IEC 60502-1:2021, titled 'Electric cables with extruded insulation and their accessories for rated voltages from 1 kV (Um = 1.2 kV) up to 30 kV (Um = 36 kV) - Part 1: Cables for rated voltages from 1 kV (Um = 1.2 kV) up to 3 kV (Um = 3.6 kV)', published by the International Electrotechnical Commission (IEC), is the third edition of this series of standards, replacing the second edition from 2004 and its 2009 amendment. As an authoritative technical specification for the manufacturing, inspection, and application of global medium and low voltage power cables, its revisions reflect significant developments in cable material technology, testing methods, and application requirements over the past decade.
The core technical changes in this revision include a comprehensive update to the IEC 60811 series of test method standards, with specific consideration given to mechanical testing requirements for halogen-free low-smoke sheath material ST8; clarification of usage specifications for sheath material types; the first inclusion of cable applications in DC systems within the standard scope; and research into previously marked 'to be considered' items, providing appropriate solutions or temporary removal. These changes reflect the standardization body's response to new technology applications and the reinforcement of safety requirements.
This standard specifies the structure, dimensions, and test requirements for extruded solid insulated power cables for fixed installation with rated AC voltages of 1 kV (Um = 1.2 kV) and 3 kV (Um = 3.6 kV), applicable to fixed installation sites such as distribution networks or industrial installations. Notably, an important extension in the 2021 edition is the clarification that cables with a rated AC voltage of 1 kV designed and tested according to this standard may also be used for DC distribution systems upon manufacturer declaration.
| System Type | Rated Voltage | Maximum Voltage | Application Conditions |
|---|---|---|---|
| AC System | U0/U = 1kV/1.2kV | Um = 1.2kV | Standard Scope of Application |
| AC System | U0/U = 3kV/3.6kV | Um = 3.6kV | Standard Scope of Application |
| DC System (Line-to-Ground) | ≤750 V DC | 900 V DC | Manufacturer Declaration, Compliant with Local Installation Regulations |
| DC System (Line-to-Line) | ≤1500 V DC | 1800 V DC | Manufacturer Declaration, Compliant with Local Installation Regulations |
This extension reflects the rapid development of DC distribution systems in fields such as renewable energy integration and data center power supply. The standard also states that conductor identification for DC systems shall comply with local installation regulations; IEC 60445 provides recommended colors for DC system line conductors, but local regulations may already have specific requirements.
This standard also includes cables with flame retardant, low smoke, and halogen-free characteristics, which exhibit reduced flame spread, low smoke emission, and no halogen gas emission under fire conditions. However, the standard does not apply to cables for special installation and service conditions, such as overhead network cables, mining industrial cables, nuclear power plant cables, submarine cables, shipboard cables, or cables directly connected to photovoltaic systems.
IEC 60502-1:2021 systematically classifies cable insulation and sheath materials and specifies corresponding maximum conductor operating temperatures. Insulation materials mainly include polyvinyl chloride (PVC/A), cross-linked polyethylene (XLPE), ethylene propylene rubber (EPR), and hard ethylene propylene rubber (HEPR). Sheath materials include polyvinyl chloride (PVC), thermoplastic polyethylene (PE), and halogen-free materials, among others.
| Insulation Material Type | Designation | Max Conductor Temperature | Short-circuit Temperature | Main Characteristics |
|---|---|---|---|---|
| Polyvinyl Chloride | PVC/A | 70°C | 160°C | Low cost, good flame retardancy, oil resistant |
| Cross-linked Polyethylene | XLPE | 90°C | 250°C | Excellent electrical performance, good heat resistance |
| Ethylene Propylene Rubber | EPR | 90°C | 250°C | Good flexibility, moisture resistant |
| Hard Ethylene Propylene Rubber | HEPR | 90°C | 250°C | High hardness, good mechanical strength |
Insulation thickness is a key parameter in cable design; the standard specifies nominal thickness requirements for different materials and voltage levels. For 1 kV cables, the nominal thickness of PVC/A insulation ranges from 1.0 mm to 1.8 mm depending on conductor cross-sectional area; XLPE insulation ranges from 0.7 mm to 1.4 mm; and EPR and HEPR insulation ranges from 1.0 mm to 1.8 mm. Insulation thickness for 3 kV cables increases accordingly to meet higher electrical strength requirements.
In modern data center power distribution systems, cable current-carrying capacity, heat dissipation performance, and fire safety are critical. According to IEC 60502-1:2021, for applications requiring high current-carrying capacity and excellent heat dissipation, it is recommended to select XLPE insulated cables. Their allowable maximum conductor temperature of 90°C is 20°C higher than that of PVC/A insulation, significantly improving current-carrying capacity. Additionally, considering the high fire safety requirements of data centers, sheath materials with flame retardant, low smoke, and halogen-free characteristics should be selected, such as the ST8 material type defined in the standard. This material produces low smoke density during combustion and does not release corrosive halogen gases, facilitating personnel evacuation and equipment protection.
Chapters 7 to 13 of the standard detail requirements for the assembly, inner sheath, filling, metallic layers, metallic screens, concentric conductors, metallic sheaths, metallic armoring, and outer sheaths of multi-core cables. These structural elements collectively form the cable's mechanical protection and electromagnetic shielding system.
Appendix A provides a virtual calculation method for determining protective layer dimensions, an important tool for cable design engineers. This method systematically calculates the dimensions of each cable layer using the concept of virtual diameter, ensuring the rationality and standardization of the cable structure. The calculation involves parameters such as conductor virtual diameter, cabling factor, diameter increase for concentric conductors and metallic screens, and diameter increase for additional bedding.
| Structural Element | Main Function | Material Type | Key Parameters |
|---|---|---|---|
| Conductor | Current Transmission | Copper, Aluminum | Cross-sectional Area, Resistivity |
| Insulation | Electrical Insulation | PVC/A, XLPE, EPR, HEPR | Thickness, Dielectric Strength |
| Metallic Screen | Electric Field Control, Fault Current Path | Copper Tape, Copper Wire | Cross-sectional Area, Coverage |
| Metallic Armor | Mechanical Protection | Steel Wire, Steel Tape | Diameter/Thickness, Number of Layers |
| Outer Sheath | Environmental Protection | PVC, PE, Halogen-free Materials | Thickness, Environmental Stress Crack Resistance |
Metallic armor is a key component of cable mechanical protection. The standard specifies nominal diameters for round wire armor and nominal thicknesses for tape armor. For wire armor, the diameter ranges from 1.25 mm to 4.00 mm; for tape armor, the thickness is typically 0.5 mm or 0.8 mm. The choice of armor depends on the cable's installation environment and expected mechanical stress.
IEC 60502-1:2021 establishes a complete cable testing system, including routine tests, sample tests, type tests (electrical and non-electrical), and electrical tests after installation. This system ensures quality control throughout the entire process from production to installation and use.
Routine tests are tests performed on every manufactured length of cable, mainly including conductor resistance measurement and voltage tests. For 1 kV cables, the routine test voltage is 3.5 kV (AC) or 8.4 kV (DC), lasting 5 minutes; for 3 kV cables, the test voltage is 6.5 kV (AC) or 15.6 kV (DC). These tests aim to detect accidental defects during the manufacturing process.
Sample tests are tests performed on samples drawn from a batch of cables to verify that the cable design and manufacturing comply with standard requirements. Table 12 of the standard specifies the required sample quantities for different test items, including dimensional checks, mechanical property tests, and thermal aging tests.
Type tests are the most comprehensive tests to verify whether the cable design complies with standard requirements, divided into electrical type tests and non-electrical type tests. Electrical type tests include tanδ measurement, thermal cycle voltage tests, and impulse voltage tests, verifying the cable's long-term electrical performance. Non-electrical type tests, detailed in Tables 14 to 23, specify requirements for various mechanical properties, thermal aging performance, and environmental stress crack resistance of different insulation and sheath materials.
Taking XLPE insulation material as an example, its non-electrical type test requirements include: mechanical properties before aging (tensile strength ≥ 12.5 MPa, elongation at break ≥ 200%); mechanical properties after air oven aging (tensile strength change rate ≤ ±25%, elongation at break change rate ≤ ±25%); heat elongation test (elongation under load ≤ 175%, permanent deformation after cooling ≤ 15%); as well as water absorption tests and shrinkage tests. These rigorous tests ensure the reliability of cable materials during long-term operation.
Electrical tests after installation are performed after cable laying and installation is completed to verify that the installation process has not damaged the cable's insulation system. Chapter 19 of the standard details test voltages, durations, and acceptance criteria, providing a clear technical basis for on-site acceptance.
Based on the technical requirements of IEC 60502-1:2021, the following key points should be noted in practical engineering applications:
1. Cable Selection Principles: Select cable types comprehensively based on installation environment, load characteristics, safety requirements, and other factors. For indoor installations and densely populated areas, prioritize halogen-free low-smoke flame retardant cables; for high-temperature environments or applications requiring high current-carrying capacity, select XLPE or EPR insulated cables; for direct burial or situations involving significant mechanical stress, select cables with metallic armor.
2. DC Application Considerations: When AC cables manufactured according to this standard are used in DC systems, a clear declaration from the manufacturer must be obtained, and the DC system voltage must not exceed the limits specified in the standard. Additionally, attention should be paid to the differences in electric field distribution between DC and AC, particularly at cable terminations and joints.
3. Testing Verification Strategy: Establish a complete cable quality verification system, including Factory Acceptance Tests (FAT), Site Acceptance Tests (SAT), and regular preventive tests. Pay special attention to updated test requirements in the new standard, such as mechanical testing requirements for halogen-free low-smoke sheath material ST8.
4. Installation and Maintenance Specifications: Strictly follow the cable manufacturer's installation instructions for laying, bending, fixing, and connecting. Pay attention to minimum bending radius requirements to avoid mechanical damage during installation. Establish a cable operation monitoring and maintenance plan to regularly check cable temperature, load, and environmental conditions.
| Application Scenario | Recommended Cable Type | Key Considerations | Special Test Requirements |
|---|---|---|---|
| Commercial Building Power Distribution | Halogen-free Low-smoke Flame Retardant Cable | Fire Safety, Smoke Toxicity | IEC 60332-3-24 Bunched Flame Test |
| Industrial Plant Power | XLPE Insulated Steel Tape Armored Cable | Mechanical Protection, Heat Resistance | Impulse Voltage Test, Thermal Cycle Test |
| Data Center Power Supply | Low-smoke Halogen-free Flame Retardant Cable | Current Capacity, Heat Dissipation, Fire Safety | Smoke Density Test (IEC 61034-2) |
| DC Microgrid | DC-Applicable Cable with Manufacturer Declaration | DC Voltage Level, Polarity | DC Withstand Voltage Test, Polarity Reversal Test |
The publication and implementation of IEC 60502-1:2021 provide the latest international technical specifications for the design, manufacturing, testing, and application of medium voltage power cables. As power systems move towards intelligence and low carbonization, cable technology continues to advance. The extensions for DC applications, specifications for halogen-free low-smoke materials, and updates to testing methods in this standard all reflect the standardization body's response to technological development trends and its continuous pursuit of safety and reliability. Engineering and technical personnel should deeply understand the technical requirements of the standard, combine them with actual application conditions, and reasonably select and use cable products to ensure the safe and reliable operation of power systems.
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Update:
Sat, 11 Jul 2026 19:58:26 +0000