Page 2 of 2 FirstFirst 12
Results 14 to 18 of 18

Thread: fluke 116

  1. #14
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    31,726
    Post Likes
    Quote Originally Posted by pageyjim View Post
    When you used the continuity beeper and got a reading you correctly realized you had a grounded compressor. If you use ohms on that meter and get a reading does it mean you have a grounded compressor?
    If you have a reading of OL, you are above 40+ megohms and generally good to go.

    I have found that a reading of less than 24 megohms is cause for concern, especially if it is not climbing. This usually happens when the short has just begun, but it can sometimes be enough to trigger a trip on 480 volt equipment.

    When you initially connect to the terminal of a good compressor, the reading can sometimes rise because the circuit behaves like a capacitor, being charged by your meter. If it finishes with OL, it's good.

    The dead giveaway readings are generally below 1 megohm, which will display as hundreds of kilohms (kΩ). You can still have a short with 0-24 megohms. In that scenario, you can compare the suspected compressor to others of the same type and vintage...hopefully, in the same unit's alternate stage. I have had units where all three compressors read out as about 16 megohms, and they all ran fine. The actual shorted component was found elsewhere in the unit.

    HTH.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
    Member, IAEI

    AOP Forum Rules:







  2. Likes under pressure liked this post
  3. #15
    Join Date
    Jul 2010
    Location
    US of A
    Posts
    5,224
    Post Likes
    Quote Originally Posted by timebuilder View Post
    If you have a reading of OL, you are above 40+ megohms and generally good to go.

    I have found that a reading of less than 24 megohms is cause for concern, especially if it is not climbing. This usually happens when the short has just begun, but it can sometimes be enough to trigger a trip on 480 volt equipment.

    When you initially connect to the terminal of a good compressor, the reading can sometimes rise because the circuit behaves like a capacitor, being charged by your meter. If it finishes with OL, it's good.

    The dead giveaway readings are generally below 1 megohm, which will display as hundreds of kilohms (kΩ). You can still have a short with 0-24 megohms. In that scenario, you can compare the suspected compressor to others of the same type and vintage...hopefully, in the same unit's alternate stage. I have had units where all three compressors read out as about 16 megohms, and they all ran fine. The actual shorted component was found elsewhere in the unit.

    HTH.
    Good post and I agree with all of it. I hope the OP reads it. The purpose of my post was to find out what the OP thinks without spelling it out for him like you just did so well. From his response to my post I think he will be better informed now and possibly have a few more questions.
    Signature removed Violated rule #15

  4. #16
    Join Date
    Jul 2010
    Location
    in a service van down by the river...........
    Posts
    554
    Post Likes
    Quote Originally Posted by jbhenergy View Post



    Moral of my post is, look at the actual meter and not just listen for the beep....... It cost me a long walk up the steps to the 3rd floor to reset a breaker, and a 3 amp fuse.
    Thanks for the public service announcement.....

    It is post like yours that give ALL or us a chance to review and improve ourselves.....


    Sent from my iPhone using Tapatalk
    It's All about Heat.............................to a degree

  5. #17
    Join Date
    Jul 2008
    Location
    Denver, CO
    Posts
    4,330
    Post Likes
    Flukes don't show age accept in appearance. I still have and occasionally use my fluke 77 I got in school in 1995.

  6. #18
    Join Date
    Dec 2019
    Location
    Nampa, ID
    Posts
    8
    Post Likes
    The Fluke 116 is my meter as well. My background is more electrical engineering than HVAC.

    That said, long experience has taught about the possibility of oxidation on exposed circuit conductors used for continuity testing. Make sure your probe is clean and that you really are making solid contact on both test points. You can sort of dig the probe tips into the metal a little (quick and dirty) or use a q-tip and 99% isopropyl alcohol to clean the metal before testing. FWIW... Good luck.

Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •