IEC 60228

As of 2023[update] the current version is Third Edition 2004-11[1] Among other things, it defines a set of standard wire cross-sectional areas: In engineering applications, it is often most convenient to describe a wire in terms of its cross-section area, rather than its diameter, because the cross section is directly proportional to its strength and weight, and inversely proportional to its resistance.

The cross-sectional area is also related to the maximum current that a metallic wire can carry safely.

The nominal (see below) cross-sectional area for standard conductors including the following: The maximum permissible resistance per unit length (in ohms per kilometre – Ω/km) of each conductor size, class and type (both plain copper and metal coated) This document and its precursors were created due to a need for a standard definition of cable conductor size.

Instead this document describes conductors by their nominal size, determined by resistance rather than physical dimensions.

This is a key distinction as it makes a standardized definition of conductors based solely on their electrical characteristics.