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  1. #27
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    May 2010
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    You'll still get amp readings if motor is overheated until the insulation wears off and completely grounds

  2. #28
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    Aug 2010
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    It seems like a pretty good and quick initial test then. From we discussed, it just will not work if the blower is completely grounded. I wonder why more techs don't use this test more often as an initial, quick test.

  3. #29
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    May 2010
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    Sort of, it will not work if the blower has open windings, but are not grounded.

  4. #30
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    Aug 2010
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    Yes, wouldnt work with open windings. There has to be a flow of electricity.

  5. #31
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    Sep 2008
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    Western PA
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    jjrr007,

    Get yourself a non-contact voltage detector.

    Don't go cheap, buy a good one.

    This way, you can test for the presence of voltage with a meter that is designed for the purpose.

    Either that or use the meter that you already have rather than trying to force an iffy shortcut to work.

  6. #32
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    Sep 2008
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    Western PA
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    Quote Originally Posted by ZeroTolerance View Post
    You'll still get amp readings if motor is overheated until the insulation wears off and completely grounds
    You will get an amperage reading IF and ONLY if the motor is drawing current.

    We can talk all day long about shorted windings, open windings, thermal overloads and other such stuff and not cover every scenario that a technician could encounter in the field.

    Use the correct meter for the correct job. Learn to use it correctly and learn to interpret the readings it gives you correctly and you will be MILES ahead of the guy who is trying to cheat.

  7. #33
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    The point a tech nees to come away with from this thrread is that a test for voltage is the only way to confirm that power is available for the motor to use. An ammeter is not the correct "first" tool to reach for if the motor is not running.

    If the motor IS running, and you want to see if it is in specs, THEN check the current with an ammeter.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  8. #34
    Join Date
    Aug 2010
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    84
    Honestly, the situation I described in the attic (a few posts below) shook me a bit. When the electrcity arced between my leads, it narrowly missed my hand and my latern fell through the ceiling. I almost fell too.

    For some situations, like the one mentioned above, I would like an alternative way to test the electrcity to a blower. Would a non-contact voltage test work with an open or grounded blower? It seems like it should.

  9. #35
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    May 2010
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    1,295
    It will because your getting voltage to the motor. Just like an outlet; the circuit is not complete, but your non-contact voltage detector will still light up cause its getting power.

    We call them "Hot Sticks"

    And I agree JP, there are tons of different scenarios one can encounter and we simply can not list them all.

  10. #36
    Join Date
    Aug 2010
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    84
    The non contact voltage indicator works for me then for "attic situations" or if I can't get my leads to quickly test the voltage to the blower. It can detect the voltage as a quick test.

    I have the Field Piece HS36. It has non contact voltage indicator. I will see how well it works for this use. I didn't think of it using this test till it was mentioned in this thread Thanks for your help with this.

  11. #37
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    Nov 2006
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    Southeastern Pa
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    Quote Originally Posted by jjrr007 View Post
    The non contact voltage indicator works for me then for "attic situations" or if I can't get my leads to quickly test the voltage to the blower. It can detect the voltage as a quick test.

    I have the Field Piece HS36. It has non contact voltage indicator. I will see how well it works for this use. I didn't think of it using this test till it was mentioned in this thread Thanks for your help with this.
    Make sure you use a non contact detector that has a range similar to the expected voltage. I have two Fluke units. One goes up to 50 volts for low voltage use, the other is for line level voltage.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  12. #38
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    Feb 2009
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    Canada
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    Quote Originally Posted by jjrr007 View Post
    Honestly, the situation I described in the attic (a few posts below) shook me a bit. When the electrcity arced between my leads, it narrowly missed my hand and my latern fell through the ceiling. I almost fell too.

    For some situations, like the one mentioned above, I would like an alternative way to test the electrcity to a blower. Would a non-contact voltage test work with an open or grounded blower? It seems like it should.
    The non-contact probe can tell you if you have power but they are not 100% reliable. It might be good enough to indicate voltage for you to try and start a motor but do not bet your life on it. If you get a no voltage reading and want to handle bare leads use a real meter to test for voltage. Every electrician that I know who uses these testers will tell you they have had false no voltage readings.

    I understand the concept of how you wanting to use the amp meter as a no contact way to determine if you have voltage but as the others have said you really should use the right tool for the job. As you have found, doing things in a makeshift manner can be dangerous. I have a regular set of test probes that I use to measure voltage but I also have a couple pair of test clips to use to clip onto screws, terminals, IC test clips which I can clip onto a minimum of exposed wire coming out of terminals.

    I do not do residential equipment but do end up hanging of the end of a ladder, crawling over ceiling tile, been in all kinds of tight spaces measuring things. As you say time is money but the extra time you would take doing the job right can save your bacon. I take the time to give my probes a wrap of electrical tape if it seems that there is a possibility of shorting out one to ground or another phase. I will clip on a test clip to ground and use the other probe to look for voltage rather than trying to hold two probes, possibly the meter, myself on a ladder... you get the idea.

    I take a little extra time but it does keep me safe.

  13. #39
    Join Date
    Aug 2010
    Posts
    84
    You have a nice idea. Sometimes, I just hold one probe to the case and test with the other. I could clip it on instead of holding the probe to the case. Yes, the probes are in good shape, but it wouldn't hurt to wrap the handles with electric tape.

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