Spray foaming load center in exterior wall

N

nizak

Senior Member
Had a General Contractor just call and ask if it’s allowable to spray foam a load center that’s installed in a wall separating a finished garage and residential living space.

I don’t know the physical properties of the product, but he said it would be applied about 1 1/2” thick on the back side and also encapsulate all the NM cable the same going into the load center.

My thought was that any penetration of the product into the load center would cause a code concern.

Probably not much help with heat dissipation either.

Thanks
 
R

rc/retired

Senior Member
Location
Bellvue, Colorado
Occupation
Master Electrician/Inspector retired
I don't see a problem. It has been done in my city quite often to achieve maximum R-value.
Tape the holes on the back if you're concerned.

Ron
 
W

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
dkidd said:
If that is a fire wall, the panel should not be in it.
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For a detached single family residence, the wall between an attached garage and habitable space is not a "fire wall". It does have specific separation requirements per IRC R302.6, which are "Not less than 1/2-inch gypsum board or equivalent applied to the garage side." Installing a panelboard enclosure between the studs that faces the habitable space, not the garage, would not interfere with that.

Of course, the OP is a little light on information, like which way the panelboard faces and whether this is a detached single family residence.

Cheers, Wayne
 
W

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
rc/retired said:
In my town the panels faced the garage.
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Right, so I'm a bit unclear on what exactly R302.6 has to say about that configuration. The penetration of the R302.6 1/2" drywall separation would be similar to putting a receptacle box in that wall facing the garage, just a much larger area. But I don't find any language that differentiates between the two cases.

R302.6 says "Openings in garage walls shall comply with Section R302.5." Then R320.5.3 "Other penetrations" says "Penetrations through the separation required in Section R302.6 shall be protected as required by Section R302.11, Item 4."

R302.11 is fireblocking, and item 4 just says "At openings around vents, pipes, ducts, cables and wires at ceiling and floor level, with an approved material to resist the free passage of flame and products of combustion. The material filling this annular space shall not be required to meet the ASTM E136 requirements." So that makes it sounds like all you would need to do is appropriately seal between the drywall and the panelboard enclosure, as well as every entry to the panelboard enclosure.

Yet I've heard of the idea that instead you have to effectively create a drywalled niche and set the panelboard in the niche, and then approriately seal every drywall penetration of the niche. I don't see how the citation chain above supports that requirement.

Cheers, Wayne
 
N

nizak

Senior Member
wwhitney said:
For a detached single family residence, the wall between an attached garage and habitable space is not a "fire wall". It does have specific separation requirements per IRC R302.6, which are "Not less than 1/2-inch gypsum board or equivalent applied to the garage side." Installing a panelboard enclosure between the studs that faces the habitable space, not the garage, would not interfere with that.

Of course, the OP is a little light on information, like which way the panelboard faces and whether this is a detached single family residence.

Cheers, Wayne
Click to expand...
It is an attached garage and the panel faces into the garage.

Both rough electrical and building inspections have been approved.

Garage side will have 5/8” drywall, interior wall will have 1/2”. Don’t know if the 5/8” drywall carries a specific X designation or if all 5/8 just does.

I would think that if there was an issue with the panel face orientation it would have been flagged at the rough in inspection.

Unable to face it into the dwelling since there’s a closet there.
 
W

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
wwhitney said:
Yet I've heard of the idea that instead you have to effectively create a drywalled niche and set the panelboard in the niche, and then appropriately seal every drywall penetration of the niche. I don't see how the citation chain above supports that requirement.
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I found this formal interpretation from the ICC for the 2015 IRC:


Assuming it is still valid, the ICC says there's no need to do the above "niche". All you'd have to do is seal between the panelboard enclosure and gypsum board (and maybe the openings in the panelboard enclosure?) as per R302.11 Item 4.

Cheers, Wayne
 
J

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
nizak said:
Had a General Contractor just call and ask if it’s allowable to spray foam a load center that’s installed in a wall separating a finished garage and residential living space
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Is this a fire proofing/smoke foam or is it for thermal insulation purposes?
Load centers are regularly installed in insulated walls.

As other have said, a good design would include a means of future entry to the panel.
 
Buck Parrish

Buck Parrish

Senior Member
Location
NC & IN
I put drywall behind mind and surface mounted it to it. All the wires to. I'll try to find a pic. I done this because during a fire all the flames were coming through the panel. As I recall there was a washer machine box that melted allowing a draft.
 
roger

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
I apologize for getting off track, to the OP's question, there is nothing prohibiting it as far as the NEC is concerned.
 
B

BarryO

Senior Member
Location
Bend, OR
Occupation
Electrical engineer (retired)
nizak said:
Probably not much help with heat dissipation either.
Click to expand...
Aren't NM cables in exterior walls routinely placed within insulation? With 90 degree conductors rated at 60 degree ampacity, it shouldn't be a problem.
 
D

David Castor

Senior Member
Location
Washington, USA
Occupation
Electrical Engineer
I would read the spray foam instructions and warning very carefully. Some of these compounds can attack certain types of plastics. Not sure about the NM jacketing.
 
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