Overview
ISO 8846:1990 - "Small craft - Electrical devices - Protection against ignition of surrounding flammable gases" specifies test methods and design requirements for electrical equipment used on small craft so that they can be operated in potentially explosive atmospheres without igniting surrounding flammable hydrocarbon gases. The standard targets devices that may produce sparks, arcs or hot surfaces and defines test procedures for both sealed and non-sealed assemblies. It does not require explosion-proof enclosures (as per IEC 79-0) and does not cover hydrogen/air mixtures or external ignition sources such as lightning or static.
Key topics and requirements
- Scope and definitions: Covers propane–air flammable hydrocarbon mixtures between LEL and UEL; defines “ignition-protected device” and “ignition source.”
- External surface temperature test: Devices are placed in a circulating oven at 60°C ±2°C, operated at maximum current for a minimum of 7 hours. Maximum allowable external surface temperature: 200°C. Test voltage is set between 80% and 120% of the nominal system voltage that produces the greatest temperature rise.
- Sealed-device test: Uses a water chamber to detect ingress. Devices are submerged (attitude changed to expose possible leak points) for specified intervals (15 minutes per attitude) and inspected internally for water entry; water ingress requires further non-sealed testing.
- Non-sealed-device test: Performed in a pressure-relief test chamber using propane–air mixtures (ratios near the lower explosive range as specified in the standard), with controlled feeding and an analyser. Devices or mounted spark plugs produce repeated ignition events while chamber ignitability is checked to confirm whether device ignitions can propagate to the surrounding atmosphere.
- Special provisions: Additional procedures for cranking motors, distributors and consideration of intrinsically safe devices are included. Practical test hardware details (vent tubes, spark gaps - 2.5 mm preferred, test assembly layouts) are given.
- Marking: Proven compliant products shall be marked with “ISO 8846” together with the word “MARINE”, marking to be durable.
Applications and users
ISO 8846 is used by:
- Marine equipment designers and manufacturers (switches, relays, cranking motors, generators, distributors, trim motors).
- Test laboratories and certification bodies assessing ignition protection for small craft electrical components.
- Shipyards, small-craft builders and surveyors who must ensure on-board electrical safety in compartments where flammable gases (e.g., fuel vapour) can accumulate.
- Maintenance and retrofit teams specifying replacement parts with proper ignition-protection credentials.
Practical benefits include reduced risk of explosion in engine rooms, fuel locker areas and bilges where electrical equipment operates near flammable hydrocarbon vapours.
Related standards
- IEC 79-0: General requirements for electrical apparatus in explosive gas atmospheres.
- IEC 79-11: Intrinsically safe and associated apparatus.
Keywords: ISO 8846, small craft, ignition protection, electrical devices, flammable gases, marine safety, sealed device test, surface temperature test.
Open preview (PDF)Small craft — Electrical devices — Protection against ignition of surrounding flammable gases
