All the visible cables in my attic are old armored cables, thus protected from possible critters trying to chew them (I've had squirrels there before) and other forms of direct impact.

As I'm doing some rewiring and have a large amount of leftover NM (romex) cable, I was wondering if I can run that just sitting on top of and secured to the joists in the attic, like the current armored cable is. I can certainly go buy MC cable (metal-clad, which is like a modern version of my archaic armored BX that has aluminum wire and no ground) but would rather use what I have left over.

  • Is there a permanent ladder or stairs leading to the attic? Will the cables be within 6 feet of the point of access? This answer might be helpful.
    – Tester101
    May 28 '16 at 2:32
  • No permanent stairs, only a ceiling hatch in one of the room's closet that is used from a stepladder. The closest the cables would be to that would be about 6-7'
    – amphibient
    May 28 '16 at 2:36
  • 2
    then no protection is required. However, if you've got critters trying to chew your wires, you might not want to use it.
    – Tester101
    May 28 '16 at 2:38
  • Currently the attic is sealed pretty well so no significant critters should be able to get in. I doubt mice go there as there is no food plus they're too little to chew NM cable. Maybe a rat but I've never had rats in my house
    – amphibient
    May 28 '16 at 2:40
  • 1
    I think NM will work, you don't have critters now but it would be code to put it in. I have repaired wiring where a squirrel ate to death on honey that was dripping on old braided lines. Code requires wire size not critter protection.
    – Ed Beal
    May 28 '16 at 7:52

Yes. NM cable may be exposed in attic.

This is very common in modern dwellings. Armored cable / MC is not necessary in your case.


Protection is required for NM cable within 6 feet of the attic scuttle hole.

From the 2014 NEC (emphasis added on the last sentence):

320.23(A) Cables Run Across the Top of Floor Joists. Where run across the top of floor joists, or within 2.1 m (7 ft) of the floor or floor joists across the face of rafters or studding, the cable shall be protected by guard strips that are at least as high as the cable. Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 1.8 m (6 ft) of the nearest edge of the scuttle hole or attic entrance.

Or just make sure the cable is not within 6 ft do the scuttle hole.

Good luck!

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