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  1. #11
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    Default Re: Question on 3-phase well pump

    Switching any two legs on a 3 ph motor changes direction.
    The shape of the impeller causes it to work better in one direction AND as stated can unscrew it from the shaft because a lot of motors have left hand threads holding it on.

  2. #12
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    Default Re: Question on 3-phase well pump

    Need more info. Is the pump | Power, 480/277Y - 208/120Y VAC, 3-phase

    Don't just switch legs till you know what you have. If you have 480 - ONE OF YOUR LEGS is 240 and the other two legs are 120. switch two 120 legs and you still have the same problem - obviously.

    A 3-Wire System

    Many people think that the 3-wire system refers to a "three-phase" power system, but this isn't the case at all. The three wires refer to the three colored wires that come from larger submersible pumps. These are typically yellow, black and red wires coming from the well pump to the control box. The control box is the central wiring point for this system, and it's where the three colored wires come in, as well as where the incoming power from the pressure switch are also connected. The 3-wire system is necessary for larger pumps because these pumps require a special "start-up" process.

    The red cable only gets energized temporarily until the pump comes up to speed
    Then the control box switches operating power over to the black wire
    The yellow wire is the "common", not to be confused with the green "ground" wire that must be connected to your main power ground connection.

    The 3-wire system isn't much more complicated than the 2-wire system, but it does require that the correct wires get connected to the correct terminals inside the control box.


    Some diagrams
    http://greenroadfarm.com/wells.html

  3. #13
    Platinum Member TheGoose's Avatar
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    Default Re: Question on 3-phase well pump

    3-phase pumps/motors will run backwards and they will still pump water even running backwards. Like was stated, just reverse the leads ( any 2 ) to reverse the direction.
    Kubota L3400 HST with FEL, R1 Tires, 4x4
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  4. #14
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    Massey

    Default Re: Question on 3-phase well pump

    Quote Originally Posted by Cat_Driver View Post
    Need more info. Is the pump | Power, 480/277Y - 208/120Y VAC, 3-phase

    Don't just switch legs till you know what you have. If you have 480 - ONE OF YOUR LEGS is 240 and the other two legs are 120. switch two 120 legs and you still have the same problem - obviously.

    Some diagrams
    Green Road Farm ~ Submersible well pump installation & Troubleshooting
    3 phase 480v wired "Y" as you show always has 277 volts on each leg to ground. I think you are confusing something else, as you mention 240v and 120v.
    3 phase and "3 wire single phase are unrelated. If he really has 3 phase, he would need a special 3 phase feed, or a 3 phase generator, or a VFD.
    Also pump type/design is what determins if they move water while going backwards, not wheather it's a 3-phase motor or not.

  5. #15
    Gold Member caver's Avatar
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    Sikeston, MO
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    Fisher Price, toddlers first tractor.

    Default Re: Question on 3-phase well pump

    Quote Originally Posted by podagrower View Post
    If you have Delta 3 phase, you need to be careful which 2 legs you swap. If there are single phase controls, and you put them on the high leg, you will be buying new controls.

    It doesn't matter. Line voltage control is not common but possible in a rural area. You use L1-L2 for your starter. 99.9% of installations today
    will use a control transformer for 120V control wiring.
    Claude farmer

  6. #16
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    Default Re: Question on 3-phase well pump

    I'm thinking it's more likely he's got a standard single phase, 220, capacitor start pump where they have the caps in a small box mounted up top and 4 wires going down to the pump motor.
    I'm with him, one wire common (YL), one wire for run (BLA), one for the start cap (RD) and one for ground (GR) Google Image Result for http://www.make-my-own-house.com/images/controlbox.jpg ....Mike

  7. #17
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    NC
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    Kubota Grand L3830

    Default Re: Question on 3-phase well pump

    I think the poster should find a electrician familiar with 3-phase wiring and pumps. Pumps cost money, control panels cost money, and labor to remove and install a pump is expensive. Learning on the job can get expensive fast. A fifty gallon per minute pump sounds very commercial to me. 3-phase wiring also sounds commercial to me. I don't think I would trust the installation and wiring to someone who slept in a Holiday Inn Express last night as the commercial goes.

  8. #18
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    John Deere 1070

    Default Re: Question on 3-phase well pump

    a quick but not necessarily absolute way of telling if it is in fact a 3 phase motor is to take the 3 non-ground wires (from the motor) and test continuity between them. Any of the 3 possible combinations of 2 wires should give you approximately the same resistance reading (within 10%).

  9. #19
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    Massey

    Default Re: Question on 3-phase well pump

    Had to think for a second, but yes you're right. I'm not used to back yard mechanic troubleshooting shortcut methods when it comes to 3 ph. Normally, If you have 3 ph, you have trained employees. That's why I wonder if it's 3 ph at all. I ve seen 'advice' given on this forum that decribes 240 residential, as 2 phase 120.

  10. #20
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    John Deere 1070

    Default Re: Question on 3-phase well pump

    Quote Originally Posted by DarkBlack View Post
    Had to think for a second, but yes you're right. I'm not used to back yard mechanic troubleshooting shortcut methods when it comes to 3 ph. Normally, If you have 3 ph, you have trained employees. That's why I wonder if it's 3 ph at all. I ve seen 'advice' given on this forum that decribes 240 residential, as 2 phase 120.
    Oddly enough, I am a trained employee. This is a quick diagnostic that I use sometimes. Easy to tell if a motor is bad, but can't tell you that a motor is good. Also is a quick way to check the wiring to the motor from a contactor.

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