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Thread: 115 Volt or 230 Volt. How Do I Know?

  1. #1
    Join Date
    Jul 2003
    Fredericksburg, VA

    115 Volt or 230 Volt. How Do I Know?

    OK...I'll admit it. I don't know how to tell the difference.

    I'm installing a new pool pump motor. I've got it all wired, the impeller is good to go, etc. The only thing I'm not sure about is this: There is a toggle on the motor that needs to be set to 230V or 115V...depending on what is running to it. The wire is connected to a 20 amp double-post breaker in the box. How can I determine if this is 115V or 230V?

    If this is something I should just inherintly know....please forgive me and don't laugh too hard.

    - Keith
    "Listen, here's the thing. If you can't spot the sucker in the first half hour at the table, then you ARE the sucker. "

  2. #2
    Join Date
    Feb 2003
    Leesville, SC

    If it is fed from a double breaker, two breakers tied together, it should be 220 volts.
    Army Veteran 1968 - 1970
    NRA Lifetime Member
    I Support the Second Amendment of the US Constitution

  3. #3
    Join Date
    Feb 2003
    Griswold Connecticut

    No it's not something that is intuitive, nor is it a male only gene.
    If by the breaker, you mean the breaker in the main service panel, and not a disconnect panel, then the breaker you are describing is "most likely a 240 breaker. The breaker will be occupying 2 slots,and will be physically larger than a single 115 breaker unless you are dealing with a tandem breaker., of which there are a myriad of configurations.

    There are some warning bells going off for me though. Most importantly I have never seen a breaker that didn't have some form of label on it that clearly identified what it was, who made it, voltage and amperage rating,UL sticker etc.. This may be the case because what you are looking at could be a molded case two pole disconnect switch. If wired for 220 it disconnects both of the hot legs. if wired for 120 it could be set up to disconnect the hot and the neutral. Since it provides power to a pool pump, it is hard to determine exactly what the code requirements are for your area, an what may have been installed.
    A picture would really help folks, and no one should be laughing.
    Last edited by Mike Cutler; 09-03-2009 at 5:06 PM.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  4. #4
    A volt meter should remove all doubt. Test between both leads that are not ground - It should read 220v between those two leads, if it's a 220v circuit.
    Jason Beam
    Sacramento, CA

  5. #5
    Join Date
    Mar 2003
    Monroe, MI
    If its a dual pole breaker, should be 220. Assuming someone knew what they were doing when the wired it. Or some hack previous homeowner could have lifted one of the wires off the breaker, attached it to the ground or neutral buss in the panel, and made themselves a 110 circuit, proud of saving themselves the $6 the breaker would have cost. I saw the opposite in my old house--two single pole breakers used to create a 220 circuit.

    It sounds like there was an old motor? Could you tell from that?

  6. #6
    Quote Originally Posted by Keith Starosta View Post
    OK...I'll admit it. I don't know how to tell the difference.
    Kieth, go with Jason's suggestion. Don't mess with "it should be," that's some poor advice.
    Dave J
    Forums: Where all too often, logic is the first casualty.

  7. #7
    Join Date
    Jun 2007
    Wichita, Kansas
    +1 for putting a voltmeter on it. Remove all doubts.
    Tom Veatch
    Wichita, KS

  8. #8
    Quote Originally Posted by Tom Veatch View Post
    +1 for putting a voltmeter on it. Remove all doubts.
    Also removes doubts about faulty equipment, suspect outlets, DIY wiring jobs, and in my most recent case, ceiling fan installations.

    Get a voltmeter.
    Deflation: When I was a kid, an E-ticket meant I was about to go on the ride of my life. Today, an E-ticket means a miserable ride.

  9. #9
    If the elect. work was done by a real electrician the color of the wires from the breaker to the motor will tell you, There will be 3 wires, One is green, That's the ground, if the other 2 are red and black it's 230v single phase, That equals 2 hot legs and a ground, 110v will be either one red or black, one white and one green, The white is a neutral, So you have one hot leg, one neutral and one ground. if there are 4 wires (which I doubt) then you are dealing with a 3 phase system, Hope this helps

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