Results 1 to 7 of 7
  1. #1
    Join Date
    Mar 2007
    Location
    Santa Rosa, CA
    Posts
    3,154

    Default Odd Conductor Insulation

    This is not necessarily a problem, but I have not run into anything that looks like this before. This is located in a distribution panel at the circuit breakers. The last fraction of an inch of some of the conductor insulation is clear. It does not look to be added-on, but I didn't actually try to separate. I suppose it could be the outer sheath of THHN


    Unfortunately, I did not get the brand of the cable.


    I was just curious. Has anyone noticed anything like this in the past?072619 036a.jpg

    Similar Threads:
    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Inspection Referral
    Department of Redundancy Department
    Supreme Emperor of Hyperbole
    http://www.FullCircleInspect.com/

  2. #2
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Odd Conductor Insulation

    What that first looked like to me was the outer clear plastic of THHN/THWN insulation.

    My first guess was that the wire was stripped back and, somehow, the outer covering 'stretched out' over the inner insulation.

    But ... when I was zoomed in on it to see it better, the jagged cut end of the clear covering matches the nicks in the copper conductor - which is not to be nicked like that (the conductor is susceptible to cracking and breaking if nicked).

    Any other ideas about what is shown?

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  3. #3
    Join Date
    Mar 2007
    Location
    Santa Rosa, CA
    Posts
    3,154

    Default Re: Odd Conductor Insulation

    Quote Originally Posted by Jerry Peck View Post
    What that first looked like to me was the outer clear plastic of THHN/THWN insulation.
    My first guess was that the wire was stripped back and, somehow, the outer covering 'stretched out' over the inner insulation.
    But ... when I was zoomed in on it to see it better, the jagged cut end of the clear covering matches the nicks in the copper conductor - which is not to be nicked like that (the conductor is susceptible to cracking and breaking if nicked).
    Any other ideas about what is shown?
    Thanks Jerry,

    I guess I didn't post the really close-up image. I thought I did. And the real close-up doesn't show the nick.

    Someone else guessed that it was a dull wire stripper that didn't cut through the outer clear nylon but managed to pinch-off/separate the inner PVC.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Department of Redundancy Department
    Supreme Emperor of Hyperbole
    http://www.FullCircleInspect.com/

  4. #4
    Join Date
    Mar 2007
    Location
    Plano, Texas
    Posts
    4,245

    Default Re: Odd Conductor Insulation

    Yep, I have found clear outer covering many times.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  5. #5
    Join Date
    Mar 2009
    Location
    Colorado Front Range
    Posts
    684

    Default Re: Odd Conductor Insulation

    I missed this in my intermittent browsing and picked it up in Brian's e-mail.

    It has been my experience that some types of older insulation will turn clear after repeatedly being very warm or hot. It seems that the required temp to start this process is very specific and hence the almost immediate change from color to clear. The color to clear appears not to be exactly a straight line toward the top of the picture and this is what I typically see.

    While the nick in the copper is a bad practice it doesn't appear to have caused this. I'd be all for checking the terminal screw on the breakers to see if they are snug. It's almost a sure bet they're not torqued. It does look to me like the exposed copper has been heated a bit but the picture makes it hard to tell for sure.

    I had a job once where the homeowner had run a #14 NM to a dryer using the ground as a neutral and the neutral as a second hot wire. Then he added a washing machine to the circuit using the ground wire and the white wire. The cable had been so hot that the insulation on both the black and white conductors AND THE SHEATH was clear and you could see the copper through the sheath. There was a bit of color in the sheath and conductors near the few staples present. Amazing stuff. The insulation was drooping in only one place and wasn't charred anywhere, or brittle.

    All fed from a 50 AMP 2 pole breaker BTW.

    Occam's eraser: The philosophical principle that even the simplest solution is bound to have something wrong with it.

  6. #6
    THOMAS HORNE's Avatar
    THOMAS HORNE Guest

    Default Re: Odd Conductor Insulation

    The problem that I see is that the insulation is stripped too far back on the conductor. Best practice is that it be stripped no longer than needed for the conductor to be completely in the terminal without any insulation under the terminal pressure plates nor inside the connector itself. I would bet a pretty penny that those terminations were not made in accordance with instructions included in the listing or labeling.

    --
    Tom Horne


  7. #7
    Join Date
    Aug 2019
    Location
    CA
    Posts
    1

    Default Re: Odd Conductor Insulation

    Quote Originally Posted by Gunnar Alquist View Post
    This is not necessarily a problem, but I have not run into anything that looks like this before. This is located in a distribution panel at the circuit breakers. The last fraction of an inch of some of the conductor insulation is clear. It does not look to be added-on, but I didn't actually try to separate. I suppose it could be the outer sheath of THHN


    Unfortunately, I did not get the brand of the cable.


    I was just curious. Has anyone noticed anything like this in the past?072619 036a.jpg
    I ran into that stuff when I used to do industrial controls. The clear coating is Teflon. It's chemical resistant and makes it easy to pull through long runs of conduit.


Bookmarks

Posting Permissions

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