What is birdcaging in cable systems, and how do manufacturing processes and installation practices contribute to this structural defect?

Birdcaging refers to the unintended unwinding or distortion of stranded cable conductors or armor layers, characterized by individual strands rising or warping out of their original helical configuration. This phenomenon arises from mechanical stress imbalances during both production and handling: in manufacturing, excessive torsion from misaligned sheaves or uneven tension in strand bundling can disrupt the structural integrity of non-rotational cables, causing strands to separate. During installation, improper unreeling techniques—such as ignoring torsion release in armored cables—introduce axial compressive loads that radially expand armor wires, splitting outer sheaths and exposing internal components.   The defect poses critical risks: compromised insulation integrity accelerates electrical degradation, while distorted conductors increase resistance and potential for overheating. Prevention requires precision in manufacturing (calibrated tension controls, anti-rotation sheave alignment) and installation protocols (controlled unreeling to manage residual torsion, proper drum handling to avoid axial stress). Post-suspicion protocols mandate immediate inspection to assess structural viability, ensuring compliance with safety standards and avoiding catastrophic failure in power distribution or industrial systems.