IEC 60228:2023

Overview

IEC 60228:2023 - "Conductors of insulated cables" - is the fourth edition (2023) International Electrotechnical Commission (IEC) standard that defines the nominal metric conductor sizes, construction classes and core requirements for conductors used in electric power cables and cords. The standard covers conductor cross-sectional areas from 0.5 mm² up to 3 500 mm², and addresses solid, stranded, Milliken and flexible conductor types in copper, aluminium and aluminium alloy. IEC 60228 is a horizontal reference intended for cable product standards, manufacturers, designers and testing laboratories.

Key topics and technical requirements

• Nominal cross-sectional areas: Standardized metric sizes for power and flexible conductors (0.5 mm² to 3 500 mm²).
• Conductor classes and constructions: Definitions and requirements for:
  • Class 1 - solid conductors
  • Class 2 - stranded conductors (including compacted and Milliken constructions)
  • Classes 5 & 6 - flexible copper conductors
• Numbers and sizes of wires: Rules for wire counts and strand dimensions for different conductor classes.
• Electrical resistance values: Specified resistance limits and measurement methods for conductors; guidance on correction for temperature.
• Materials and mechanical properties: Requirements for copper, aluminium and aluminium alloy conductors, including tensile strength limits for solid and stranded aluminium conductors.
• Compliance and testing: Clauses and an informative annex structure to support verification - Annex A covers measurement of resistance (normative), Annex B provides temperature correction factors (informative) and Annex C offers guidance on dimensional limits of circular conductors (informative).
• Scope boundaries: Not applicable to telecommunication conductors; where relevant the cable‑type standard specifies applicability to particular cable constructions. The standard generally applies to conductors in the finished cable.

Applications and who uses IEC 60228

IEC 60228 is used by:

• Cable manufacturers for conductor specification, production and quality control.
• Electrical and power system designers when selecting conductor sizes and classes for fixed installations and flexible cords.
• Test laboratories and certification bodies for resistance measurement, dimensional checks and compliance testing.
• Procurement and standards committees drafting product standards and national regulations that reference conductor characteristics.
  Practical applications include low- and medium-voltage power cables, industrial flexible cords, repair/maintenance specifications and cross-border procurement where harmonized conductor data is required.

Related standards

• IEC Guide 108 - horizontal publication status guidance.
• IECEE OD-5014 - instrument accuracy limits (referenced).
• Other IEC cable product standards from IEC TC 20, which reference IEC 60228 for conductor requirements.

Keywords: IEC 60228, conductors of insulated cables, conductor cross-sectional area, stranded conductors, Milliken conductor, copper conductor, aluminium conductor, resistance measurement, temperature correction factors.