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 Failed cables often show these symptoms:
- Corkscrew or pigtail effect where cables twist in themselves
- Knotting of conductors underneath the cable jacket
- Cables twist around one another
- Cable stick out between crossbars of cable carrier and get caught in the radius
- Loss of conductivity through plain breaking of conductors
Why do cable fail?
- Cable is not designed for constant flexing
- Cable is too tight in the carrier
- Cable's actual bend radius is smaller than recommended
- Cable carrier design is not cable-friendly
Many industrial cables are not designed for constant flexing. They will corkscrew and knot very
quickly, especially when run at tight bending radii. Some cables feature a cotton tape between
the conductors and the outer jacket; due to the constant bending, that tape may bunch up
underneath the jacket and crimp the conductors.
Cables with a built-in twist develop corkscrews easily. The inherent twist is amplified by the
constant flexing of the cable until the conductors break.
The ideal cable for use in cable carrier should be PVC/PUR/TPE jacketed and not made of rubber or neoprene.
The latter two materials are too sticky and do not enable the cable to easily move with the
carrier. This too can contribute to cables knotting up.
Also, cables should not be pulled tight when installed in a cable carrier. Often times this causes the cable to stretch over the inner crossbar at the radius section of the carrier until the conductors break. This should be
checked when the carrier is at its maximum free span (unsupported, no sag).
Many industrial cables require a bend radius too large for most machine applications. Forcing
the cable to run at a tighter radius will shorten its life substantially. A cable designed for
tight bending radii, like Chainflex continuous-flex cables, must be selected.
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