Expandable Foam as Duct Seal

[LarryFine]

I know, but to me this is fairly ridiculous considering that the insulation contractors will use expanding form around all NM cables in a home due to building code requirements.

When I need to add a wire, if I see foam, I don't even try to break it out. I just sigh and drill a new hole.

 

[iwire]

When I need to add a wire, if I see foam, I don't even try to break it out. I just sigh and drill a new hole.

I don't blame you.

Quick 'foam story.

I was in a basement of 25,000 sq ft home working on the service with a power company meter guy, there was a 4" conduit being used for the CT metering conductors and it was sealed closed with foam. I start chipping the foam out and almost right away it makes a noise like a leaking tire, I look at the POCO guy and say 'Not good' he understands and quickly dumps a trash barrel and hands it to me a bit late, the water was now coming on strong, I would say 10 to 15 gals by the time it stopped, I was soaked, the 1200 amp MCB was soaked, floor soaked. Just one of those great days and the boss still sent me to another call after that, I smelled like swamp water. :grin:

 

[electricalperson]

i never see people seal raceways that go from outside to inside. whenever i do they yell at me:grin:

 

[ohm]

UL listed Duct Seal
http://www.rectorseal.com/files/207/dsductseal.pdf

I'll bet half a doz. bricks of that stuff in you carry-on luggage would get a little attention at the airport.:grin:

 

[petersonra]

I actually called one of the foam manufacturers once and asked them. They said they had done testing of the foam and found it did not degrade conductor insulation.

Ironically, they did say it should not touch bare wires.

 

[SPARKS40]

Quick question about your average everday foam sealant (e.g. Great Stuff). This product is advertised for sealing around pipes, wires, etc., but it is combustible both when uncured AND cured. So, my question is, how could this product, or any product of this type be acceptable in regard to structural fire ratings? FYI, the only product i use for sealing gaps, cracks, etc., as they apply to electrical installs is an approved fire rated caulking compound.

 

[charlietuna]

We had a remodel on a medical testing lab that had twelve individual buildings with underground raceways between them. Duct banks of power and seperate data systems were installed between the buildings. There was one remodel about eight years ago. The original raceways were sealed with duct seal. The remodel was sealed with expandable foam. Our contract required some repulls on both the original and remodeled raceways. Don't know what the foam product was, but after a few days we quickly realized we were wasting our time on any thought of removing it! We ended up getting an extra and abandoning the foamed raceways and re-pulling the original duct sealed raceways to meet the requirements of our remodel. The original building's engineer was used on all projects. He was quick to notify us on what product to seal the raceways, it wasn't rector seal, but it came in five gallon buckets and it was U.L. rated.

 

[ohm]

Quick question about your average everday foam sealant (e.g. Great Stuff). This product is advertised for sealing around pipes, wires, etc., but it is combustible both when uncured AND cured. So, my question is, how could this product, or any product of this type be acceptable in regard to structural fire ratings? FYI, the only product i use for sealing gaps, cracks, etc., as they apply to electrical installs is an approved fire rated caulking compound.

I often wondered along the same lines about the big orange & blue stores etc. placing combustible stickers on the inside of boxes w/ the SKU #'s.

 

[electricmanscott]

Quick question about your average everday foam sealant (e.g. Great Stuff). This product is advertised for sealing around pipes, wires, etc., but it is combustible both when uncured AND cured. So, my question is, how could this product, or any product of this type be acceptable in regard to structural fire ratings? FYI, the only product i use for sealing gaps, cracks, etc., as they apply to electrical installs is an approved fire rated caulking compound.

That is a valid question and I think the answer is isn't acceptable. To be clear I don't think that is what this thread is about. I think it was more a question of general sealing rather than firestopping. I could be wrong though.

 

[charlietuna]

It is fine to use mixed stucco concrete to patch holes around boxes and pipes in concrete walls---but you wouldn't want to use it to seal space around conductors in a raceway! There are reasons to seal these pipes, but also reasons to use the proper product which allows future replacement of the conductors. The use of any product that prevents the removal of the conductors reduces the design use of the raceway.