Overview
IEC 62420:2008 defines the electrical and mechanical characteristics of concentric lay stranded overhead electrical conductors containing one or more gap(s). The standard covers conductors with one or more self-supporting aluminium or aluminium-alloy layers (annular gaps between layers), and specifies permitted metal combinations, designation rules, tests, inspection, packaging and marking. It applies to both gap-type conductors (aluminium layers able to slide over the core during installation) and self-damping conductors (SDC) (may include multiple gaps to increase vibration damping).
Keywords: IEC 62420, concentric lay stranded overhead conductors, gap(s), annular gap, self-damping conductors, gap-type conductors.
Key topics and requirements
- Scope and materials: Permitted wire types include hard-drawn aluminium (A1), aluminium alloys (A2, A3), thermal-resistant aluminium alloys (AT1–AT4), regular/high/extra-high strength steel (S1–S3 classes), and aluminium-clad steel (20SA–40SA).
- Conductor construction: Defines concentric-lay stranded geometry, lay length/lay ratio, formed wire vs round wire, self-supporting aluminium layers and annular gap definition.
- Designation system: Uses codes such as AxGy/Syz (e.g., 400/66-A1G2/S1A-274) to identify conductive area, core section, envelope type, number of gaps and outside diameter.
- Mechanical and electrical properties: Requirements for linear mass, conductor strength, breaking strength, stress–strain behaviour and creep characteristics.
- Tests and inspection: Classification of type tests and sample tests (stress–strain tests, breaking strength, creep tests per IEC 61395, measurements of diameter, cross-sectional area, lay ratio, surface condition, wire canting). Annexes include test methods, purchaser information and grease mass calculations.
- Packaging & marking: Rules for packaging, marking and random lengths to ensure traceability and compliance.
Applications and users
IEC 62420 is used by:
- Transmission line designers and utilities specifying overhead conductor performance (mechanical strength, damping, installation behaviour).
- Conductor manufacturers and wire suppliers to design and certify gap-type and self-damping concentric-lay conductors.
- Test laboratories performing type and sample tests (stress–strain, creep, breaking strength).
- Procurement and quality assurance teams requiring standardized designation, marking and inspection criteria.
Practical uses include selecting conductor constructions for long-span lines, vibration mitigation (galloping/damping) and installations where sliding aluminium layers reduce handling stress.
Related standards
Relevant referenced IEC standards include:
- IEC 60889 (hard-drawn aluminium wire A1)
- IEC 60104 (aluminium‑magnesium‑silicon alloys A2/A3)
- IEC 62004 (thermal‑resistant aluminium alloys AT1–AT4)
- IEC 60888 (zinc‑coated steel wires S1–S3)
- IEC 61232 (aluminium‑clad steel wires)
- IEC 61395 (creep test procedures for stranded conductors)
Use IEC 62420 when you need standardized guidance on material combinations, conductor designation, mechanical/electrical testing and acceptance criteria for concentric-lay overhead conductors with annular gaps.