Tools you need
- Flathead screwdriver (to remove the switch cover)
- Adjustable wrench (to turn the nuts)
- Non-contact voltage tester
- A working pressure gauge, ideally one you can watch while the pump cycles
Step-by-step adjustment
- Record your current settings first, before opening anything: run a faucet until the pump starts and watch the gauge for the pressure at which it kicks on (cut-in) and shuts off (cut-out). Everything stays closed and powered for this step — it is just reading the gauge.
- Shut off power at the breaker feeding the pump circuit and confirm with a voltage tester before removing the switch cover.
- Remove the cover and identify the two nuts: the larger nut sits on the larger spring (range nut), the smaller nut on the smaller spring (differential nut). Never restore power while the cover is off.
- Adjust the range nut first. Turning it clockwise raises both cut-in and cut-out together; counterclockwise lowers both. Roughly 3.5 clockwise turns raises both settings about 10 psi, per Square D's own specifications as documented by InspectApedia (see Sources).
- Adjust the differential nut second, only if you need to change the gap between cut-in and cut-out. Clockwise raises cut-out only, widening the differential; counterclockwise narrows it. Professionals on terrylove.com note the differential usually should not be pushed much below roughly 20 psi on a standard residential switch — pushing it lower is a common way to induce short cycling rather than fix it.
- Replace the cover, restore power, and let the pump run a full cycle while you watch the gauge. Repeat steps 4 and 5 in small increments until you hit your target cut-in and cut-out.
- Reset the tank precharge to 2 psi below your new cut-in pressure, checked with the tank fully drained and the pump powered off — this is the manufacturer rule from the Amtrol Well-X-Trol manual (see Sources). Skipping this step is a common reason a freshly adjusted switch still cycles oddly.
Turn counts for common conversions
| From | To | Approx. range-nut turns |
|---|---|---|
| 20/40 psi | 30/50 psi | ~3.5 turns clockwise |
| 30/50 psi | 40/60 psi | ~3.5 turns clockwise |
| 40/60 psi | 30/50 psi | ~3.5 turns counterclockwise |
Treat these as a starting estimate, not a precise spec — verify against your gauge after every adjustment, in quarter- to half-turn increments once you're close. Before changing ranges, read the 30/50 vs 40/60 comparison to confirm your pump and plumbing can handle the target pressure.
When adjustment won't fix it
If the cut-in point is stuck and won't move even after the range nut is turned — a real case reported on terrylove.com involved sediment or mineral buildup under the diaphragm holding cut-in at 34 psi no matter how the nut was turned — the switch itself may need replacing rather than further adjustment. See our troubleshooting guide and the adjust vs. replace guide before you keep forcing a stuck nut.