Overview
ISO 8846:2025 - "Small craft - Electrical devices - Protection against ignition of surrounding flammable gases" defines test methods and design requirements to ensure electrical equipment on small craft can operate without igniting surrounding flammable gas atmospheres. It replaces ISO 8846:1990 and updates definitions, test procedures and marking requirements. The standard focuses on common marine fuel-air hazards (tested with propane-air mixtures) and excludes devices intended for hydrogen service, dysfunctional components, and ignition mechanisms from external sources (e.g., static, lightning).
Key topics and technical requirements
- Scope and exclusions: Applies to electrical devices on small craft (≤ 24 m hull length) under normal operating conditions; excludes hydrogen-air devices and external ignition sources.
- Definitions: Introduces terms such as flammable hydrocarbon mixture, ignition-protected device, and normal operating conditions (including overloads up to 400 % of rated current and stalled-rotor for motors).
- External surface temperature test (Clause 5):
- Device operated in a circulating oven at 60 °C ± 2 °C.
- Operated until thermal stability (≤ 2 K/h) or minimum 7 h.
- Maximum allowable surface temperature: 200 °C.
- Sealed devices (Clause 6):
- Leak test by submerging device 340–370 mm below water surface; observation for bubbles and internal inspection. Hermetically sealed (metal-to-metal or glass-to-metal) generally accepted without testing.
- Non-sealed devices (Clause 7):
- Uses a controlled propane‑air test atmosphere in a pressure-relief test chamber.
- Chamber mixture: 4.75 % ± 0.25 % propane by volume; device fill ratio adjusted to maximize pressure rise (fallback 4.25 % ± 0.25 % when pressure transducer isn't practical).
- Preparation requirements: minimum 150 mm tubing lengths, tubing ID 1.5–6.5 mm; preferred spark gap 2.5 mm; provisions for small devices (tee fittings, copper vent tubes).
- Special additional requirements for cranking motors, distributors and alternators (Clause 7.5.3 added in this edition).
- Identification (Clause 8): Updated marking requirements to indicate compliance and installation guidance.
Practical applications and users
ISO 8846:2025 is intended for:
- Marine equipment manufacturers designing ignition-protected electrical devices (motors, switches, alternators).
- Product designers and R&D engineers responsible for marine electrical safety and certification.
- Test laboratories and conformity assessment bodies conducting ignition-protection testing.
- Shipyards, installers, marine surveyors and regulators specifying safe onboard electrical equipment and installation practices.
The standard helps ensure safe operation of onboard electrical devices in gasoline-vapor environments and supports regulatory compliance and product acceptance in recreational and small commercial craft.
Related standards
- IEC 60079‑0 (explosion-protected devices) - explosion-protected equipment meets ISO 8846 requirements when installed per its markings.
- ISO 8666 (small craft measurements) - referenced for hull length definition.
Open preview (PDF)Small craft — Electrical devices — Protection against ignition of surrounding flammable gases
