Conduit Foam Sealant (Raceways, Combiner Panels, Inverters)

[rakish66]

A discussion recently came up as to what requirements, if any, are there for the types of sealant allowable for conduits per the NEC.

I've come across some sites that have expandable foam (like GreatStuff) in AC Combiner Panels, Sub Panels, Inverters, etc.
Is there any code violation or other issues that could arise for using the foam in these applications?

NEC 300.7(A) only dictates the requirement to prevent the circulation of air and doesn't specify types of sealants.

It seems there is only a temperature requirement. Is there also a flammability requirement?

 

[petersonra]

A discussion recently came up as to what requirements, if any, are there for the types of sealant allowable for conduits per the NEC.

I've come across some sites that have expandable foam (like GreatStuff) in AC Combiner Panels, Sub Panels, Inverters, etc.
Is there any code violation or other issues that could arise for using the foam in these applications?

NEC 300.7(A) only dictates the requirement to prevent the circulation of air and doesn't specify types of sealants.

It seems there is only a temperature requirement. Is there also a flammability requirement?

It seems to me it is a good option. Unfortunately it is not listed for use inside of conduit, so some people claim it is inappropriate.

 

[texie]

American Polywater makes various products just for this purpose.

 

[don_resqcapt19]

The 2020 code added the following language to that section.

Sealants shall be identified for use with cable insulation, conductor insulation, a bare conductor, a shield, or other components.

 

[tom baker]

The American polywater works great and can be removed. The great stuff is a poor choice, not identified and be difficult to remove. Monkey poo is a viable option

 

[roger]

I once asked DuPont for a letter supporting using Great Stuff around conductors inside conduit, they would not oblige saying to ask the inspector. I told the tech support people I would not be asking if the inspector had not requested it. I quit using Great Stuff pretty much for everything after that.

 

[tom baker]

It seems to me it is a good option. Unfortunately it is not listed for use inside of conduit, so some people claim it is inappropriate.

When there is an approved product Poywater, that I have used, no need to use great stuff

 

[garbo]

I started using bathroom silicone caulk to seal wires running into walk in refrigerated units.& freezers starting in early 1970's but never gave it much thought. Went back years later and replaced old wires with type TW insulation and both the silicone and insulation were in great shape. Saw some guys use ducseal that in the time always cracks and appear to then let air flow thru causing condensation. Now retired but would only use a labeled product today.

 

[winnie]

The American polywater works great and can be removed. The great stuff is a poor choice, not identified and be difficult to remove. Monkey poo is a viable option

In your experience how easy is it to remove the polywater foam? I have no experience with it.

Thanks
Jon