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Brittle THHN insulation on NM-B conductors #185812
03/29/09 05:44 PM
03/29/09 05:44 PM
N
newsgraphics  Offline OP
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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Re: Brittle THHN insulation on NM-B conductors [Re: newsgraphics] #185813
03/29/09 06:17 PM
03/29/09 06:17 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,242
Estero,Fl,usa
I have seen a lot of the teflon jacket splitting off but the thermoplastic insulation always seems OK.


Greg Fretwell
Re: Brittle THHN insulation on NM-B conductors [Re: gfretwell] #185814
03/29/09 06:19 PM
03/29/09 06:19 PM
N
newsgraphics  Offline OP
Member
Joined: Nov 2005
Posts: 11
California
Must have been Chinese made wire or something!

Re: Brittle THHN insulation on NM-B conductors [Re: newsgraphics] #185817
03/29/09 10:14 PM
03/29/09 10:14 PM
K
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.

Re: Brittle THHN insulation on NM-B conductors [Re: KJay] #185820
03/30/09 03:15 AM
03/30/09 03:15 AM
N
newsgraphics  Offline OP
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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