EN IEC 60228 Conductors of Insulated Cables

The “EN IEC 60228 Conductors of Insulated Cables” standard, based on a European standard and subsequently published by the International Electrotechnical Commission (IEC), describes nominal cross-sectional areas ranging from 0,5 mm² to 3500 mm² for conductors in a wide variety of electrical cables and cords. Requirements regarding the number and dimensions of the strands, as well as resistance values, are also specified. These conductors include single-strand, multi-strand, and copper, aluminum, and aluminum alloy conductors used in fixed installation cables, as well as flexible copper conductors.

This standard does not apply to conductors intended for telecommunications. The applicability of this standard to a particular cable type is as specified in the cable type standard. Unless otherwise specified in a particular clause, this standard relates to conductors in a finished cable, not to conductors manufactured or supplied for inclusion in a cable. The conductors described in this standard are specified in metric dimensions.

The informative appendices provide additional information, including temperature correction factors for resistance measurement (Appendix B) and guidance on the dimensional limits of circular conductors (Appendix C).

In short, the EN IEC 60228 standard is an international standard that specifies the nominal cross-sectional area and conductor resistance of insulated cables and cords used for power distribution, control, and communication purposes. This standard applies to:

• Copper and aluminum conductors.
• Solid, multi-stranded, flexible, and extra-flexible conductors.
• Conductors for fixed installations and flexible cables/cords.

The following are outside the scope of this standard:

• Conductors for telecommunication cables (covered by other standards).
• Special conductors (e.g., heating cables, aircraft cables).

The EN IEC 60228 standard defines four main classes of conductors according to their flexibility:

• Class 1 Solid conductor: Typical structure, single solid wire (circular or shaped). Main applications, fixed installations (building cabling, rigid conduits).
• Class 2 Multistranded conductor: Typical construction, multiple strands, compressed or uncompressed. Main applications: Fixed installations requiring some flexibility.
• Class 5 Flexible conductor: Typical structure, numerous thin strands (more than Class 2). Main applications: flexible cables, cords, welding cables.
• Class 6 Extra Flexible Conductor: Typical construction with wires even thinner than Class 5. Main applications are those with extremely flexible wires (e.g., traction cables, portable equipment).

Classes 3 and 4 were present in earlier versions but were removed in the latest version. These classes are no longer used in the current standard.

The EN IEC 60228 standard defines a preferred series of nominal cross-sectional areas. These values ​​are internationally harmonized and used in Europe, Asia, Africa, and much of the world (excluding North America, which still predominantly uses AWG).

This standard specifies the maximum DC resistance values ​​at 20 degrees for both copper and aluminum, for each cross-section and grade. Aluminum values ​​are higher (approximately 1,64–1,69 times higher than copper resistance, depending on the grade).

The main changes made in the latest revision of this standard are as follows:

• Addition of larger cross-sections up to 2500 mm2 (previously up to 2000 mm2).
• Updated resistance values ​​with tighter tolerances.
• Improved definitions and test methods.
• Better compliance with modern high-voltage and renewable energy cabling requirements.

The EN IEC 60228 standard is one of the most important fundamental standards in the field of electrical cables. This standard is considered important for the following reasons:

• It ensures electrical safety: It precisely defines the maximum permissible DC resistance values ​​for each conductor size and class. If the resistance is too high (e.g., due to a small conductor or the use of low-quality metal), the cable will overheat under load, increasing the risk of fire or insulation failure. Compliance with the EN IEC 60228 standard guarantees that a cable will not overheat while carrying its nominal current.
• It guarantees performance and reliability: Designers calculate voltage drop, short-circuit capacity, and current carrying capacity according to the resistance values ​​in this standard. Without this standard, two cables from different manufacturers could have significantly different resistances and exhibit unpredictable system behavior.
• It enables global interchangeability: If a 50 mm² Class 2 copper conductor manufactured in one country conforms to this standard, it will have exactly the same maximum resistance (0,387 Ω/km at 20 degrees). This ensures that cables, connectors, and equipment from any country can work together seamlessly.
• Mandatory reference for almost all cable standards: This standard is normatively referenced (i.e., legally required) by almost every major cable standard worldwide:
• IEC 60502 standard for power cables up to 30 kV.
• IEC 60227 standard for PVC insulated cables.
• IEC 60245 standard rubber insulated cables
• IEC 60811 standard test methods

If a cable claims to meet any of these standards, its conductor must conform to the IEC 60228 standard.

• Legal and regulatory significance: In most countries outside of North America, electrical inspectors, certification bodies, and regulators require proof of compliance with the EN IEC 60228 standard. Non-compliance can lead to the rejection of installations, the cancellation of type approvals, and even criminal liability in the event of an accident.
• It supports the needs of modern energy transition: The latest revision has expanded the dimensions to 2.500 mm2 and narrowed the tolerances to specifically support the following:
• Large offshore wind farms
• High-voltage DC connections
• Gigawatt-scale solar power plants

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its customers, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "EN IEC 60228 Conductors of Insulated Cables" standard.