Overview
ISO 10924-1:2025 - Road vehicles - Circuit breakers - Part 1: Definitions and general test requirements is an international standard developed by ISO that defines terminology and specifies general test requirements for circuit breakers used in road vehicles. This standard applies to circuit breakers operating at nominal voltages of 12 V (DC), 24 V (DC), 48 V (DC), and 450 V (DC). As a foundational document, it serves as the basis for further, more detailed parts in the ISO 10924 series, providing consistency and harmonization in electrical protection within the automotive sector.
Key Topics
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Definitions of Circuit Breakers and Components
ISO 10924-1:2025 clearly defines terms related to circuit breakers, including their types (automatic reset, manual reset, electrically reset, and switchable), core functions (trip mechanics, reset mechanisms), and component parts (housing, terminal, time-delayed element).
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General Test Requirements
The standard outlines general methodologies for testing circuit breakers, ensuring they meet robust performance and safety criteria:
- Ambient test conditions (temperature, humidity)
- Test fixture configurations
- Measurement tolerances for critical variables including current, voltage, and resistance
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Marking and Identification
Circuit breakers must display critical markings such as rated current, supply voltage, manufacturer information, and part numbers, along with visible and permanent color coding.
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Performance and Environmental Testing
Extensive test requirements ensure that circuit breakers function reliably under various stresses found in vehicle environments:
- Voltage drop tests: Measure efficiency and energy consumption
- Thermal tests: Assess maximum housing temperature and operational limits
- Mechanical, climatic, and chemical load tests: Evaluate performance under real-world operating conditions as prescribed by referenced standards
- Overcurrent protection: Tests evaluating operating time, trip and reset characteristics, and breaking capacity
Applications
The practical applications of ISO 10924-1:2025 center on its use in the automotive industry, supporting both manufacturers and users of circuit breakers in road vehicles:
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Automotive Manufacturers
Build reliable electrical systems for passenger cars, commercial vehicles, buses, and trucks that meet internationally recognized safety and quality requirements for overcurrent protection.
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Component Suppliers
Develop and test circuit breakers to consistent benchmarks, ensuring global market compatibility and regulatory compliance.
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Testing Laboratories
Employ standardized test procedures to validate the safety and performance of circuit breakers at varying nominal voltages (12 V to 450 V DC).
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Regulatory Authorities and Inspectors
Reference the standard for conformity assessments and technical inspections, thereby promoting harmonized safety standards across regions.
Related Standards
For comprehensive electrical safety and system design in vehicles, ISO 10924-1:2025 should be used alongside the following related standards:
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ISO 10924-2 – Guidance for users
Provides detailed instructions for selecting and applying circuit breakers defined in Part 1.
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ISO 10924-3 – Miniature circuit breakers with tabs (Blade type), Form CB11
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ISO 10924-4 – Medium circuit breakers with tabs (Blade type), Form CB15
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ISO 10924-5 – Circuit breakers with bolt for rated voltages up to 450 V
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ISO 8820 Series – Fuse-links requirements
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ISO 16750 Series – Environmental testing for electrical and electronic equipment in road vehicles
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IEC 60068-2-70 – Abrasion testing of markings and labels
ISO 10924-1:2025 plays a vital role in promoting the safety, interoperability, and reliability of automotive electrical systems by standardizing definitions, marking requirements, and general testing protocols for circuit breakers across global markets. For stakeholders involved in automotive electrical protection, aligning with this standard ensures product quality, safety, and regulatory compliance.