I've taken some ceiling tiles down in prep for running network cables through the house and found some questionable electrical work. As I understand it these wires probably wouldn't be okay even if the ceiling was completely open because they're 12 AWG and running perpendicular to the joists, but I want to confirm whether or not these are supposed to be run through holes in the joists.

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  • @isherwood How does this relate to my question? Theirs is about running above joists in an non-habitable space. The answer that cites code only talks about the requirements for holes if that is what is being used, not when holes are called for.
    – Logarr
    Apr 22, 2022 at 20:08
  • It does seem like a question deserving of it's own answer. Cables in walls need protection, either far enough inside the wall or steel plates. Cables above eight feet do not need as much protection, if any. Ceiling is usually eight feet or more and most people do not drive screws or nails into their ceilings. Some do though(hanging plants), so do the cables need protection?
    – crip659
    Apr 22, 2022 at 20:33
  • @crip659 My basement ceiling is 7'6" from floor to tile. Either way, when looking at the sections for unfinished basement wiring there wasn't anything about how tall the ceilings were before the code didn't matter.
    – Logarr
    Apr 22, 2022 at 20:36

1 Answer 1


This is a simple one when exposed smaller gauge requires a backing board to be run perpendicular to the joists. There is a pretty picture exhibit 334.1 this is for crawl spaces and basements code gives no height restrictions but local code may.

This example where it was covered was a code violation the cable required a nail plate at each joist in this example because it is less than 1-1/4” from the face of the joist (so you are correct it was a bad thing to cover)

The best way to fix something like this is to pull the cable out drill a 3/8 hole so the edge of the hole is at least 1-1/4 inch back from the face of the joint and pull the cable through the bored holes. That could bring it up to code.

  • Excellent. I figured it was wrong but wanted to make sure. I was already going to be taking down a lot of tiles to run some network cable but now I’ll be taking down more and drilling a second set of holes. Thank you!
    – Logarr
    Apr 23, 2022 at 0:00

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