What is the typical bend radius rule for fiber cables?

• A. Typically at least 10 times the cable diameter; tighter bends increase attenuation and break risk.
• B. Typically <= 2 times diameter.
• C. Bends have no effect on attenuation.
• D. Only bend radii matter for schedule.

Answer: (A)

Bending a fiber optic cable changes how light travels inside it. Tight bends push light toward the outer edge and can cause light to leak out of the core or be scattered, which increases attenuation. They also apply mechanical stress to the fiber and its jacket; if the bend is too sharp, that stress can create microcracks or other damage that worsens loss or leads to breakage. Because of this, a common rule of thumb is to keep bends at least about 10 times the cable diameter. This gentle radius helps keep light confined within the fiber and protects the cable from damage, maintaining low attenuation and longer life.

Tighter bends, like those only 2x the diameter, would significantly raise losses and risk damage. Saying bends have no effect on attenuation is incorrect because bending is a primary cause of loss in fiber. And noting that bend radii matter only for scheduling ignores the direct impact on signal integrity and reliability of the connection.