ISO 10924-4:2015

Overview

ISO 10924-4:2015 specifies medium circuit breakers with tabs (blade type), Form CB15, for use in road vehicles. It defines the rated current, dimensions, test procedures and performance requirements for CB15 blade-type automotive circuit breakers. This part is intended to be used alongside ISO 10924‑1 (definitions and general test requirements) and ISO 10924‑2 (user’s guide).

Key parameters covered:

• Rated voltages: 14 V d.c., 28 V d.c., 58 V d.c.
• Intended nominal vehicle systems: 12 V, 24 V, 48 V d.c.
• Maximum current rating: ≤ 40 A
• Breaking capacity: 2 000 A

Key topics and technical requirements

ISO 10924-4 defines test methods and performance criteria specific to CB15 blade circuit breakers. Major technical topics include:

• Test sequence plan and conditions - tests follow sequences aligned with ISO 10924-1; electrical test fixture Type C per ISO 8820‑3 with maximum connection resistance 0.8 mΩ.
• Environmental range - ambient operating temperatures −40 °C to 85 °C (Code G, ISO 16750‑4).
• Electrical performance tests:
  • Voltage drop measurement across tabs at 0.7 × rated current.
  • Operating time-rating and multiple current-step tests (various multiples of rated current).
  • Absolute breaking capacity and breaking capacity tests up to the specified 2 000 A.
  • No-current trip / reset temperatures, dielectric strength and endurance.
• Mechanical tests - terminal strength, vibration, shock and free-fall as required.
• Dimensions, marking and colour coding - standard tab dimensions and colour code per rated current to aid identification (examples: 5 A tan, 10 A red, 20 A yellow, 40 A orange).
• Test cable sizes - specified per rated current (see standard Table 3), using conductor materials per ISO 6722‑1.

Note: CB15 breakers can be electrically reset, automatic reset, manual reset or switchable. Performance can differ from blade-type fuse-links (ISO 8820‑3) even when tab dimensions and current ratings match.

Practical applications and users

ISO 10924-4 is essential for:

• Automotive electrical and electronic component manufacturers (design, production, interchangeability)
• OEMs and vehicle system engineers (component selection and system protection design)
• Test laboratories and certification bodies (type testing and compliance verification)
• Aftermarket and fleet maintenance teams (replacement and compatibility assessment)

Typical uses: medium-current circuit protection in passenger cars, commercial vehicles, off-highway vehicles and other road vehicles where standardized blade-type medium circuit breakers are required.

Related standards

• ISO 10924-1: Definitions and general test requirements
• ISO 10924-2: User’s guide
• ISO 10924-3: Miniature circuit breakers, Form CB11
• ISO 8820-3: Fuse links with tabs (Blade type)
• ISO 6722-1: Road vehicle cables (conductor specs)
• ISO 16750-4: Environmental/climatic testing

Keywords: ISO 10924-4:2015, medium circuit breakers, Form CB15, blade type, automotive circuit protection, rated current, breaking capacity, voltage drop, automotive standards.