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. The cable bending radius is the minimum radius a cable can be bent without damaging it. When bent too sharply, helical metal tapes can eparate. concerned on the datasheet too. Each subsection, for example BS7870-4. 10, also has its own specific Annex A which provides more explicit nformation for that cable type. In order to maintain a certain margin of safety, manufacturers, standards and regulations establish minimum values depending on the type of cable, the application and the instal ation conditions.