Construction of cable cores according to IEC 60228
According to IEC 60228, conductors of insulated cables are subdivided into 4 classes.
- Class 1: solid conductor, the core is formed by one single wire with a diameter up to 6 or 10 mm2 (also denoted by the letter U)
- Class 2: stranded conductor intended for fixed installation: for cores with a diameter over 6 or 10 mm2, the core is usually formed by a plurality of thin wires (also referred to by the letter R)
- Class 5: flexible conductor: the core is formed by a large number of thin wires
- Class 6: very flexible conductor.