit:
Pokin around AMHD I found this, "KUDOS" to jlisenbe for the link.
How to adjust water pump pressure, pump cut-on pressure and pump cut-off pressure - private pump and well system do-it-yourself repairs

KUXJ

When replacing pressure switch be sure to turn off electric power to switch.


Wrap pipe switch mounted on with 3 wraps of Teflon tape.

Good luck

Chuck