What is the difference between cable diameter and cross section?

The cable diameter is the outside diameter of a pipe. The size of a cable is about the maximum diameter, measured on the outside insulation, determined (unit: mm).

The size of a conductor is defined by the frontal cross section of the metallic part of the wire, without insulation. Contrary to a solid wire, the cross section of stranded wires is the addition of the individual cross sections of all the fine wires forming the stranded string. As this string also contains some spaces between the fine wires, a stranded wire may be up to 20% larger in diameter than a solid wire with same cross section. In Europe the cross section usually is indicated by „mm2“.

In our blog post “Sizes of cables and wires” we address this question in more detail.