Bending radius is the minimum curve a fiber optic or electrical cable can withstand without risking damage or performance loss under specified tension.
In structured cabling, the bending radius indicates how tightly a cable may be curved during routing or pulling before mechanical stress compromises its integrity. The radius is measured from the curve’s center to the cable’s inner edge and depends on the cable’s construction and materials. Manufacturers typically provide both a dynamic bending radius, measured while under pulling tension, and a static bending radius, measured when the cable is at rest. Exceeding these limits can deform conductors, disturb shielding, or damage insulation, leading to attenuation or long-term reliability issues. Following bend radius specifications helps maintain system performance in AV, security, automation, and low-voltage networks.
Bending radius guidelines are addressed by the Telecommunications Industry Association (TIA), International Electrotechnical Commission (IEC), and Underwriters Laboratories (UL).
The formalization of bending radius specifications grew with the adoption of fiber optic and high-frequency data cables, where even small deformations could cause significant attenuation and signal loss. This drove the need for clear industry standards.