Overview
ISO/TR 10134:2020 - "Small craft - Electrical devices - Established practices for the design, construction and installation of lightning-protection systems" - provides established, informative guidance for designing and installing lightning-protection systems on small craft with hull length up to 24 m. The Technical Report describes accepted practices (materials, conductor sizing, mast arrangements, grounding and bonding) and clarifies limitations: a protection system reduces risks but cannot guarantee complete protection from equipment damage or personal injury.
Key topics and technical requirements
- Scope and limitations
- Applies to small craft (≤ 24 m hull length); advisory (informative) guidance rather than prescriptive requirements.
- Explicit statement that full protection from all damage or injury is not implied.
- Materials and corrosion resistance
- Components must be corrosion-resistant; avoid dissimilar-metal junctions or mitigate with compatible platings/special connectors.
- Conductor sizing and construction
- Lightning grounding conductor or mast circuit should have mechanical strength and conductivity at least equal to a 21 mm copper conductor (whole circuit).
- Wire conductors: stranded copper ≥ 13 mm² equivalent conductivity or equal; individual strand diameter ≥ 0.71 mm; insulated copper wires with at least 19 strands; metal ribbon/strip thickness ≥ 1 mm.
- Installation and routing
- Lightning grounding conductors should follow an essentially straight path to the water and not be routed parallel to vessel wiring (minimizes induction and side flashes).
- Conductive joints must preserve conductor conductivity and mechanical support.
- Protection zones and mast height
- For masts ≤ 15 m above water, the protected base radius ≈ mast height (h).
- For masts > 15 m, protection is based on a striking distance (illustrated as a 30 m arc); overlapping zones used for larger craft.
- Alternatives & temporary systems
- Non-conductive masts can be acceptable if fitted with an appropriately straight down conductor and an air terminal; radio antennas or outriggers may serve if they meet grounding practices.
- Temporary metal masts connected to a submerged lightning ground plate (≥ 0.1 m²) may be used when needed.
- Bonding and interconnection
- Metallic masses within ~2 m of grounding conductors should be interconnected by a lightning bonding conductor (equivalent to ~13 mm² copper) or grounded to the ground plate to prevent side flashes.
- Documentation
- Annex A recommends owner’s manual content describing lightning-protection features and precautions.
Applications - who uses this standard
- Yacht and small craft designers and naval architects
- Marine electrical installers and shipyards
- Surveyors, classification societies, marinas and safety officers
- Boat owners and maintenance personnel (for safe operation and owner manuals)
ISO/TR 10134:2020 is practical guidance for implementing marine lightning protection on recreational and small commercial vessels.
Related standards
- IEC 60092-352 (for additional recommendations on conductor sizing and grounding practice)
- This Technical Report replaces ISO 10134:2003 and aligns with ISO/IEC standardization guidance.
Keywords: ISO/TR 10134:2020, small craft lightning protection, lightning-protective mast, lightning grounding conductor, lightning ground plate, marine lightning protection, lightning bonding conductor, corrosion resistance, protection zone.