Protect Cable From Metal Truss Plates
334.23 In Accessible Attics.
The installation of nonmetallic sheathed cable Type NM-B in accessible attics or roof spaces shall also comply with 320.23.
320.23 In Accessible Attics.
Type AC cables in accessible attics or roof spaces shall be installed as specified in 320.23(A) and (B).
(A) Where Run Across the Top of Floor Joists.
Where run across the top of floor joists, or within 2.1 m (7 ft) of floor or floor joists across the face of rafters or studding, in attics and roof spaces that are accessible, the cable shall be protected by substantial 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.
(B) Cable Installed Parallel to Framing Members.
Where the cable is installed parallel to the sides of rafters, studs, or floor joists, neither guard strips nor running boards shall be required, and the installation shall also comply with 300.4(D).