ISO 6856:2005

Overview - ISO 6856:2005 for ignition cable assemblies

ISO 6856:2005 specifies test methods and general requirements for unscreened high‑voltage ignition cable assemblies used in road vehicles. The standard establishes environmental, mechanical and electrical tests, preconditioning and reporting conventions to ensure ignition cables and their connectors meet performance, durability and safety expectations in automotive applications.

Key topics and technical requirements

• Scope and conditions
  • Applies to unscreened high‑voltage ignition cable assemblies for road vehicles.
  • General test ambient: (23 ± 5) °C; samples preconditioned at (23 ± 5) °C and 10–75% RH for 24 h.
• Visual examination
  • Check identification, appearance and workmanship; no cracking, significant discoloration, deformation or water ingress allowed.
• Insertion and removal forces
  • Use standardized hardened‑steel gauges for connector types.
  • Insertion force (first insertion): maximum 80 N.
  • Removal force (tenth removal): 20 N minimum and 70 N maximum.
  • Test speeds: 100, 200 or 500 mm/min (to be agreed and recorded).
• Separation force (after heating)
  • Heat exposure per cable class (e.g., 70 °C or 90 °C depending on class) then measure separation: no separation or electrical interruption until at least 10 N above the first measured removal force.
• Electrical insulation tests
  • Two alternative tests: sealing test in 3% NaCl/water (24 h, no spark‑over) or breakdown test in steel balls (1 h, no spark‑over).
  • Voltage classes define peak voltages (examples: sealing test peaks up to 31 kV, breakdown test peaks up to 35 kV, per the tables in the standard).
  • Pulse shape and timing specified (rise time and pulse width at 150 pF).
• Environmental and durability tests
  • Salt spray: 48 h per ISO 9227; no visible corrosion of specimen connections.
  • Thermal shock: 20 cycles between cold and hot chambers (class dependent temperatures).
  • Heat ageing: 168 h at class temperature; no cracking permitted.
• Other considerations
  • Vibration, oil/fuel resistance and additional requirements to be agreed between manufacturer and vehicle OEM; references ISO 16750 series and ISO 3808-2.

Applications and who uses ISO 6856:2005

• Automotive component manufacturers and suppliers of ignition cables, boots and connectors.
• Vehicle OEMs and engine manufacturers for component qualification and supplier audits.
• Independent test laboratories performing mechanical, thermal and electrical endurance tests.
• Quality, R&D and compliance engineers ensuring ignition systems meet safety, durability and electromagnetic performance requirements.

Related standards

• ISO 3808-2 - Cable classes, types and special requirements for high‑tension ignition cables.
• ISO 9227 - Salt spray (corrosion) testing.
• ISO 16750-3 / -5 - Environmental testing for mechanical and chemical loads.

Keywords: ISO 6856:2005, unscreened high‑voltage ignition cable assemblies, test methods, road vehicles, insertion removal forces, electrical insulation tests, thermal shock, salt spray.