ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Positive Ground on 125 VDC Station Batteries
by The Watt Doctor. 05/23/19 08:55 AM
2020 is at the printers.
by gfretwell. 05/22/19 10:11 AM
Chinese wire symbols?
by Texas_Ranger. 05/19/19 03:09 PM
Pool - Daisy chained GFCI
by gfretwell. 05/18/19 01:30 PM
110.26 working clearances
by HotLine1. 05/14/19 02:08 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 13 guests, and 20 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
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: 12
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?

2017 / 2014 NEC & Related Books and Study Guides
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: 9,362
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: 12
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: 12
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.


Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Tom
Tom
Shinnston, WV USA
Posts: 1,044
Joined: January 2001
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
255,214 Are you busy
191,280 Re: Forum
181,048 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.019s Queries: 15 (0.004s) Memory: 0.9682 MB (Peak: 1.1081 MB) Zlib enabled. Server Time: 2019-05-25 19:15:15 UTC