Square D Control Switch with Automatic Low Pressure Cut Off

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by RayMan, Feb 12, 2010.

  1. RayMan

    RayMan Shared Well Services

    Jan 23, 2010
    Self Employed
    Square D offers a pressure control switch that can include an automatic pump cut off in the event the pressure drops 10 psi below the cut in pressure. Will the cut off option provide reasonable protection for the pump against dry well pumping conditions?

    Is 10 psi below the normal cut in experienced with other water usage conditions that would trip the control switches automatic cut off making the switch a nuisance having to manually reset the switch?

    Thanks Again For Your Help & Experience!! :)
  2. nhmaster

    nhmaster Master Plumber

    Jul 30, 2008
    Tech. Instructor
    S. Maine
    Yes it will and yes you should.
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  4. thassler

    thassler Member

    Dec 5, 2006
    Systems Analyst
    Just something to keep in mind is that the low pressure cut-off switch only works if water is being used. For example, If the pump is refilling the pressure tank but the well goes dry before cut-off pressure is reached and no water is being used, the pump will continue to run.
  5. ballvalve

    ballvalve General Engineering Contractor

    Dec 28, 2009
    "retired" and still building and troubleshooting
    northfork, california
    Rare event combination, and almost no nuisance trips at all. Not many return calls for the pros if they use them, which few seem to do.
  6. Akpsdvan

    Akpsdvan In the Trades

    Dec 29, 2009
    Business owner/service and sales
    As a well driller told me about this kinda a switch, poor mans low water protection.. It will work but the low water protection of some thing like a Coyote would be better.
  7. Jay J

    Jay J New Member

    Sep 1, 2013
    Could you please explain? I have a friend who has this pressure switch on a pump that pulls water from an atmospheric tank. The assumption was that if the tank ran dry, when the pressure dropped 10 PSI below the cut-in pressure, the pump would stop. The complaint is that the pump keeps running and your info confirms that, but I want to understand why.

  8. craigpump

    craigpump In the Trades

    Apr 12, 2012
    Self employed water system tech
    Spend the money for a Pump Tek, they are reliable and less of a pain in the a$$ because they reset themselves.
  9. DonL

    DonL Jack of all trades Master of one

    Mar 30, 2011
    Rocket Scientist
    Houston, TX
    I know the well guys do not like them, the lever hurts their thumb waiting for the tank to get up to 10psi.

    That lever does hurt.

    I made a Block of wood, that slides over the lever to hold it open while I just watch the pressure, and my thumb and fingers don't hurt.

    They work OK, but can be a PITA waiting for that first 10psi.
  10. valveman

    valveman Cary Austin Staff Member

    Mar 15, 2006
    Pump Controls Technician
    Lubbock, Texas
    Low pressure cut-off switches only shut the pump off when the system pressure is lower than the ON setting. If you have a sprinkler or something running for long periods of time, when the storage tank is empty, the pump can’t keep the pressure up and the system goes off on low pressure. But if you only flushed a toilet the pump will start at 40 PSI, and the toilet fills quickly, so there is not more water being used. The storage tank is empty so the pump cannot fill the pressure tank to 60 PSI and shut off the pump. So the pressure just hovers around 50 PSI, and the pump doesn’t shut off until it melts down and trips the breaker.

    The only thing a low-pressure cut off switch can do reliably is to shut the pump off if there is a major line break. It is really not dependable for a Dry Well condition or a small leak in the mainline.

    Devices like the Cycle Sensor http://www.cyclestopvalves.com/prod_sensor.html look at amps not pressure to determine if the well is dry. This is more reliable and can be used with the built it timer to automatically restart the pump after the well has had time to recover.
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