How to Adjust a Square D Well Switch

Written by g.k. bayne
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Square D manufactures a pressure switch for well pump systems. The pressure switch is physically attached to the plumbing piping near the water pressure tank. There are two adjustment nuts on the Square D switch. The larger 1/2-inch-diameter nut is for the operational "cut in" and "cut off" of the pump. The smaller 7/16-inch-diameter adjustment nut increases or decreases the span of the cut-in and cut-off setting. In most cases, only the 1/2-inch nut needs to be adjusted to increase or decrease the water system pressure.

Skill level:

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Things you need

  • Pliers
  • 1/2-inch end wrench
  • 7/16-inch end wrench

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  1. 1

    Shut off the electrical power to the pump system by switching off the circuit breaker or pulling the fuses.

  2. 2

    Fit the jaws of the pliers over the plastic cover nut that holds the protective cover onto the metal housing of the pressure switch. Turn the nut in a counterclockwise direction to remove it.

  3. 3

    Place the 1/2-inch end wrench over the larger nut. Turn the wrench in a clockwise direction to raise the overall cut-in and cut-off water pressure setting. Moving the wrench in the opposite direction will lower the cut-in and cut-off pressure. Typically, low-pressure systems operate at 9.07 Kilogram per square inch (psi) cut-in and 40-psi cut-off. Higher-pressure systems use a 30-psi cut-in and a 50-psi cut-off.

  4. 4

    Adjust the span of the pressure range by placing the 7/16-inch wrench over the smaller adjustment nut. Turning the wrench in a clockwise direction will raise the cut-off pressure only, increasing the span from the cut-in point. Moving the nut in a counterclockwise direction decreases the span, bringing the cut-off pressure closer to the cut-in point. Do not lower the cut-off pressure too much, as the pump may not shut off.

Tips and warnings

  • Do not adjust the cut-off pressure above 70 psi. Many home water systems cannot handle this high pressure, and damage may occur to faucet fixtures and plumbing joints.

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