Code Change Summary: New code section to address Nonmetallic Sheathed cable (NM) entries.

In the 2023 NEC^®, new Section 334.19 was added to require the cable sheath of nonmetallic-sheathed cable to extend at least ¼ inch beyond any cable clamp or cable entry. This change provides solid code language for a well-known practice that has been an industry standard for years. The importance of this new code language is that it is general and not specific to the type of enclosure the cable enters, or whether the cable is exposed or concealed.

This new code change makes it clear that regardless of the box, or enclosure type used, if a nonmetallic sheathed cable covered by Article 334 enters with a cable clamp or other entry, at least ¼ inch of the cable sheath needs to extend beyond the entry before the sheath is stripped back to expose the conductors. This ensures sufficient protection from abrasion for the conductors inside the cable sheathing.

Existing Section 314.17(B)(2) requires at least ¼ inch of cable sheathing to extend beyond a cable clamp into an enclosure but pertains only to installations involving a box or conduit body. Technically, without the new code language, there was nothing addressing NM cable entries into a panelboard cabinet covered in Article 312 unless the installation was a nonmetallic sheathed cable entering the top of a surface mounted enclosure through a raceway as covered in the exception to Section 312.5(C).

Section 334.15(C) has a similar existing requirement for exposed work using NM cables in unfinished basements and crawl spaces. This section applies when nonmetallic-sheathed cable is installed through conduit or tubing and requires at least ¼ inch of cable sheathing to extend through the conduit or tubing and into the outlet or device box.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2023 NEC^® edition of NFPA 70.