ISO 3808:2002

Overview

ISO 3808:2002 - Road vehicles: unscreened high-voltage ignition cables - defines general specifications, test methods and requirements for the high-voltage ignition leads used in spark‑ignited engines for road vehicles. It sets out cable classes, types, dimensional limits and a comprehensive set of electrical, thermal, mechanical and environmental tests to verify performance and safety.

Key topics and technical requirements

The standard covers:

• Cable classes and types
  • Types are defined by conductor construction and electrical behavior (e.g., Type 1: stranded copper; Type 2: other stranded metal; Type 3A/3B: resistive; Type 4: reactive).
• Dimensions
  • Outside diameter tolerances are specified for common finished cable sizes (5 mm, 7 mm, 8 mm).
• Electrical tests
  • Insulation fault detection (production screening) using high‑voltage AC tests (typical test voltages by diameter: 5 mm = 20 kV r.m.s.; 7 mm and 8 mm = 30 kV r.m.s.).
  • Thirty‑minute salt soak voltage test: 20 kV r.m.s. applied after 4 h in 3 % NaCl solution; no breakdown permitted.
  • Breakdown voltages after soak: minimums specified (e.g., 5 mm ≥ 25 kV r.m.s., 7/8 mm ≥ 35 kV r.m.s.).
  • Capacitance limits: ≤ 250 pF per metre (measured at 1 000 Hz after prescribed conditioning).
  • Corona resistance: maintained at specified voltages (e.g., 5 mm = 15 kV r.m.s.; 7/8 mm = 18 kV r.m.s.) for 8 h without defects.
• Thermal and mechanical tests
  • Thermal overload (class‑dependent oven temperature and 48 h dwell), shrinkage by heat (150 °C, max 2 % length shrinkage), pressure at high temperature (indentation limits), thermal ageing (accelerated life), low‑temperature flexibility (bending under load at specified low temperature), and resistance to flame propagation (controlled Bunsen‑burner exposure; extinction times specified).
• Performance limits
  • Resistance ranges for resistive types (e.g., Type 3A: 3 000–9 000 Ω/m; 3B: 9 000–23 000 Ω/m) and allowable resistance change after certain tests (+50 % / −30 % for resistive types in thermal/shrinkage tests).
• Other tests
  • Mechanical strength, insulation stripping, fluid compatibility (per ISO 1817 referenced), and accelerated life tests.

Practical applications and users

ISO 3808:2002 is used by:

• Automotive OEMs and Tier‑1/2 suppliers for component specification and acceptance testing
• Cable manufacturers for product design, quality control and certification
• Independent test laboratories verifying electrical, thermal and mechanical performance
• Maintenance and procurement engineers who need to ensure replacement leads meet safety and performance criteria

Implementing ISO 3808 helps ensure ignition cables meet consistent safety, durability and electromagnetic performance requirements in spark‑ignited vehicle engines.

Related standards

• ISO 1817:1999 (rubber - effect of liquids) - referenced for fluid compatibility testing
• ISO 4926:1978 - referenced for hydraulic brake system reference fluids (normative references in the document)