ISO 10924-4:2025

Road vehicles - Circuit breakers - Part 4: Medium circuit breakers with tabs (Blade type), Form CB15

This document specifies medium circuit breakers with tabs (blade type), Form CB15, for use in road vehicles. It establishes, for this circuit breaker form, the rated current, test procedures, performance requirements and dimensions. This document is intended to be used in conjunction with ISO 10924-1 and ISO 10924-2. The numbering of its clauses corresponds to that of ISO 10924-1, whose requirements are applicable, except where modified by requirements particular to this document. This document is applicable to circuit breakers with a rated voltage of 14 V (DC) or 28 V (DC) or 58 V (DC), a current rating of no greater than 40 A and a breaking capacity of 2 000 A, intended for use in road vehicles with a nominal voltage of 12 V (DC) or 24 V (DC) or 48 V (DC). The circuit breakers are different in dimensions and functions, such as electric reset, automatic reset, manual reset and switchable. NOTE This type of circuit breaker is intended to be used in applications such as medium fuse-links in accordance with ISO 8820-3. While the tab dimensions and current ratings can be the same, there can be differences in performance which the user of these products is advised to consider.

Véhicules routiers — Coupe-circuits — Partie 4: Coupe-circuits moyens à languettes (de type lame), forme CB15

General Information

• Status: Published
• Publication Date: 31-Mar-2025
• ICS: 43.040.10 - Electrical and electronic equipment
• Technical Committee: ISO/TC 22/SC 32 - Electrical and electronic components and general system aspects
• Drafting Committee: ISO/TC 22/SC 32 - Electrical and electronic components and general system aspects
• Current Stage: 6060 - International Standard published
• Start Date: 01-Apr-2025
• Due Date: 24-Nov-2024
• Completion Date: 31-Mar-2025

Relations

• Revises: ISO 10924-4:2015 - Road vehicles - Circuit breakers - Part 4: Medium circuit breakers with tabs (Blade type), Form CB15
• Effective Date: 06-Jun-2022

Overview

ISO 10924-4:2025 - Road vehicles - Circuit breakers - Part 4: Medium circuit breakers with tabs (Blade type), Form CB15 - defines the rated currents, dimensions, test procedures and performance requirements for blade-type medium circuit breakers used in road vehicles. It applies to circuit breakers rated at 14 V, 28 V or 58 V (DC) for use in vehicles with nominal voltages 12 V, 24 V or 48 V (DC), with current ratings up to 40 A and a breaking capacity of 2 000 A. This part is intended to be used alongside ISO 10924-1 and ISO 10924-2.

Key topics and technical requirements

• Form and scope: Blade/tab style circuit breakers, Form CB15; available in electric reset, automatic reset, manual reset and switchable variants.
• Electrical ratings: Rated voltages (14/28/58 V DC), current ≤ 40 A, breaking capacity 2 000 A.
• Test procedures: Comprehensive test sequence plan (see Table 2) covering:
  • Voltage drop (fast and standard versions)
  • Operating time-rating and current steps
  • Absolute breaking capacity and breaking capacity tests
  • Endurance, dielectric strength and strength of terminals
  • Maximum housing temperature, no-current trip and reset temperature
  • Environmental (climatic, chemical, vibration, shock, free-fall) tests
• Test fixtures and conditions: Electrical tests use a Type C fixture per ISO 8820-3 with a connection resistance ≤ 0.8 mΩ. Environmental temperature ranges are guided by ISO 16750-4.
• Marking and colour coding: Standard colour codes for rated currents (e.g., 5 A - tan/light brown, 10 A - red, 20 A - yellow, 40 A - orange) to aid identification.
• Dimensions & categories: Clause 6 defines dimensional categories (A–K) and designation examples to ensure mechanical interchangeability.

Practical applications and users

ISO 10924-4 is essential for:

• Automotive OEMs and ECU/electrical system designers specifying circuit protection
• Tier‑1 suppliers and component manufacturers developing blade-type circuit breakers
• Test laboratories performing compliance and type-testing to ISO requirements
• Procurement and conformity managers verifying component compatibility and safety
• Designers replacing or comparing medium fuse-links (ISO 8820-3) and circuit breakers for accessory, lighting, infotainment and power distribution circuits

Note: while tab dimensions and current ratings can match ISO 8820-3 fuse-links, performance can differ - users should review breaking and endurance characteristics.

Related standards

• ISO 10924-1 - Definitions and general test requirements
• ISO 10924-2 - Guidance for users
• ISO 8820-3 - Fuse-links with tabs (blade type) Type C (medium)
• ISO 16750-4 - Climatic loads for vehicle electrical/electronic equipment
• ISO 6722-1 - Single-core cables (referenced for test cable sizes)

Keywords: ISO 10924-4, circuit breakers, road vehicles, medium circuit breakers, blade type, Form CB15, automotive circuit protection, breaking capacity, test procedures, electrical reset.

Standards Content (Sample)

International
Standard
ISO 10924-4
Third edition
Road vehicles — Circuit breakers —
2025-03
Part 4:
Medium circuit breakers with tabs
(Blade type), Form CB15
Véhicules routiers — Coupe-circuits —
Partie 4: Coupe-circuits moyens à languettes (de type lame),
forme CB15
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Marking, labelling and colour coding . 2
5 Tests and requirements . 2
5.1 General .2
5.1.1 General test conditions .2
5.1.2 -Test sequence plan .3
5.1.3 Test cable sizes .3
5.2 Voltage drop .4
5.2.1 Purpose .4
5.2.2 Tests .4
5.2.3 Requirements .4
5.3 Maximum housing temperature .4
5.4 Environmental conditions .5
5.5 Operating time-rating .5
5.5.1 Purpose .5
5.5.2 Tests .5
5.5.3 Requirements .5
5.6 Current steps .5
5.7 No current trip and reset temperature .5
5.8 Absolute breaking capacity .5
5.8.1 Purpose .5
5.8.2 Tests .6
5.8.3 Requirements .6
5.9 Breaking capacity .6
5.9.1 Purpose .6
5.9.2 Tests .6
5.9.3 Requirements .6
5.10 Strength of terminals.6
5.11 Endurance .6
5.11.1 Purpose .6
5.11.2 Tests .6
5.11.3 Requirements .7
5.12 Dielectric strength .7
5.12.1 Purpose .7
5.12.2 Tests .7
5.12.3 Requirement .7
6 Dimensions and designation example . 8
6.1 Dimensions .8
6.1.1 Category A .8
6.1.2 Category B .9
6.1.3 Category C .9
6.1.4 Category D .10
6.1.5 Category E .10
6.1.6 Categories F and G .11
6.1.7 Category H .11
6.1.8 Category J . 12
6.1.9 Category K . 12
6.2 Designation example . 13

iii
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of
(a) patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 32,
Electrical and electronic components and general system aspects.
This third edition cancels and replaces the second edition (ISO 10924-4:2015), which has been technically
revised.
The main changes are as follows:
— in Table 2 the test sequence plans were modified for tests No 1, 7, 14, 15 and 19;
— the voltage test at 5.2.2 has been split into fast and standard versions of the circuit breaker;
— the tests for dielectric strength in 5.12.1 and the requirements in 5.12.2 have been clarified.
A list of all parts in the ISO 10924 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

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