FAQ

Material taken from the National Electric Code

is reprinted with permission

from NFPA 70

, 2023 edition. National Electrical Code

NEC

Text

comply with the following as applicable.:

(1) Screws shall be machine type with blunt ends.

(2) Other fasteners shall have blunt ends.

(3) Screws attaching a cover shall extend no more than 10

mm (3/8 in.).

(4) Screws or other fasteners, other than in (3), penetrating a

cover shall extend no more than 8 mm (5/16 in.).

(5) Screws or other fasteners penetrating a wall of a box

exceeding 1650 CM

(100 in.

) shall extend no more than

6 mm (1/4 in.), or more than 11 mm (7/16 in.) if located

within 10 mm (3/8 in.) of an adjacent box wall.

(6) Screws or other fasteners penetrating the wall of a box

not exceeding 1650 CM

(100 in.

) and not covered in

314.23(B)(1) shall be made ush with the box interior.

(7) Screws or other fasteners penetrating the wall of a

conduit body shall be made ush with the conduit

body interior.

Exception to (3) through (6): A screw shall be permitted to be longer if the

end of the screw is protected with an approved means.

Expert Analysis

A new section has been added to address the

possibility of screws and fasteners damaging conductors

within boxes. In all instances the only permitted style

of screws are the type with machine threads and a

blunt end. This reduces the likelihood of damage to

conductors due to coarse threads and sharp points

typically found on sheet metal screws. The penetrating

length varies depending on the application and location.

Any screw sanctioned by the equipment manufacturer

will be automatically acceptable. Other screws, such as

those used to attach identifying medallions, must have

machine threads and have blunt ends.

continued on page 62