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300.4 Protection Against Physical Damage. Where
subject to physical damage, conductors shall be adequately
protected.
(A) Cables and Raceways Through Wood Members.
(1) Bored Holes. In both exposed and concealed
locations, where a cable or raceway-type wiring
method is installed through bored holes in joists,
rafters, or wood members, holes shall be bored so
that the edge of the hole is not less than 32 mm
(1
1
⁄4 in.) from the nearest edge of the wood
member. Where this distance cannot be maintained,
the cable or raceway shall be protected from
penetration by screws or nails by a steel plate or
bushing, at least 1.6 mm (
1
⁄16 in.) thick, and of
appropriate length and width installed to cover the
area of the wiring.
Exception: Steel plates shall not be required to protect
rigid metal conduit, intermediate metal conduit, rigid
nonmetallic conduit, or electrical metallic tubing.
(2) Notches in Wood. Where there is no objection
because of weakening the building structure, in
both exposed and concealed locations, cables or
raceways shall be permitted to be laid in notches in
wood studs, joists, rafters, or other wood members
where the cable or raceway at those points is
protected against nails or screws by a steel plate
at least 1.6 mm (
1
⁄16 in.) thick installed before the
building finish is applied.
Exception: Steel plates shall not be required to protect
rigid metal conduit, intermediate metal conduit, rigid
nonmetallic conduit, or electrical metallic tubing.
(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 grom-
mets covering all metal edges and securely fas-
tened in the opening prior to installation of the
cable.