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#185812 - 03/29/09 04:44 PM Brittle THHN insulation on NM-B conductors  
newsgraphics  Offline
Member
Joined: Nov 2005
Posts: 11
California
Last night I was installing a ceiling fan in our relatively new house (built in 2005). It was pre-wired for ceiling fans, so this should have been an easy installation. However, after twisting the wire nut onto two of the conductors, I noticed that the insulation on the THHN jacket had literally split and exposed the bare copper wire!

Admittedly, I did crank those wire nuts on tightly, but I have never had a problem with insulation splitting like this before. I ended up having to cut it back about two inches. Has anyone else had this occur before?


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#185813 - 03/29/09 05:17 PM Re: Brittle THHN insulation on NM-B conductors [Re: newsgraphics]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,142
Estero,Fl,usa
I have seen a lot of the teflon jacket splitting off but the thermoplastic insulation always seems OK.


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#185814 - 03/29/09 05:19 PM Re: Brittle THHN insulation on NM-B conductors [Re: gfretwell]  
newsgraphics  Offline
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Joined: Nov 2005
Posts: 11
California
Must have been Chinese made wire or something!


#185817 - 03/29/09 09:14 PM Re: Brittle THHN insulation on NM-B conductors [Re: newsgraphics]  
KJay  Offline
Member
Joined: Nov 2007
Posts: 763
MA, USA
Just wondering, did you remove the NM outer jacket with a utility razor knife or maybe use those Klein NM cable stripping pliers?
I've often seen the type of problem you described when these tools are used.


#185820 - 03/30/09 02:15 AM Re: Brittle THHN insulation on NM-B conductors [Re: KJay]  
newsgraphics  Offline
Member
Joined: Nov 2005
Posts: 11
California
Hard to say what kind of tool was used by the original installers, this is a tract home, but your suspicions sound quite plausible.



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