ISO 20934:2019

Overview - ISO 20934:2019 and fuse-links for 48V networks

ISO 20934:2019 specifies fuse-links with axial terminals (strip fuse-links) - Types SF36‑70V, SF51‑70V and SF56‑70V - intended for use in road-vehicle electrical systems with a nominal voltage of 48 V DC. The standard defines rated voltage (70 V DC), rated currents from 30 A to 500 A, a breaking capacity of 2 500 A, plus the required test procedures, performance limits and dimensional requirements for these fuse types. It is intended to be used together with ISO 8820‑1 and ISO 8820‑2.

Key topics and technical requirements

• Rated parameters: 70 V DC rated voltage; rated currents 30 A–500 A; breaking capacity 2 500 A for automotive 48V systems.
• Performance and testing: specifies tests and pass/fail criteria including:
  • Voltage drop measurements
  • Current cycling and current-step tests
  • Operating time rating (fuse melting/clearing characteristics)
  • Breaking capacity verification
  • Overload, cold-resistance and insulation resistance tests
  • Mechanical stability, shock and vibration tests
  • Environmental tests (climatic, chemical and temperature shock)
• Design and marking: requirements for marking, labelling and colour coding (fuse-links shall be additionally marked with U “70 V”; a colour-code table is provided for rated-current identification).
• Dimensions and mounting: dimensional requirements, including bolt‑down and clinchable variants and test-fixture specifications, plus examples of designation.

Practical applications

• 48V vehicle electrical protection: selection and qualification of inline fuses for mild‑hybrid and 48V power-distribution architectures.
• Component design and validation: use by fuse manufacturers to design axial strip fuses that meet automotive durability, electrical and environmental requirements.
• System safety and compliance: integration by OEMs and Tier‑1 suppliers to ensure circuit protection meets standardized breaking capacity, operating time and environmental resilience.
• Test and certification: benchmark for laboratories performing electrical, climatic and mechanical testing of automotive fuse-links.

Who should use this standard

• Automotive OEM engineers and electrical system designers
• Fuse and component manufacturers (R&D and quality teams)
• Test houses and certification bodies
• Procurement and compliance teams specifying fuse performance for 48V networks

Related standards

• ISO 8820‑1 and ISO 8820‑2 (fuse-links definitions and general requirements)
• ISO 6722‑1 (vehicle single-core cables)
• ISO 16750‑3, ISO 16750‑5 (environmental testing for electrical/electronic equipment)
• IEC 60068‑2‑14 (temperature change tests)

ISO 20934:2019 provides a focused, test-driven specification for axial fuse‑links used in modern 48V automotive networks, helping manufacturers and vehicle makers ensure reliable circuit protection and regulatory conformance.