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Thread: 240V pump switching

  1. Back To Top    #1

    Join Date
    Mar 2015
    Plano, TX

    240V pump switching

    I am not yet sure if my pumps are 120 or 240 volt, they can be wired for either. Currently there are two mechanical timers which I would like to replace with a single digital timer. I ordered an Intermatic ET1125C which has two outputs - it can either run as two independant SPST switches, or a single DPST switch. When I ordered it I had just assumed the pumps were 120V, but after notice that they can be configured either way I'm now wondering if they're 240. If they are 240, is it safe to use the timer to only switch one hot wire to each motor? There is a master switch next to the timer that cuts all power to everything, so it can still be safely shut off at the equipment. However, with the timer only switching one hot wire, there is still 120V potential at the motors.
    1982 built 15K? gallon IG gunite/plaster, DE filter, Pentair Challenger 1.5HP pump, Polaris 280, Pentair LA01N booster pump, 3-8' with diving board, K-2006 test kit

  2. Back To Top    #2

    Re: 240V pump switching

    240 volt switches should be double pole. You should get the correct timer for your voltage. If you're powering a booster pump, the timer needs to cut power to the booster when the power to the main pump is off.

  3. Back To Top    #3
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: 240V pump switching

    Switching only one leg of a 240 volt circuit is allowed, though not recommended. It is fairly common to see for exactly the reason you are thinking about it, many of the digital timers only provide for switching one leg of the circuit.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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