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how to seal around wires brought through a basement wall???

Posted by jaansu (My Page) on
Fri, May 25, 12 at 13:00

I will be bringing new lines from my basement to under my deck, either by hammerdrilling through the cement foundation or through the sill plate above it. Once I push the UF wires through the hole, what is the standard technique for sealing around the wires? Silicone caulk? Does code require a box to be the exit point for the wires on the exterior wall? I can't seem to find much about this.


Follow-Up Postings:

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RE: how to seal around wires brought through a basement wall???

If it is a larger hole- then fill most of it with foam and finish the part closer to exterior with an Epoxy putty. I think HD sells a Locktite 5min Epoxy putty. It's water proof and very strong. If you keep the hole small, perhaps just the epoxy putty will be enough. It will last a lot longer than the silicone.

Do you have pictures of the exit spot and where you are running the wire to?


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RE: how to seal around wires brought through a basement wall???

Small hole duct seal on the outside, and foam on the inside. should do the trick.


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RE: how to seal around wires brought through a basement wall???

Polyurethane caulk and duct seal.


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RE: how to seal around wires brought through a basement wall???

Thank you. I'll pick up the products at HD and be ready once the deck is up and I can get to the spot.


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RE: how to seal around wires brought through a basement wall???

Duct seal makes a good temporary filler.

It can be used as a permanent filler (and has been for many years) but a topping of polyurethane caulk in grey often blends in better and provides a better seal.


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RE: how to seal around wires brought through a basement wall???

How about if I came through wood/siding instead of concrete? Would duct seal and caulk still be the best means to close the hole? While I'm on the topic, are there limits to how many lines I can push through depending on the size of the hole? Perhaps I should make a larger hole than needed for thermal issues?


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RE: how to seal around wires brought through a basement wall???

Duct seal can stain wood as oils leach out.
They can come up through the paint from the cut edges.

I use just poly caulk with some backer rod as a filler if required.

You can fold the backer rod over a few times to increase the size.
It is just there to help stop the caulk form flowing in undesired directions.

Some caulk is thick enough to simply squirt in and build up.

It is not a large enough distance of close contact to be a real issue in typical residential wiring with the small temperature rise in almost all applications.

You might have an issue in the desert in an attic or commercial applications near heat generating equipment.


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