[been40]

I have air-conditioning #8 romex wire going from basement wall (wall is wood material)
To the outside into a outside cutoff switch. I noticed air penetration is an issue with the
One inch hole that the previous electrician drilled to the outside for this. I used caulking with little bit of silicon a few years ago to stop the air penetrations from this one inch hole.

Yesterday, when I ripped the insulation off to replace it, I noticed the caulking is hard rock
And solid, and I thought it can damaged the #8 romex wire if left the way it is with the
Expansion and contractions of the wood. I am hoping I can peal this old caulking off
(carefully), and put in something else to fill around the wire.

Is pure silicon caulking, like from GE (silicon I or II) they sell at the home centers
A good thing to use to fill the one inch hole that the #8 romex wire is going through?
Should I be worried about chemical reactions between the romex NM-B wire and
The caulking ?

What do you suggest/recommend? Keep in mind that, this hole is going from inside
To the outside, so it needs to be water proof.

[stanfortyman]

I use 100% silicone. It lasts for years.

[been40]

I use 100% silicone. It lasts for years.

Thanks for your response.
Question: At the home centers, they seem to have silicon caulking labeled
As: for windows & doors, siding, etc. I don't know what's the difference
Between these categories, since they are all outside use any way. Is it the amount
Of silicon in it that they label it that way? What should I look for at the
Home centers, to get the 100% silicon you have mentioned?
Thanks again,

[stanfortyman]

I honestly don't know what they add to silicone to make one for outdoors, one for kitchens and baths, and one for windows and doors... especially when they are all just 100% silicone. :confused: