Go Back   InterNACHI Inspection Forum > >

Notices

Electrical Inspections Contains discussions about electrical systems. This includes receptacles, panels, wiring, etc.

Reply
 
Thread Tools
  #1  
Old 11/3/15, 10:57 AM
Andrew A. Griffin, CMI's Avatar
Andrew A. Griffin, CMI Andrew A. Griffin, CMI is offline
Certified Professional Inspector (CPI)
 
Join Date: Aug 2012
Location: Pittsburgh, PA.
Posts: 412
Default Spray foam over romex

This is not for a client, I am just trying to get better educated:

I do not see a lot of spray foam, in the walls, in new construction around here; so I have never thought about this before. The insulator spray foamed (closed cell) all of the roughed in romex. The city inspector was giving the electrician a hard time about it, but passed it. I guess the inspector was concerned about heat buildup because of the foam encasing the wiring, which is why he was giving the electrician a hard time.

Would there be significant heat buildup? Is there anything in the current code cycle that would prevent spray foam over romex? Has anyone heard of any issues because of this?
Attached Thumbnails
Spray foam over romex-pb030653-w1024-h768-jpg   Spray foam over romex-pb030652-w1024-h768-jpg  




Andy Griffin
Griffin Inspection Services LLC
agriffin@griffinspection.com
412-407-2501
www.griffinspection.com
www.pittsburgh-home-inspections.com
Pittsburgh home inspections
Reply With Quote
Need a home inspection in Utah? Check out InterNACHI's listing of Utah certified home inspectors. Or, find a home inspector anywhere in the world with our inspection search engine.
  #2  
Old 11/3/15, 12:54 PM
Justin Shields's Avatar
Justin Shields Justin Shields is offline
InterNACHI Member
 
Join Date: Sep 2012
Location: Minneapolis,MN
Posts: 113
Default Re: Spray foam over romex

Happens all the time since the insulation comes in after the trades (HVAC, plumbing, electrical) rough in. Highly doubt it will be an issue. Not sure though if NEC addresses this issue....it may?.... Ya could go around the house and break it all off the romex. No Fun!
Reply With Quote
  #3  
Old 11/3/15, 1:09 PM
Robert Meier's Avatar
Robert Meier Robert Meier is online now
Active Poster
 
Join Date: Feb 2010
Location: New Jersey
Posts: 3,256
Please Note: Robert Meier is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: Spray foam over romex

The NEC doesn't directly address spray foam insulation. If the cables are separated within the insulation there is no code issue.
Reply With Quote
  #4  
Old 11/3/15, 1:46 PM
Rick Elliott's Avatar
Rick Elliott Rick Elliott is offline
Certified Professional Inspector (CPI)
 
Join Date: May 2012
Location: Marin County, California
Posts: 1,469
Default Spray foam over romex

I would say encasing any junctions or boxes would be the issue and not the romex per say.
Reply With Quote
  #5  
Old 11/9/15, 12:09 PM
Paul W. Abernathy's Avatar
Paul W. Abernathy Paul W. Abernathy is offline
Certified Master Inspector ®
 
Join Date: Sep 2005
Location: McKinney, TX
Posts: 9,784
Send a message via Skype™ to pabernathy
Default Re: Spray foam over romex

The correct term would be Nonmetallic-Sheathed Cable (Type MN-B) and the NEC does address the issue of how you would have to adjust for the "in contact" aspect of the ampacity variance.

From a manufacturers perspective, the manufacturer of the "Foam" would need to make a statement regarding it's testing for use with Type NM-B Cable. The heat generated during the curing process is documented. However, most of the makers of the foam have done the testings needed to determine that it does not cause any negative effects on the PVC sheathing, but they need to document this in their specifications.

Wire and Cable Manufacturers do not do these testings normally due to a wide variety of manufactures of the "foam" open and closed cell products. So when asked we usually tell them to consult with the foam manufacturer because we sell our products to be installed in buildings, they produce foam to encase our wires so they have the responsibility to provide the tests and documentation.



Paul W. Abernathy, CMECP®
NFPA 70 (NEC®) Code Panel Member on #5 and #17
Founder of the Certified Master Electrical Code Professional® Program
CMECP® Website - www.MyCMECP.com
Website - http://www.masterthenec.com
Twitter - https://twitter.com/MasterTheNEC
Facebook -https://www.facebook.com/masterthenec/
Spreaker PodCasts - https://www.spreaker.com/show/master-the-necs-tracks


Disclaimer - All my posts on this forum represent Electrical Code Academy, Inc.
Reply With Quote
  #6  
Old 11/9/15, 1:40 PM
Bob Elliott, 450.0002662's Avatar
Bob Elliott, 450.0002662 Bob Elliott, 450.0002662 is offline
Certified Professional Inspector (CPI) ®
 
Join Date: Aug 2006
Location: Chicago
Posts: 37,704
Default Re: Spray foam over romex

Paul if double insulating conductors is not allowed common sense tells me closed cell foam surrounding non metallic conductors is even worse. Under what law of physics can a this be a acceptable situation or is running Romex through conduit cool now?
Reply With Quote
  #7  
Old 11/9/15, 2:03 PM
Jim Port Jim Port is online now
Unmoderated Guest
 
Join Date: Jul 2007
Location: Maryland
Posts: 2,642
Please Note: Jim Port is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: Spray foam over romex

There is no prohibition against NM in conduit. It is specifically required in some instances for protection against physical damage.
Reply With Quote
  #8  
Old 11/10/15, 11:24 AM
Erik Schmidt Erik Schmidt is online now
Certified Professional Inspector (CPI)
 
Join Date: Nov 2012
Location: Edmonton Alberta
Posts: 2,377
Default Re: Spray foam over romex

NM plastic wire has a maximum temperature rating, usually 90 C. Wires heat up when current passes through them. Sheathed wire is supposed to be installed surrounded by air, such as between studs or joists, so that heat build up can dissipate. When surrounded by insulation heat can't dissipate. Hotter wires also have higher resistance, so heat that can't dissipate generates more heat. In other words the conditions for the perfect (fire) storm. The better the insulation the greater the danger.



Erik Schmidt


East Side Home Inspection
Edmonton Alberta
780 477 2666
Reply With Quote
  #9  
Old 11/10/15, 1:02 PM
Robert Meier's Avatar
Robert Meier Robert Meier is online now
Active Poster
 
Join Date: Feb 2010
Location: New Jersey
Posts: 3,256
Please Note: Robert Meier is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: Spray foam over romex

Quote:
Originally Posted by eschmidt View Post
NM plastic wire has a maximum temperature rating, usually 90 C. Wires heat up when current passes through them. Sheathed wire is supposed to be installed surrounded by air, such as between studs or joists, so that heat build up can dissipate. When surrounded by insulation heat can't dissipate. Hotter wires also have higher resistance, so heat that can't dissipate generates more heat. In other words the conditions for the perfect (fire) storm. The better the insulation the greater the danger.
There is no danger of NM cable overheating when being installed within insulating material if done so according to the NEC.

Last edited by Robert Meier; 11/10/15 at 1:10 PM..
Reply With Quote
  #10  
Old 11/10/15, 1:09 PM
Christopher Currins, CMI Christopher Currins, CMI is offline
Certified Master Inspector ®
 
Join Date: Feb 2007
Location: Godfrey, IL
Posts: 17,623
Default Re: Spray foam over romex

Quote:
Originally Posted by eschmidt View Post
NM plastic wire has a maximum temperature rating, usually 90 C. Wires heat up when current passes through them. Sheathed wire is supposed to be installed surrounded by air, such as between studs or joists, so that heat build up can dissipate.
Any modern home (built in the last 40 years) will have some type of Insulation packed between studs and joist at all exterior walls, and attic floors.
Reply With Quote
  #11  
Old 11/10/15, 4:07 PM
Paul W. Abernathy's Avatar
Paul W. Abernathy Paul W. Abernathy is offline
Certified Master Inspector ®
 
Join Date: Sep 2005
Location: McKinney, TX
Posts: 9,784
Send a message via Skype™ to pabernathy
Default Re: Spray foam over romex

Quote:
Originally Posted by belliott View Post
Paul if double insulating conductors is not allowed common sense tells me closed cell foam surrounding non metallic conductors is even worse. Under what law of physics can a this be a acceptable situation or is running Romex through conduit cool now?
Sorry...Not sure I understand the question. And if you are inferring that sheathing counts as "insulation" then you are a bit off my friend.

The Type NM Cable in a raceway is not really the problem, it is how you would secure it to the enclosure or device box that becomes the problem except of course specific aspects of the NEC like 312.5(C) Exception or 314.17(C) Exception. However, in any case it is also very common to install Type NM-B Cable in short raceways for protection or even as detailed in 334.10(5) where applicable.

The point is...we have adjustments and corrections for a reason. They are limitations that serve to prevent damage to the conductors insulation and thus causing a potential circuit failure..or worse!

The sheathing is generally rated the same (at least ours is) as the conductor insulation but simply as a issue of product material and is kinda irrelevant to the question. The foam producing manufacturers are the individuals who have to say placing their foam in contact with our nonmetallic-sheathing and subsequent conductors is ok...not the Wire and Cable industry.

FYI- Here is a great article by Charlie Trout http://www.ecmag.com/section/codes-s...cable-and-more



Paul W. Abernathy, CMECP®
NFPA 70 (NEC®) Code Panel Member on #5 and #17
Founder of the Certified Master Electrical Code Professional® Program
CMECP® Website - www.MyCMECP.com
Website - http://www.masterthenec.com
Twitter - https://twitter.com/MasterTheNEC
Facebook -https://www.facebook.com/masterthenec/
Spreaker PodCasts - https://www.spreaker.com/show/master-the-necs-tracks


Disclaimer - All my posts on this forum represent Electrical Code Academy, Inc.

Last edited by pabernathy; 11/10/15 at 4:10 PM.. Reason: Added Article-Enjoy!
Reply With Quote
  #12  
Old 11/10/15, 5:12 PM
Bob Elliott, 450.0002662's Avatar
Bob Elliott, 450.0002662 Bob Elliott, 450.0002662 is offline
Certified Professional Inspector (CPI) ®
 
Join Date: Aug 2006
Location: Chicago
Posts: 37,704
Default Re: Spray foam over romex

Paul I have heard you are not allowed to double insulate or run Non Metallic through conduit do to heat build up for ages.

Go take a look at the many discussions around the internet on it.

Blows my mind it is OK.

Around here Non metallic is not allowed so is it OK to use Romex through conduit then ? hmmmm.

Last edited by belliott; 11/10/15 at 5:31 PM..
Reply With Quote
  #13  
Old 11/10/15, 6:29 PM
Jim Port Jim Port is online now
Unmoderated Guest
 
Join Date: Jul 2007
Location: Maryland
Posts: 2,642
Please Note: Jim Port is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: Spray foam over romex

The NEC does not prohibit NM through conduit. Consider your mind blown. As I said above, the code specifically calls for conduit to protect NM against physical damage.
Reply With Quote
Need a home inspection in Utah? Check out InterNACHI's listing of Utah certified home inspectors. Or, find a home inspector anywhere in the world with our inspection search engine.
  #14  
Old 11/10/15, 7:11 PM
Bob Elliott, 450.0002662's Avatar
Bob Elliott, 450.0002662 Bob Elliott, 450.0002662 is offline
Certified Professional Inspector (CPI) ®
 
Join Date: Aug 2006
Location: Chicago
Posts: 37,704
Default Re: Spray foam over romex

So since we are not pencil neck geek code inspectors lets talk in the real world.
When is overheating from surrounding environment a factor.
Lets take over packing junction boxes and while we are at it how about running my Christmas light extension cord through conduit.
Maybe go further and discuss extension cords running through walls.

Past code what is the difference and is it all Ok or not ?

Was I wrong ?

Last edited by belliott; 11/10/15 at 7:16 PM..
Reply With Quote
  #15  
Old 11/10/15, 7:22 PM
Robert Meier's Avatar
Robert Meier Robert Meier is online now
Active Poster
 
Join Date: Feb 2010
Location: New Jersey
Posts: 3,256
Please Note: Robert Meier is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: Spray foam over romex

Bob,

Do you think that an NM cable embedded in insulation and properly protected by an OCPD is really a problem?
Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -4. The time now is 11:54 PM.
no new posts