Help: 'voltage leak?' within my 220-line or within my bandsaw?

Discussion in 'The Projects Forum' started by shockedmonkey, Jan 11, 2015.

  1. shockedmonkey

    Thread Starter New Member

    Dec 28, 2014
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    When I plug in my new 220V bandsaw - I feel serious 'tingling' if I touch the saw's table.
    I'm told I have a 'voltage leak'? Is this what a 'voltage leak' feels like?

    I just wired-up both the saw and the 220 outlet w/ help from a prior thread titled:
    Help: Wiring 220 bandsaw: 2hots+ground, no 'white' ?

    My first Conjecture: Things are wired-up correctly. My problem is a singed/damaged part of the 220-line.
    When making the 220-wall outlet, re-purposing an old kitchen oven line I had in my crawlspace,
    I had noticed that the metal cladding is singed-thru at a point in the run between my main panel and my outlet.

    Observations:
    My bandsaw runs. It may be running below full bore - unclear.
    Tingling is present when bandsaw is off, didn't check if same tingling when machine's on.

    I'm a novice - Does below approach make sense to test the 220-line as my first conjecture ? :
    Get a volt-meter.
    Test 1: Use the ground-wire of a nearby 110 outlet. With saw plugged in, put 1 probe on saw's table-top and other connected to 110-outlet's ground. I expect to register some voltage - verifying I have a problem.

    Test 2: One-by-one, probe each of the 3 wires of the 220 line, again paired with the 110-outlet's ground.
    I expect to see some voltage thru my 220-white to 110-outlet ground, when it shouldn't have any.
    Then I'll know my problem is this 220-line. If no voltage, then my problem is within the saw.

    There is no use in tests amongst the 3 wires of my 220V outlet: i.e. Red to White(ground), and the Black to White(ground). Correct?

    If 220-line is my problem (and not the saw) - Then: I try cutting out the 'singed' part of the 220-line.

    Thank you for guidance.
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    I think you should check that the PE - protectione earth conductor is properly connected. That is if you are using a three pronged socket, otherwise the saw might be deffective.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Definitely a sign the Earth Ground is missing or defective in some way.
    Max.
     
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  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    It is time to call an electrician. A $120 Bill for a service call is much cheaper than a funeral.
     
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  5. #12

    Expert

    Nov 30, 2010
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    and we are talking funeral quality here. Get it right or die trying!
    Wait...get it right, even if you have to hire somebody.
    That's better.
     
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  6. ebeowulf17

    Active Member

    Aug 12, 2014
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    Step 1: unplug the bandsaw until you have this all sorted out.

    Step 2 should almost certainly be calling an electrician.

    If you want to investigate further, I'd check the outlet and the saw separately.

    Re the outlet, you're right to think that there should be 0 volts between the ground from your 110V outlet and the ground from your new 220V outlet. If you find voltage between them, you have a seriously flawed ground (and almost certainly should call an electrician.)

    As for the two hot wires on your 220 line, there's a 90%+ chance that they should each read 110V to ground, but have opposite polarity so there's 220V between them. It's unlikely that you have 220V leg and a neutral, as your earlier test proposal suggests.

    [EDIT: After re-reading your other thread again, it occurs to me I may have misunderstood your meaning on the outlet testing, due to the strange color coding on both ends. The building ground should really be green, not white, although function would be far more important than color here!]

    As for the saw, you can use your meter to do some continuity tests between the various wires. With the saw unplugged (no power anywhere) and the power switch on, you should read continuity (close to 0 ohms) between your ground wire and just about any exposed metal surface. You should read infinite resistance (might read as OL) between each hot wire and the ground, and between the two hots you'll probably get an ohm reading corresponding to the motor's resistance.

    The last reading could be misleading depending on internal electronics, but if the grounding continuity isn't good or if there's any continuity between either hot and ground, you've got serious internal problems.

    Sorry this so long. You should really get a professional involved. But if you choose not to, at least do your testing in the least dangerous way possible - don't leave a machine with obvious wiring problems hooked up!!! Unplug, then figure things out.
     
    Last edited: Jan 12, 2015
  7. #12

    Expert

    Nov 30, 2010
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    We haven't killed anybody yet...that we know of...but we worry about it to an appropriate amount.
     
  8. ebeowulf17

    Active Member

    Aug 12, 2014
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    It's good to find that healthy amount of worrying - not enough to keep people from trying things, but enough to keep them alive. Keep up the good work!
     
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  9. sirch2

    Well-Known Member

    Jan 21, 2013
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    If it's new as you say, return it (may be not easy with a large item like a bandsaw) or get the supplier to send someone out to fix it.
     
  10. ebeowulf17

    Active Member

    Aug 12, 2014
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    Great idea if the problem is the saw itself. From what I'm reading here, it sounds more likely to be a problem in the building wiring.

    I suppose the supplier's service tech could come out and determine that, but they probably wouldn't fix anything if it were the building wiring and not the saw.
     
  11. shockedmonkey

    Thread Starter New Member

    Dec 28, 2014
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    Thank you all for guidance.
    I have machine unplugged and the 30Amp breaker off.

    Tonight - I will try what ebeowulf17 says:
    Re the outlet, you're right to think that there should be 0 volts between the ground from your 110V outlet and the ground from your new 220V outlet. If you find voltage between them, you have a seriously flawed ground (and almost certainly should call an electrician.)
    I think even just bringing my Greenlee voltage sensor near the 220-V's White will show I have the bug as I'm guessing.

    Will try this tonight + report back. And - won't mess with the machine at all for now....
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Ideally it should be tested with a dual type megger, resistance and insulation type.
    This give a true answer as to what is going on.
    Max.
     
  13. #12

    Expert

    Nov 30, 2010
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    Max, I agree. A Megger would be ideal, but most people don't have a Megger, and a tingle level of leakage is easily readable on a $10 meter. That and $10 worth of brain power will fix this right up.

    Right now, we're trying to install $10 worth of brain power in a shocked monkey. :D
     
  14. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The leakage is detectable without the meter apparently !:(

    But a $10.00 meter is not necessarily going to definitively give him confirmation of the integrity of the cure?
    Max.
     
  15. #12

    Expert

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    What can I say? I bet I could find a faulty earth ground for a 230 VAC circuit with a $10 Harbor Freight meter. Then I could measure AC current leakage into the bond wire. If the insulation in the motor is weak, it will either work, or not work, or burn up the motor windings, or pop a circuit breaker. All I care is that the human is safe. We should all have our motors able to pass an insulation test that applies thousands of volts to windings that only need to survive about 350 volts peak. When Harbor Freight starts handing out $10 Meggers, all of us will feel more confident. Until then, most of us will have to settle for using a proper bond to earth ground to keep us safe on a personal level.
     
  16. shockedmonkey

    Thread Starter New Member

    Dec 28, 2014
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    Well - I tried checking voltages of my 220 line. I put 1 probe on the ground of my nearby 110 outlet. Then- 1 probe on the 220's red: I get 120+ reading.
    On 220's black: again 120+ reading.
    On 220's white: Nothing. So - I hoped to see voltage in this white - but since I don't see anything - I guess I conclude I have a problem
    within my bandsaw.
    May take me weeks to get an electrician - but will report back my findings to close the loop.

    Thank you again for guidance.
     
  17. #12

    Expert

    Nov 30, 2010
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    You are not going to measure voltage on the earth ground wire with the leaky thing (bandsaw) unplugged, so you have not proven anything. Turn off the power and measure the ohms from the earth ground of the 230 volt circuit to the earth ground of the 120 volt circuit. That should be just a few tenths of an ohm.

    For a double check, any water pipe that is continuous metal until it goes underground or gets a wire connected to the breaker box from the pipe. That is an earth ground.

    Personally, I can do this with a damp concrete floor, but I'm not even going to try to force several years of experience and good judgement into your head today.
     
  18. ebeowulf17

    Active Member

    Aug 12, 2014
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    #12 beat me to it on testing the outlet grounds for resistance, not just voltage. Good call.

    Also, if you've got a meter, why not try the continuity (resistance/ohms) checks on the saw? You might not find anything conclusive with the limited tests described above, but you also might find a smoking gun. As long as the saw is unplugged, there's zero risk in testing it.
     
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  19. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You would not normally have a Neutral (white) ran to a 240v saw, if there is a white present it may be just fed up to the saw or outlet, but unconnected in the panel or neutral source itself.
    What is the nature of the motor? Induction or Universal (brushes). If the motor is un-grounded and/or the table you get the tingle on is also not bonded to earth ground, it could be a Universal motor has leakage through the brush carbon that builds up.
    First apply power to the saw and test using an AC meter on voltage from the Table to a known ground, if it registers a voltage, see if it will also sustain a ground current by using a 120v test lamp from the Table to known earth ground.
    If the lamp lights or glows, then the earth ground conductor between panel a saw is definitely missing or open.
    Max.
     
  20. #12

    Expert

    Nov 30, 2010
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    I could have sworn there was a good drawing of this circuit attached yesterday. :confused:

    We went through the part about using a black/white/green SJ cord for 230 VAC by adding red tape to both ends of the white wire.

    Wrong thread? Senior moment?
     
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