ISO 8820-4:2016

Overview

ISO 8820-4:2016 - "Road vehicles - Fuse-links - Part 4" specifies requirements for automotive fuse-links with female contacts (type A) and bolt‑in contacts (type B) and their test fixtures. The standard defines rated voltages, current ratings, dimensions, test procedures and performance requirements for fuse-links intended for road vehicles. It applies to fuse‑links rated at 32 V or 58 V, with current ratings ≤ 140 A and a breaking capacity of 1 000 A. ISO 8820‑4 is intended to be used together with ISO 8820‑1 (definitions and general tests) and ISO 8820‑2.

Key technical topics and requirements

• Fuse types and dimensions: Defines physical types A (female contacts) and B (bolt‑in) with dimensional specifications and designation rules to ensure interchangeability and correct fit in fuse‑boxes.
• Rated electrical limits: Applicable voltages (32 V / 58 V), current range up to 140 A, and breaking capacity 1 000 A.
• Test procedures and sequences: Detailed test sequence (sample groups, minimum of 8 samples per group), including electrical, climatic, chemical and mechanical loads as referenced from ISO 8820‑1.
• Electrical tests:
  • Voltage drop measured across specified points; maximum permitted voltage drops are provided in the standard.
  • Transient current cycling, current steps, operating time‑rating and breaking capacity tests to verify protective and time‑current behavior.
  • Connection resistance requirements for test fixtures: ≤ 1.0 mΩ for type A and ≤ 0.35 mΩ for type B to ensure reliable measurements.
  • After breaking capacity test, leakage current limits (≤ 0.5 mA at rated voltage).
• Mechanical and thermal requirements: Terminal strength tests (specified forces per fuse type), temperature rise limits, and rapid temperature‑change tests.
• Test fixtures and cable sizes: Test fixture designs and conductor cross‑section sizes (per Table 3) are specified to standardize comparative testing; conductor material referenced to ISO 6722‑1.
• Operational visibility: Fuse‑links must provide visible evidence of an open fuse element.

Practical applications and users

ISO 8820-4 is essential for:

• Automotive component designers and manufacturers (fuse and fuse‑link producers) - for product design, verification and production testing.
• Vehicle OEMs and electrical systems engineers - to select compliant fuse‑links and ensure system compatibility and safety.
• Test laboratories and certification bodies - to perform standardized tests, type approvals and conformance assessments.
• Suppliers of fuse‑boxes and harnesses - to ensure dimensions, terminal strength and cable interfaces meet vehicle integration requirements.

Related standards

• ISO 8820‑1: Definitions and general test requirements (primary companion document)
• ISO 8820‑2: Other fuse-link types (use in conjunction)
• ISO 6722‑1: Conductor material and cross‑section references for test cables

Keywords: ISO 8820-4, fuse-links, automotive fuses, road vehicles, fuse test fixtures, rated current, breaking capacity, voltage drop, transient current cycling.