NEC 300.4 — Protection Against Physical Damage (Bored Holes, Notching, Stud Plates)
NEC 300.4 sets the rules for protecting cables from physical damage during framing. Bored holes need clearance from stud edges; cables run through notches need steel nail plates. The rule that catches every rough framer who tried to "help" the electrician.
NEC 300.4 is the rule that decides whether your rough-in passes — it sets the protections required when cables pass through wood or metal framing.
Bored holes (300.4(A)(1)): cables passing through bored holes in wood studs, joists, or rafters must have AT LEAST 1¼ inches of wood between the closest edge of the hole and the FACE of the framing member that drywall will be screwed to. If the hole is closer than 1¼ in, you must install a steel nail plate at least 1/16-inch thick covering the area where the cable passes.
Notches (300.4(A)(2)): cables run in notches in wood studs, joists, or rafters require a steel plate (1/16-inch minimum) covering the notched area. Notching weakens the framing AND exposes the cable to nails — both problems solved by the steel plate.
Why this matters in residential renovations: the most common installation in older Hudson County homes is running new circuits through existing finished walls or up through balloon-framed studs. If the existing framing has notches or holes too close to the surface, you need plates everywhere. Inspectors WILL count plates on a rough-in.
Cables through metal framing (300.4(B)): when cables pass through metal studs, the holes must be protected with listed bushings or listed grommets to prevent the metal edges from cutting into the cable jacket. Standard plastic grommets (not listed for this) are a fail.
Cables under metal corrugated sheet roof decking (300.4(E)): cables (NM, AC, MC, FMC, etc.) run under metal corrugated decking must be at least 1½ inches from the nearest surface of the deck. Common rough-in failure on second-floor exposed-deck additions.
Parallel runs (300.4(D)): where cables are installed parallel to framing members, they must be installed not less than 1¼ inches from the nearest edge of the framing member, OR be protected by a 1/16-inch steel plate. Same 1¼-inch rule as bored holes.
Practical Hudson County rough-in tip: carry a box of stamped steel nail plates (cheap, 1/16-inch, fits a 2x4 face) and apply them liberally on every borderline situation. The cost is negligible; rough-in failures are expensive.
This guide is an educational summary written by a licensed NJ master electrician. It is not a substitute for the National Electrical Code or for the judgment of your local AHJ. For real permit work, verify every code interpretation with your authority having jurisdiction and a licensed electrician of record.