ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Recent Posts
VFD MotorFeeders
by gfretwell. 10/19/17 01:02 AM
Generator Cable Sizing
by brsele. 10/18/17 07:39 PM
What do you do?
by gfretwell. 10/17/17 01:08 AM
Good ol' copper pipe in the fuse holder trick
by HotLine1. 10/16/17 07:16 PM
Another generator question
by HotLine1. 10/16/17 07:02 PM
New in the Gallery:
Gallery Test
Popular Topics(Views)
241,387 Are you busy
177,342 Re: Forum
168,954 Need opinion
Who's Online Now
0 registered members (), 34 guests, and 12 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
Page 1 of 4 1 2 3 4
#216752 - 02/11/16 07:55 PM NMC in contact with spray foam insulation?  
sparkync  Offline
Member
Joined: Oct 2002
Posts: 828
NC
Anyone heard the the affect that spray foam has on romex?
Have a customer that had her whole walk in attic sprayed full of it. Romex cable, etc...

Thanks...


Work Gear for Electricians and the Trades

#216754 - 02/11/16 09:39 PM Re: NMC in contact with spray foam insulation? [Re: sparkync]  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
NEMA issues a "white paper" some time ago on the topic. The short version? No need to change anything .... the foam will not harm the cable, and derating remains the same.


#216756 - 02/11/16 10:21 PM Re: NMC in contact with spray foam insulation? [Re: sparkync]  
sparkync  Offline
Member
Joined: Oct 2002
Posts: 828
NC
Ok. Thanks for info..


#216758 - 02/12/16 02:18 AM Re: NMC in contact with spray foam insulation? [Re: sparkync]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,123
Estero,Fl,usa
The only time it becomes an issue is if a couple cables are bundled in the foam or going through a penetration sealed with foam. You treat it like a raceway at that point. (you derate)
334.80


Greg Fretwell

#216760 - 02/12/16 08:24 AM Re: NMC in contact with spray foam insulation? [Re: sparkync]  
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,402
Vienna, Austria
I've seen PVC react with foam but AFAIK it affects the foam rather than the PVC. The end result is that both stick together. Probably plasticisers from the PVC soften the foam and make it sticky. That's why you should never store vintage equipment in its original box without separating any cords from the foam. Now that I think of it the RF cable of the Commodore C-16 I sold some time ago did have melted spots from the packaging!


#216762 - 02/14/16 03:09 AM Re: NMC in contact with spray foam insulation? [Re: sparkync]  
dougwells  Offline


Member
Joined: May 2003
Posts: 1,140
kamloops BC Canada
Apparently Canada had a bad run with spray foam and romex about 10 years ago.. it was destroying the jacket on the romex.

http://safetyauthority.ca/sites/def...%20Polyurethane%20Spray%20Form%20Ins.pdf

Last edited by dougwells; 02/14/16 03:45 AM. Reason: to add link

#216763 - 02/14/16 01:47 PM Re: NMC in contact with spray foam insulation? [Re: sparkync]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,872
Brick, NJ USA
There were some issues with foam related to the chemical contained in the product that I recall from time past.

NM jacket becoming soft and 'melting', similar to what happens with a non-latex base primer used in fire restoration jobs.

Time to check out Dougs link


John

#216774 - 02/17/16 01:25 AM Re: NMC in contact with spray foam insulation? [Re: gfretwell]  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Originally Posted by gfretwell
The only time it becomes an issue is if a couple cables are bundled in the foam or going through a penetration sealed with foam. You treat it like a raceway at that point. (you derate)
334.80


Yes but i am confused Greg....

334.80 forbids 310.15 A 2 EX. & requires 310.15 B 3>>>

Quote
Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(3)(a).


338.80 in part reads>
Quote
Where more than two NM cables containing two or
more current-carrying conductors are installed, without
maintaining spacing between the cables, through the same
opening in wood framing that is to be sealed with thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 31 0.15(B)(3)(a) and the provisions of 310.15(A)(2), Exception, shall not apply.


Most of our installs are required to have fire caulk between floors and/or units. These holes might be 4-5" in length, not 24" , so can i take it the 24" is relevant here?

I ask , because local code 'lore' seems to think otherwise, or perhaps said firecaulk does not work well for mutli-wires?


~S~

Last edited by sparky; 02/17/16 01:26 AM.

#216775 - 02/17/16 01:29 AM Re: NMC in contact with spray foam insulation? [Re: dougwells]  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Originally Posted by dougwells
Apparently Canada had a bad run with spray foam and romex about 10 years ago.. it was destroying the jacket on the romex.

http://safetyauthority.ca/sites/def...%20Polyurethane%20Spray%20Form%20Ins.pdf


But they are talking about mechanical strain, not thermal damage

~S~


#216777 - 02/17/16 03:00 AM Re: NMC in contact with spray foam insulation? [Re: sparkync]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,123
Estero,Fl,usa
Sparky, I agree the fairly new 334.80 does not really make a lot of sense.
The NEMA, study often cited, even makes it more confusing since it really just refers to the foam not damaging the jacket. I see nothing that indicates short sections in foam would overheat.

http://gfretwell.com/electrical/NEMA%20Romex%20in%20foam%20study.pdf

But rulz is rulz.


Greg Fretwell

Page 1 of 4 1 2 3 4

Member Spotlight
Attic Rat
Attic Rat
Bergen Co.,N.J. USA
Posts: 524
Joined: December 2003
Show All Member Profiles 
Featured:

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

 

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.026s Queries: 16 (0.005s) Memory: 0.8240 MB (Peak: 1.0073 MB) Zlib enabled. Server Time: 2017-10-19 07:24:32 UTC