Cabling
Bend Radius
The minimum radius a cable can be bent to without degrading signal quality or risking physical damage. Exceeding it permanently impairs the cable.
Every cable type has a minimum bend radius specification — the tightest curve it can safely make. Bend tighter than the spec and you risk crushing the conductor, cracking the insulation, or in the case of fiber optic cable, microbending the glass core in ways that scatter light and increase attenuation.
Typical minimum bend radii:
- Cat6 Ethernet cable — 4x the cable diameter (roughly 1 inch). Common violations: sharp 90° bends around conduit corners, cables pulled tight over a rack edge.
- Cat6a (shielded) — larger minimum radius due to thicker construction, typically 8x cable diameter.
- Single-mode fiber — 30mm (about 1.2 inches) at installation; some bend-insensitive variants rated down to 7.5mm.
- Multi-mode fiber — similar to single-mode for most types.
The practical implication: when routing cables through tight spaces, cable managers with proper radius guides, or J-hooks with the correct size, aren't just organizational — they protect signal integrity. A cable that looks fine but has been bent too sharply may perform fine at first and degrade over time as the insulation fatigues.