Help: Wiring 220 bandsaw: 2hots+ground, no 'white' ?

Discussion in 'The Projects Forum' started by shockedmonkey, Jan 6, 2015.

  1. shockedmonkey

    Thread Starter New Member

    Dec 28, 2014
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    0
    I have a new bandsaw. Supposedly, it is pre-wired for 220, but it has no plug.
    At the bandsaw's switch, I clearly see 'green' affixed to the machine as a ground.
    To me, white/black 'look' like they're on a traditional on/off switch, just like I'd see regular 110 white/black.
    But - service guy says I can treat these as 2 hots.
    He says I can skip the NEMA 6-15 plug recommended in Instructions, instead just get plug to meet the NEMA 10/50R socket I installed, i.e. make the 3 arrows as I show in diagram.

    My mental model for 110 is: black-hot goes out to machine, white brings elec back to close circuit. Ground is back-up/safety.
    Now - he's telling me I have 2 hots + ground.
    Q1: I am novice - is this how 220 works?

    Q2: Any test I can do at the bandsaw's switch - to really know that black/white are connecting to the
    switch 'expecting' to be 2 hots?
     
    Last edited: Jan 6, 2015
  2. #12

    Expert

    Nov 30, 2010
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    Absolutely nothing wrong with that. If you want to be picky, wrap some red tape on each end of the white wire. In electrician-speak, that makes the wire red.
     
  3. wayneh

    Expert

    Sep 9, 2010
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    That's correct. Each is ±110V versus ground, but they are 180° out of phase with each other, so you get 220V when you use both together. When one is +110, the other is -110V.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It is just that a 3 wire cord is white/black/green, aimed at the 120v circuit without due regard for using 240v.
    As #12 mentioned, according to the code you should colour the termination points of the white to red if being picky.
    Disregard any neutral in your hookup.
    BTW when working with 240v in N.A. both lines should be switched AND/OR fused. Not just one conductor.
    Max.
     
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  5. shockedmonkey

    Thread Starter New Member

    Dec 28, 2014
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    Well - I guess my understanding of electricity/circuits is even worse than I thought.

    Wayneh's comment, and MaxHeadRoom's 'Disregard any neutral in your hookup' really zero in on my concern.
    I always saw 'white' as completing the circuit - so wanted the same for my 220.
    Will have to read/learn more !

    Thank you all for guidance - will wire things up tonight and try. Thanks again.
     
  6. #12

    Expert

    Nov 30, 2010
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    They are both switched as per drawing in post #1
    (Not a problem.)
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The N.A. supply is 240v from a 1ph centre tapped transformer, so the centre tap can be ignored for 240v use and only becomes relevant when using either of the 120v sides.
    Max.
     
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  8. wayneh

    Expert

    Sep 9, 2010
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    The guy that ran that wire used white because that's what he had easily on hand that met code. Nothing magic about the color. I would suggest that, in general, wire color can never be considered more than a guideline of how things are probably hooked up. I usually check to confirm, to remove all doubt.
     
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  9. #12

    Expert

    Nov 30, 2010
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    Absolutely. This goes to my number one rule: Never bet your life (that somebody else did the job exactly as you would expect him to). I even check the other end of 24 volt control wiring in case an amateur wired up the system.
     
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