I need to know if, when a basement is unfinished and an outlet is on the wall, is it required to put all wires in conduit?

  • 1
    If you decide that this is actually a crawlspace, and not a basement, then the rules are more relaxed.
    – Jay Bazuzi
    Oct 5, 2011 at 18:25
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    It is incredibly cheap and easy to buy some 1x12 lengths and screw them across multiple joists. Then you can staple wires to them. Much better than drilling holes through your joists--that's for lazy electricians and plumbers that don't care about the structural integrity of your house.
    – snuggles
    May 4, 2016 at 0:44
  • 1
    Given that engineered joists are not all that rare these days -- installing a furring board for the run isn't a bad idea to consider. May 4, 2016 at 3:36

4 Answers 4


2005 NEC
ARTICLE 334 Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS

334.15 Exposed Work.

(C) In Unfinished Basements.

Where cable is run at angles with joists in unfinished basements, it shall be permissible to secure cables not smaller than two 6 AWG or three 8 AWG conductors directly to the lower edges of the joists. Smaller cables shall be run either through bored holes in joists or on running boards. NM cable used on a wall of an unfinished basement shall be permitted to be installed in a listed conduit or tubing.

So basically if the cable is on the ceiling, it does not require conduit. If the cable is run along walls, it requires some form of protection. This protection can be conduit, or some other form of protection. You could use a scrap piece of 2x4, for example. Simply attach the 2x4 to the joist, and then attach the cable and box to the 2x4 (following proper NEC procedures of course).

When running cables on the ceiling, only 6/2 and 8/3 (and larger) NM cable can be run along the bottom of joists (perpendicular to joists). Smaller cable must run through bored holes (following 2005 NEC 300.4), or along running boards (boards that run perpendicular to joists e.g. main support beams). When installing cable on the ceiling that runs parallel to the joists, you can attach the cable to the face of the joist (as per NEC 300.4(D)).

As always, check your local codes before installing cable as your location may not follow NEC 2005.

  • 1
    Does this mean sheathed non-metalic cable, 12ga, can't be stapled to edge of joists?
    – rcav8r
    Oct 5, 2011 at 19:46
  • @rcav8r: Correct, that is prohibited. If you are still in doubt you can post a picture to show your situation.
    – auujay
    Oct 5, 2011 at 21:54
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    What about running along a joist? Either on the bottom or on the side. Is that permissible? Jan 4, 2012 at 14:20
  • @ChrisCudmore See NEC 300.4
    – Tester101
    Jan 4, 2012 at 14:44
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    "...on a wall...a listed conduit or tubing" Why do you say "...along walls...You could use a scrap piece of 2x4"? Is that a listed conduit or tubing? Apr 26, 2020 at 23:38

OK, Tester is absolutely right and gave you the proper reference. Now I will give you the practical solution. 14 or 12 ga romex can be run along the wrap beams or center beams. It cannot be run across joists without drilling through them. Assuming you meet those requirements and get to the wall, you have two choices. You can run EMT down the wall and use metal boxes for outlets, or you can ramset wood 2X4's down the wall and staple the wire to it and use a proper surface mounted outlet box and GFI receptacles. Both will meet code in an UNFINISHED BASEMENT. I stress unfinished, because rules change if you are going to put up walls etc. The perfered method is Conduit, but either will work.

  • 1
    Can BX/AC be used instead?
    – Steven
    Jan 3, 2012 at 18:40
  • Yes - BX is basically flexible conduit.
    – RQDQ
    Jan 6, 2012 at 15:40
  • Why can you staple NM to a 2x4 running down an unfinished basement wall without protection such as conduit or EMT? Do you consider it not subject to physical damage? NEC 334.15 quoted in this answer seems to require it. Jun 4, 2020 at 5:51

Yes, if the wires are "exposed" then they must be protected. Romex is fine when it is inside a wall/ceiling/floor because it is protected from puncture/cuts/etc. but if it is just running along the exposed walls of a basement that is not up to code.

That said, there are many basements that have this "problem", mine included. If I had kids I might be worried about it but I may finish the basement eventually and just fix it then. It is something my home inspector mentioned before we bought the house.


It is all right to run cable through holes drilled in joists. The thing is that the hole should be drilled in the center of the joist (not near the top or the bottom) to preserve strength of the joist.

This is because the upper part of the joist is under compression, the lower part under extension. The middle part is simply sitting there: it will weaken the beam almost not at all to have a few small holes drilled in the center. In fact, such holes might even relieve stresses which cause cracks in the wood to propagate.

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