334.24 Bending Radius. (2024)

Code Change Summary: New requirements added regarding the bending radius of Nonmetallic Sheathed cables.

During the first draft meetings of the 2023 NEC^®, a public input to provide rules on the minimum required bending radius for Nonmetallic Sheathed cables was accepted but modified to clarify the proper intent.

The previous language in Section 334.24 required bends in Types NM and NMC cable to be no smaller than five times the diameter of the cable. The bend was measured as the radius of the curve of the inner edge of the cable.

For a flat NM cable, the thickness of the cable is less than the width of the cable which left the previous code section a bit unclear when determining cable diameter.

The public input for Section 334.24 was to use the thickness of flat NM cables to determine the cable bending radius.

The code panel agreed that there should be language in Section 334.24 to clarify how to determine the bending radius for flat cables, but they made it clear that the major diameter of a flat cable must be used to determine the bending radius, not the cable thickness.

In the 2023 NEC^®, Section 334.24 requires the radius of the curve of the inner edge of any bend in type NM or NMC cables to be at least five times the diameter of the cable. For flat cables, the major diameter dimension of the cable is used to determine the bending radius.

A similar code change also occurred in Section 338.24 for type SE and USE cables, and Section 340.24 for type UF cable.

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.