foam insul

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donselectric

Senior Member
Location
nh
hi all,
has anyone had experience with the srayon foam insul ?
i'm doing a reno and they are using it. how does it do with rx ?
i dont know what product it is but it creates heat for shure...


thanks
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
You talking about this stuff?

ry%3D400
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
donselectric said:
i planned on wiring before they shot it, didn't know what the curing process would do to insulation...
Click to expand...

I would try and separate my cables as much as possible in those areas. Also if they do the ceilings I would be cautious if they blow on top of the cans. If they do that, and they did on one of my jobs, you cannot get access to the can jb anymore-- a violation.
 
chris kennedy

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
donselectric said:
i planned on wiring before they shot it, didn't know what the curing process would do to insulation...
Click to expand...

There was a link posted here with a warning from Canada on the effects of this product on the outer sheath of NM. Any of you resi guys remember that?
 
electricmanscott

electricmanscott

Senior Member
Location
Boston, MA
Long story short...


In summary:
The National Electrical Code? does not prohibit installing Type NM-B cable in spray foam
insulation.
The NEC? contains requirements for derating the conductors when bundled together. These, and
all other Code requirements, must be followed.
The manufacturers of Type NM-B cable allow encasing the cable in foam insulation.
The University of Toronto study indicates that the conductors will not be subjected to
objectionable temperatures even under very severe conditions.
Type NM-B cable is routinely installed within heavily insulated walls, ceilings, and floors with
no reported detrimental effects
 
D

donselectric

Senior Member
Location
nh
nowhere do i see a concern about the heat generated when the two chems are combined. so i take it there isn't any... is that safe to say ? should i not wire before spraying?.....:-?
 
D

donselectric

Senior Member
Location
nh
ya i know but it looked like the pic here that rx was pretty clean...i figured it was put in after...like i said my intent was to do it before but i dont want to find out after that insulation melted...the only time i ran into this it was comm and everything was emt...
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
donselectric said:
ya i know but it looked like the pic here that rx was pretty clean...i figured it was put in after...like i said my intent was to do it before but i dont want to find out after that insulation melted...the only time i ran into this it was comm and everything was emt...
Click to expand...

I have done a few foam jobs and have not had an issue with the nm in the foam. The picture I posted showed a nm cable that was installed after the foam because the HO added something. Everything else is embedded in the foam. I hate the stuff.
 
E

eds

Senior Member
I hate the stuff, a few thingss to think about, vanity fixture boxes should be set at rough in sometimes they spray that stuff as sound proofing. I box out all recess cans for two reasons, acces to j-box and some manufactures require a 10 - 15% wattage reduction when encapsulated in foam. One type of foam they come back with chainsaws and trim flush with studs so watch wires stubbed out. Open cell foam is fishable, closed cell foam is a major pain. I like to leave a small loop in the attic when using a pan box (due to my friend the router) bad idea when they foam the attic. One nice thing is when they foam the bottom of the roof sheating the attic space is only about 5 to 10 degrees warmer then the living space
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
donselectric said:
thanks...thats what i was curious about...now who tapes out the boxes ?
prob should be me i quess...

thanks again.
Click to expand...

I never taped the boxes. Around here they only put about 2 to 2.5" in the walls and they don't appear to get it in the box. So either they taped the box or they are a good aim with the stuff. :smile:
 
TwinCitySparky

TwinCitySparky

Senior Member
Location
Minnesota
Use care with the "closed cell" foam. During the cure it gets pretty warm. It has a higher R value so is used primarily on outside walls. I wired a house two years ago and called the foam rep who tried to assure me that NM will be OK in the closed cell during the curing process.

Low voltage - telephone, doorbell, stat is another story. I've seen it happen. Smurf tube em where they touch the stuff.
 
H

hillbilly

Senior Member
I was curious about this exact situation a few years ago, before I had any access to the specifics.

I cut a 2 foot length of NMB and buried it in "Great Stuff" foam and left it about a year.

When I cut the foam away, the NM looked as good as new.

Not very scientific, but it eased my mind about NM and spray foam.:smile:

steve
 
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