ISO 10924-2:2025

Overview

ISO 10924-2:2025, Road vehicles - Circuit breakers - Part 2: Guidance for users, is an international standard developed by ISO. This document provides essential guidance for the selection and application of automotive circuit breakers in road vehicles. It helps users evaluate key parameters in order to select the most suitable circuit breaker for specific electrical and electronic applications within automotive systems.

Choosing the right automotive circuit breaker ensures reliable circuit protection, prevents premature equipment failure, and maintains the safety and integrity of vehicle electrical systems. This standard is designed for use by engineers, designers, manufacturers, and maintenance professionals in the automotive industry.

Key Topics

ISO 10924-2:2025 covers a comprehensive range of factors affecting the choice and efficient use of circuit breakers in road vehicles:

• Selection Criteria: Outlines important parameters such as continuous current, operating time, overload protection, and environmental conditions for proper circuit breaker selection.
• Electrical Parameters: Discusses circuit breaker nominal voltage, rated current, and continuous current relevant to specific automotive applications.
• Cable and Conductor Considerations: Examines the impact of cable cross-section, insulation, and installation conditions on circuit breaker performance.
• Temperature Effects: Explains how ambient temperature and temperature rise affect current ratings and circuit breaker operations.
• Contact Resistance: Describes the influence of connection resistance and the importance of proper circuit breaker terminals and cable specifications.
• Cable Protection: Provides guidance on ensuring that circuit breakers trip in advance of reaching maximum cable temperatures, preventing cable overheating.
• Selectivity: Covers hierarchical circuit breaker coordination to prevent cascading circuit disconnections.
• Replacement and Safety: Recommends best practices for safe replacement of circuit breakers.
• Inrush and Overcurrent: Advises on considering the inrush withstand characteristics of circuit breakers when selecting for loads with high startup currents.
• Environmental Compatibility: Addresses the need for materials suitable for vehicle environments, avoiding hazardous metals, and proper terminal plating to prevent corrosion.

Applications

The practical guidance in ISO 10924-2:2025 is applicable to a wide spectrum of automotive electrical system designs and maintenance procedures:

• Vehicle Electrical System Design: Supports automotive engineers during the initial design phase of electrical systems, aiding in matching circuit breakers to specific loads and cable configurations.
• Maintenance and Repair: Assists workshop technicians and maintenance personnel in identifying compatible replacement circuit breakers and conducting safe replacements.
• Manufacturing: Helps OEMs and automotive component manufacturers ensure correct specification and installation of circuit breakers in vehicles, enhancing product safety and reliability.
• Aftermarket Installations: Provides valuable reference for installing additional electrical accessories or custom equipment, ensuring proper circuit protection is maintained.
• Circuit Diagnostics: Facilitates troubleshooting by explaining factors influencing breaker operation, such as temperature, voltage peaks, and conductor specifications.

Related Standards

For a complete approach to automotive circuit protection, ISO 10924-2:2025 references and aligns with other international standards, including:

• ISO 10924-1: Road vehicles - Circuit breakers - Part 1: Definitions and general test requirements (defining basic automotive circuit breaker parameters and tests)
• ISO 8820-1: Road vehicles - Fuse-links - Part 1: Definitions and general test requirements (for comparable fuse standards and terminology)
• ISO 10924-3, -4, -5: Additional parts in the ISO 10924 series addressing specific types and requirements for automotive circuit breakers

These related standards help ensure harmonization, interoperability, and a unified approach to automotive electrical component selection and testing.

Keywords: ISO 10924-2:2025, automotive circuit breakers, road vehicles, circuit protection, cable selection, electrical system safety, circuit breaker application, automotive standards, vehicle maintenance, circuit breaker selection guidance