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Thread: Intermatic T-103

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    guamguy's Avatar
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    Intermatic T-103

    I've got a quick question about an Intermatic T-103. Currently, my pool pump and spa pump are hooked up to this timer. Both the pumps are running on 240 volts, and only one leg of the 240v for each pump runs through the timer. Is this correct? The T103 is a DPST switch, so one leg to each pump is switched by the timer, and the other is constantly hot. I've had the house/pool for a year with no problems with this setup, just wondering if this is the right way to do this
    12,800 gallon IG plaster kidney-shaped pool, waterslide, 800 gallon spa.
    1HP 2 speed Sta-Rite pool pump, 1.5 HP Sta-Rite spa jet pump. 2 skimmers, 1 main drain
    Purex-Triton TR-60 325 lb.sand filter. 2" Plumbing, Intex SWCG, TF-100 test kit.
    Link to pics of my pool! http://www.troublefreepool.com/my-oasis-t26558.html

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    Mod Squad Bama Rambler's Avatar
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    Re: Intermatic T-103

    It won't hurt anything to do it that way.

    The proper way is to switch both legs but since it's running both pumps switching one leg of each is ok. Just remember (and never forget) that there's still voltage going thru the motor windings at all times unless the breaker is off.

    The best way to do it would be to have two timers but with things being things, we sometimes have to do what we have to do.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Ohm_Boy's Avatar
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    Re: Intermatic T-103

    Wow. While it works, it is not correct. As Bama points out, there is always one side of the line connected to the equipment all the time. That means that there is line voltage present through the wire to the motor, the motor windings, and the wire back from the motor, all the way up to the "open" timer connection all the time. You could actually get shocked from the terminal on the timer that is 'open', as it is at 120 volts as measured from the neutral or ground. And it is happening on both of your motors.

    This is one of those things that wouldn't pass an inspection, and unfortunately, as Bama also mentioned, is sometimes done as "what we need to". In theory, it works, but it is only safe as long as nothing fails.

    It would be better if the motors were connected in parallel and both legs were switched.
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    guamguy's Avatar
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    Re: Intermatic T-103

    I knew something wasn't quite right when I looked at this I knew the windings were still hot when the timer was off, this is my first pool and I wasn't sure if this was common practice. I keep the spa pump breakers off anyway, no reason to run it every time the pool pump runs. No wonder why the previous owners thought the power bill was really high I figured it's a good time to do some rewiring, since I'm swapping out my single speed motor with a 2-speed today. Guess I'll see if I can find a DPST switch for the spa pump and redo the timer to switch both legs of the 230v for the pool pump. Thanks for the advice, and I'll let you all know how the motor swap goes
    12,800 gallon IG plaster kidney-shaped pool, waterslide, 800 gallon spa.
    1HP 2 speed Sta-Rite pool pump, 1.5 HP Sta-Rite spa jet pump. 2 skimmers, 1 main drain
    Purex-Triton TR-60 325 lb.sand filter. 2" Plumbing, Intex SWCG, TF-100 test kit.
    Link to pics of my pool! http://www.troublefreepool.com/my-oasis-t26558.html

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    guamguy's Avatar
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    Re: Intermatic T-103

    Just a quick update, the motor swap is complete. Only took about an hour, and the toughest part was working with the wiring! That 12ga solid copper don't bend real easy!
    12,800 gallon IG plaster kidney-shaped pool, waterslide, 800 gallon spa.
    1HP 2 speed Sta-Rite pool pump, 1.5 HP Sta-Rite spa jet pump. 2 skimmers, 1 main drain
    Purex-Triton TR-60 325 lb.sand filter. 2" Plumbing, Intex SWCG, TF-100 test kit.
    Link to pics of my pool! http://www.troublefreepool.com/my-oasis-t26558.html

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