ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
New fan motor for Panasonic
by HotLine1. 06/25/19 03:53 PM
Burning out of return(white) side of 120volt rec
by crselectric. 06/14/19 02:15 AM
Video door bell causing chime activation of coil
by JoeTestingEngr. 06/13/19 12:43 PM
Troubleshooting Voltage Drop Across Relay
by gfretwell. 06/09/19 11:49 AM
Apple Recalls Three-Prong Wall Plug Adapters
by Admin. 06/05/19 09:06 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 13 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Fiberglass insulation #50563
04/06/05 12:38 AM
04/06/05 12:38 AM
P
PEdoubleNIZZLE  Offline OP
Member
Joined: Jun 2004
Posts: 176
McKeesport, PA, USA
I want to know what the proper way is to install fiberglass insulation around 1) Wires running along/thru studs, 2) Around Outlet Boxes, and 3) Around Light fixtures, where it will be hot. (All NM-B, no conduits or ac). (I know that nobody is liable for any advice blah blah blah legal stuff here blah blah blah)

Work Gear for Electricians and the Trades
Re: Fiberglass insulation #50564
04/06/05 07:39 PM
04/06/05 07:39 PM
E
Electricmanscott  Offline
Member
Joined: Jan 2002
Posts: 1,457
Holden, MA USA
You might want to ask that in the insulation forum. [Linked Image]

Re: Fiberglass insulation #50565
04/06/05 09:12 PM
04/06/05 09:12 PM
H
HLCbuild  Offline
Member
Joined: Dec 2004
Posts: 209
Herndon,Va USA
In VA. our inspectors require us to remove the paper backing within 6" of a recessed type IC fixture. The fiberglass batt can be snug to the fixture. There doesn't seem to be any other problems around boxes or NM-B. We do tuck it behind the box to satisfy the energy code and help prevent drafts thru the outlets.

Re: Fiberglass insulation #50566
04/06/05 09:29 PM
04/06/05 09:29 PM
H
hbiss  Offline
Member
Joined: Dec 2003
Posts: 886
Hawthorne, NY USA
The important thing with fiberglass insulation is that you don't want to compress it. If you do the R value will be less where it is compressed.

With that in mind a good insulation installer will do a knife cut partially through the batt from the backside to put a horizontal cable in the center of the insulation without compressing it. The same can be done for vertical runs only the insulation can be split with your fingers to accommodate the cable.

I like to see the space behind a box (between the back of the box and the sheathing) filled with uncompressed insulation. You again would split the insulation with your fingers, slide a layer behind the box then cut the front layer away around the box. I think that the thin uncompressed layer behind the box has a higher R value than the whole thickness shoved in there.

Light fixtures in insulation should be type IC so they can (and should) be completely covered following the same rules I gave above if applicable.

-Hal


Featured:

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

 

Member Spotlight
sbi
sbi
indiana
Posts: 47
Joined: March 2008
Show All Member Profiles 
Top Posters(30 Days)
Admin 2
Khombo 2
Popular Topics(Views)
255,884 Are you busy
191,858 Re: Forum
181,623 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.016s Queries: 14 (0.004s) Memory: 0.9600 MB (Peak: 1.0919 MB) Zlib enabled. Server Time: 2019-06-26 22:46:50 UTC