Cables with layered strands, 7 or more cores and a cross section of >1.0 mm² are especially at risk on long travels:
The so-called corkscrew effect. This has an adverse effect on the cable’s overall structure and core breakages can occur.
Cores wound in bundles counter this effect. Cable bundles with previously layered strands and a minimum of 3 cores are wound in short pitch lengths around a centre element of high tensile strength. The forces and effects described above are thus compensated for.