I had to break a hole through a 2-layer thick brick wall to run drain pipe for some new plumbing. This is the original foundation wall of the house, and I broke through into inside space underneath an addition - both sides are interior. Since the hole ended up bigger than needed for that, I'd also like to use it to run wiring through.

I don't want to just pull NM-B through the opening, since there's a high likelihood of damaging the outer sheath of the cable, so I'd like to put a few pieces of 1-1/2" or 2" (whatever will fit) Schedule 40 DWV pipe (white) in the wall for protection before I fill the rest of the opening with mortar.

Since this run will be 8" maximum, and I'm simply using it as a chase to protect the cable during the pull and the bricks will actually be providing the protection from any physical damage, am I allowed to use DWV or do I have to use conduit?

  • Imagine code and some inspectors would say no. Think this is one question only your inspector can answer after a nice cup of coffee and cookies(homemade).
    – crip659
    Commented Feb 4, 2023 at 15:58
  • 2
    Well, he is stopping by any minute now to "pre-inspect" my DWV before I start gluing it up. Advantages to living in a very small town. ;) We had a nice chat when he was here for framing inspection. I thanked him for plowing our driveway ~20 years ago after he'd come by to plow the street and left everyone buried with that big pile of snow. My son (who knows no strangers) had made a friend of him, so he did us a favor! :)
    – FreeMan
    Commented Feb 4, 2023 at 16:02

2 Answers 2


Not sure why this would be a problem. You are allowed to drill through a brick wall and run the cable through it without conduit. You've just got a bigger hole in the wall and want to make it smaller with the DWV. If this is an outside wall, the inspector might not like the NM cable and will want UF instead.

  • Good point that I failed to mention. This is a foundation wall, but it's all "inside" as it's a wall between the original house and an addition. Updated the question to indicate that.
    – FreeMan
    Commented Feb 4, 2023 at 18:33

A wall isn't considered water-tight, although in your case it's an interior one (but then again you're applying mortar to it, so... wet.) Also, the drilled hole can abrade the sheathing. Needs a conduit in any event.

ABS DWV pipe isn't normally used for conduit. Instead, Gray Sch. 40 PVC conduit would be a better, likely-to-pass choice. Gray PVC is suitable for both dry and wet locations.

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