Overview
ISO 2635:2003 - "Aircraft - Conductors for general purpose aircraft electrical cables and aerospace applications - Dimensions and characteristics" defines the dimensional, electrical and mechanical requirements for multi‑strand conductors used in general‑purpose aircraft and aerospace electrical cables. It covers stranded conductors with nominal cross‑sectional areas from 0.12 mm² to 107 mm² (WWG28 to WWG0000). The standard excludes conductors for fire‑resistant cables (see ISO 1967) and thermocouple extension cables (see ISO 8056‑1).
Key topics and technical requirements
- Scope and conductor range: Stranded conductors from 0.12 mm² to 107 mm²; lightweight conductor options introduced for new designs (Table 2).
- Materials:
- Nominal ≤ 0.25 mm²: high‑strength copper alloy.
- Nominal > 0.25 mm²: electrotechnical (ETP) copper.
- Size AWG 24 and smaller: high‑strength copper alloy.
- Constructions: Concentric‑lay or rope‑lay stranded conductors; number and diameter of strands specified in Tables 1 and 2.
- Electrical characteristics:
- Maximum resistance and mass per unit length provided per conductor code.
- Resistance corrected to 20 °C using specified formulas:
- Annealed copper: R20 = R(T) / [1 + 0.003931(T − 20)]
- Copper alloy: R20 = R(T) / [1 + 0.003500(T − 20)]
- Mechanical requirements & tests:
- Tensile strength and elongation tested on whole conductor; jaw separation and speed parameters specified (200–300 mm/min for copper; 40–60 mm/min for copper alloy).
- Mass per unit length measurement and resistance limits defined.
- Strand‑plating continuity, adherence and minimum plating thicknesses (silver ≥ 1.0 µm; nickel ≥ 1.25 µm).
- Rules for strand joints (brazed/hard‑soldered; limits on joint frequency and spacing).
- Packaging & labelling: Uniform winding on reels/bobbins/coils, moisture protection and identification labels required.
Applications and who uses it
ISO 2635:2003 is essential for:
- Aerospace cable manufacturers and conductor suppliers specifying conductor dimensions, resistance and mechanical properties.
- Aircraft OEMs, harness designers and electrical engineers standardizing wire sizes (WWG/AWG harmonization) for global programs.
- Maintenance organizations, test labs and regulatory authorities (FAA, EASA/previous JAA, national CAAs) requiring consistent conductor specifications for crimping, terminations and servicing.
- Procurement and specification writers seeking lightweight, internationally compatible conductor options to reduce tooling complexity and maintenance errors.
Related standards
- ISO 1967 - fire‑resisting aircraft cable conductors
- ISO 8056‑1 - thermocouple extension conductors
- NEMA WC 67, BS 3G 231, EN 2083 - historical/related product standards referenced in ISO 2635
Keywords: ISO 2635:2003, aircraft conductors, aerospace conductors, multi‑strand conductors, conductor dimensions, conductor resistance, lightweight conductors, WWG, aircraft electrical cables.
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