I'm used to making sure electrical wire is setback 1 1/4 inch from the face of a wood stud, but what are the requirements (US NEC) for 2 1/2 inch steel studs? They appear to come punched out for wires or plumbing, but wouldn't provide enough setback to protect the wiring. The steel stud is designed for a screw to go through it. Are there thicker steel protection plates designed for steels studs, or would that even be necessary?
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Are you using NM Cable?– NoSparksPleaseCommented Mar 13, 2021 at 16:01
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2@NoSparksPlease, that's right, the plan was standard SIMpull non-metallic jacket wire. Sorry, should have clarified.– escapethecubeCommented Mar 13, 2021 at 16:10
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1 Answer
The NEC language for metal studs is different, it doesn't actually say 1.25", but enforced much the same.
300.4(B) Nonmetallic-Sheathed Cables and Electrical Nonmetallic Tubing Through Metal Framing Members.
(1) Nonmetallic-Sheathed Cable. In both exposed and concealed locations where nonmetallic-sheathed cables pass through either factory- or field-punched, cut, or drilled slots or holes in metal members, the cable shall be protected by listed bushings or listed grommets covering all metal edges that are securely fastened in the opening prior to installation of the cable.
(2) Nonmetallic-Sheathed Cable and Electrical Nonmetallic Tubing. Where nails or screws are likely to penetrate nonmetallic-sheathed cable or electrical nonmetallic tubing, a steel sleeve, steel plate, or steel clip not less than 1.6 mm (1∕16 in.) in thickness shall be used to protect the cable or tubing. Exception: A listed and marked steel plate less than 1.6 mm (1∕16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted.
Sometimes you can drill an extra 1/4" hole to use a zip-tie to pull the cable against one edge to require just one plate or zip-tie toward concrete wall if stud if stud is just furring.
The wording of the previous paragraph that covers wood leaves no wiggle room to not use nail plates on edges not likely to get nailed or screwed to like double walls or furring.
answered Mar 13, 2021 at 16:14
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Thanks @NoSparksPlease. So is the reason factory punch-outs exist on 2 1/2 steel studs is for armored cable? Commented Mar 13, 2021 at 16:31
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Holes are used for other trades too. I try to stay away from "why", but you seem to be on target since the Articles for AC and MC cables refer to 300.4 (A) for wood and there is no reference to a metal framing paragraph in those Articles. I have seen local jurisdictions adopt local ordinances adding related requirements. Commented Mar 13, 2021 at 16:55
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Are there steel plates specifically designed to protect NM passing through factory openings in metal studs? Commented Mar 13, 2021 at 17:35
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@JimStewart Not aware of steel, plastic protectors work and are less than a quarter a piece. Commented Mar 13, 2021 at 18:23
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I meant are there plates specifically for metal studs to stop drywall screws from piercing NM like those used on wooden studs to protect wires and plumbing. Grommets protect NM from sharp edges of holes in the metal studs. Are there steel tubes that fit in these holes in metal studs? Or would plates be pointless since grommets center the wire and drywall screws are short enough to just barely go through the edge of the metal stud? Commented Mar 14, 2021 at 11:12