Are there any code/cost reasons we couldn't run BX/romex to our attic through an old disconnected chimney? The chimney in question

Long Question:

I will be closing on a house shortly and there is a hole in the attic floor where the house's original chimney used to run (the chimney has been removed down to the attic floor). The attic is finished but run-down and we plan to eventually renovate it; but there is limited electrical. Before we move all of our furniture in we were going to have a contractor refinish the floors and replace any soft spots or holes, but this seems like a perfect chase for electrical and I was considering bringing in an electrician to run an extra circuit to the attic before we cover it up. Would there be a code problem running through an old chimney like this? Or alternatively would there be another reason this would be worse than trying to fish a cable up past two stories of nice old lath and plaster walls?

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    Seems like a super handy place to easily drop some conduit down. I'd go with that just to protect the outer jacket of any NM-B you might run. Of course, if you go that route, you'd want to run individual wires, not cable through the conduit. You could also grossly oversize the conduit (or run a couple) for future expansion (1 new circuit seems to be underplanning) to make things even easier. Check with your electrician, once you've got him hired. (I'd also wait for one of the electricians to confirm there are no code issues.)
    – FreeMan
    Commented Jul 20, 2020 at 15:00
  • Disconnected how? In particular, is there any path from the section you want to use to "outside" ? Because if so, you'll definitely have to consider the run to be "exterior" so far as wire type goes. Commented Jul 20, 2020 at 15:23
  • @CarlWitthoft presumably it used to go outside through the roof, but no longer does. The is also a hole that exposes the interior of the chimney to the basement (I believe where the old boiler connected) but that is in the dead center of the house, nowhere near the "outside"
    – Steve Cox
    Commented Jul 20, 2020 at 15:25
  • @Steve then it sure sounds like it's no different from fishing a cable thru walls. Commented Jul 20, 2020 at 15:28
  • That looks like a electrical chase to me :)
    – Ed Beal
    Commented Jul 20, 2020 at 18:11

1 Answer 1


It isn't a chimney if it is disconnected. Yes.

As for what you need to support the cables. This is really on the whim of a local inspector. As mentioned in comments I have never had an issue dropping NM straight down plumbing walls in the interior of a house. I made right before the drop and right after the drop very secure.

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    This does not provide any information on safety or code requirements. Commented Jul 20, 2020 at 15:23
  • Carl - There isn't code listings for defunct chimneys - code isn't infinite examples of what you can do it focuses on what not to do. The same restrictions would be the same if running through any wall in your house.
    – DMoore
    Commented Jul 20, 2020 at 15:27
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    Hi. With 35k+ of rep, you should know how to give an answer by now. This is a fragment; would you enhance it to an answer? Commented Jul 20, 2020 at 16:12
  • Dmoore, in my jurisdiction the chimney has to be permanently disabled so it can not be used in the future for example as a gas vent, or for a wood stove. The cap has to be sealed permanently requiring mortar and slabs to be in place not just a metal cap then it could be used in my jurisdiction and the op identified that it is non functional. where you might run into trouble is length of wire un supported , you can fish wires in walls but the inspector may have issues with more than 1 but the op said down to attic floor I don’t think worth a down vote + the question was well framed ++
    – Ed Beal
    Commented Jul 20, 2020 at 16:36
  • @EdBeal - If I am getting the question... the "chimney" isn't sticking out of the roofline. This is simply some bricks with a gap as part of the house. I agree it would need to be capped if it had access from either side but that doesn't seem to be in the question. As for support there are a ton of variables and ways to do this and a lot of it will be at the whim of local inspector. I have never had issues dropping NM down from attic on plumbing walls to basement without support for that ~10 feet.
    – DMoore
    Commented Jul 20, 2020 at 16:52

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