I have an older house (1920) and I have been planning on doing some rewiring to get rid of some k + t stuff. Anyway, I just noticed today that there are some irons pipes that used to be part of the heating system. (they are no longer connected + filled with air). Better yet, they run in a perfect vertical run from the basement (where the panel is) all the way up to the attic (where the k + t to be replaced is).

Would it be improper, or otherwise unsafe to just repurpose these unused pipes as electrical conduit ??

  • Pictures, and an accurate description of the pipe (e.g. material, inside diameter, outside diameter, condition of the pipe, etc) might help.
    – Tester101
    Jun 22, 2012 at 11:41
  • It is black iron pipe. I would say about 1/2 inch inner diameter. The outside of the pipe is in good condition (still black, no rust). I am not so sure about the interior.
    – A.R.
    Jun 22, 2012 at 13:19
  • Run conduit or armored cable, with 4 conductors (H/H/N/G) and put a subpanel in your attic. Subpanels!
    – Jay Bazuzi
    Jun 27, 2012 at 18:08

3 Answers 3


Your biggest concern here is going to be the condition of the interior. If they are at all corroded or otherwise rough on the inside they run the risk of damaging the insulation, which can lead to an eventual short and/or electrification of the pipes. Protecting the wire where it enters and exits the pipe is also a concern.

Basically I think you could do it, but I wouldn't recommend it. My gut feeling is that it's too risky.

Since you've got a perfectly straight run - can you possibly remove them and replace them with proper conduit?

  • 7
    If they are large enough diameter, instead of removing them, you could just push a new piece of conduit through them.
    – Dave Nay
    Jun 22, 2012 at 12:12
  • 4
    BX (armoured) cable would probably be simpler than running another conduit inside, although I am still not sure if this would meet code.
    – gregmac
    Jun 22, 2012 at 14:40
  • 2
    This is probably old gas lines used for gas lights. Many old houses from that time period had some electricity in each room (your K&T) but also used gas lights. If they were used for gas and not water the insides might be in decent shape but I would still be inclined to agree with Greebo and just run new conduit.
    – auujay
    Jun 22, 2012 at 16:31
  • 4
    I wasn't aware that one could be "too cautious" when it came to working with electricity. But hey, if you want to play fast and loose with something that can kill you or a family member, who am I to argue? Jun 23, 2012 at 9:00
  • 5
    @TheEvilGreebo Or start a fire in your wall without you knowing! That to me is the scariest prospect here.
    – JNK
    Jun 25, 2012 at 17:57

I guess a big question is: do you need to conform to code?

If you have a building permit out, the inspector may want to see your wiring before you cover it. Your pipe may violate code, and the inspector won't approve the work.

Are you going to sell this house someday, with the wires running into the pipes visible? If so, the buyer's building inspector will probably extract a pound of flesh from you.

Unlike The Evil Grebo, I am not concerned about the safety, as long as the pipe is properly grounded. Any short within the pipe will then trip a breaker. It is no more dangerous than ungrounded conduit would be!

Personally, I would not hesitate to use a "free" channel between floors like this. But I would make very certain the pipe was properly connected to the ground system on both ends.


TLDR; Iron heating pipe is not approved for use with electrical conductors or as sleeves in long runs. Not Advisable.

Sorry to resurrect a dead post, but I want to make sure anyone who falls upon this post see that it is not a good idea nor is it safe. Without quoting codes; equipment and materials must be installed as approved and intended. The iron pipe from what you are describing was not approved for use with conductors. I may venture to say that extra low voltage/Audio visual cable may be OK, but again it really is not approved for that use as a sleeve. As an electrician I would never do it. You run risks that are not thought of; flame and smoke spread if the conductors should catch fire inside the pipe. Also the ampacity of conductors are rated with their ability to dissipate heat while under load. Placing them in an iron pipe not approved for use with conductors throws any theoretical dissipation out the window.

  • 3
    Hello, and welcome to Home Improvement. It's not a problem to give a good answer to an old question, but you should probably take our tour so you'll know how best to contribute here. Sep 10, 2019 at 20:20

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