Sealing raceways into a residential building

S

Sparro

Member
Location
Colorado
Occupation
Master Electrician
Hi all,

I’m looking for the best product to seal the penetration from my main panel into a single- or multi-family home. Lately, inspectors in my area have become more aggressive about ensuring that materials are used strictly for their listed purposes, so I want to be sure I’m using something appropriate and defensible.

I’ve seen quite a few electricians use expanding foam to seal between thermally variable environments, but I’ve never been a big fan of that approach, mostly because I suspect foam tends to hold moisture over time. I prefer to use duct seal, but I haven’t been able to find any that are specifically listed for electrical use. Companies like Ideal, Gardner Bender, and others make duct seal marketed for the trade, but none of them explicitly say it’s suitable for electrical installations.... they also don’t say it isn’t.

I might be making a mountain out of a molehill here, but if I’m going to get asked about it down the line, I’d rather be using a listed product I can point to.

What does everyone else use for sealing these types of penetrations? I'm in Colorado, where we deal with significant temperature swings if that plays into your recommendations.

Thank you much for any input!
 
I went through this years ago and you are correct, even "duct seal" is not actually specifically listed for the application. I even contacted DuPont and they would not send me anything saying their products were safe around conductors. I finally just used what was easy and was never questioned.
 
Electricians have been using duct seal for as long as there has been duct seal. Is there any evidence that it actually deteriorates conductor insulation? ConEd has been packing their network protection sleeves with Oakum and duct seal for decades. I would guess that most of those installations still operating today.
 
I can't count how many installs I've done, but 100% of them I used duct seal. I once asked the inspectors at a meeting we have yearly about expanding foam. No, was the resounding answer given. They said it was flammable and couldn't be used to seal electrical penetrations.
 
really appreciate everyone's input. I'm going to stick with duct seal. If the inspector eventually says something I'll burn that bridge when we cross it.
 
Sparro said:
I’m looking for the best product to seal the penetration from my main panel into a single- or multi-family home.
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Not much information there. Is this below ground PVC through the concrete, PVC or other conduit through the siding, SE through the siding, what?

Or, God forbid, a bunch of NM into a panel on the outside of the house? 😖

-Hal
 
I've ripped out many 40 or 50 year old services that had duct seal on the top of the weatherproof SE cable connector with no damage to the jacket of the cable. To me this is just more nonsense.
 
winnie said:
What is the listed use for this product? Does the packaging imply electrical use that the actual listing doesn't support?:
View attachment 2578547
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A few months ago I went on the net to check the temperatures listed for two different brands of Duct Seal. One was only listed for use to +10 degrees F . See Ideal does not list temperature on the above Ideal company Duct Seal. Have seen it crack after years in the sun & cold winters.Gardner Bender Seal rated for -20 to 350 degrees F, Blackburn DX-5 Duct Seal -40 to 250 degrees, Ideal 25 to 120 degrees F, Would not not use Ideal brand in cold climates. For the life if me can not remember the name of Duct Seal that came in heavy brown 5 pound bag that my local supply houses sold. Was also available in one pound. Retired over 6 years and out of supply house products.
 
letgomywago said:
I've heard poly water makes a listed for wire sealing foam product.

I always use duct seal and never spray foam on individual conductors.
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Polywater makes a product for sealing wires, I have used and works well, but requires dispensing gun. Duct seal is fast and readily l accessible.
 
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