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Understanding Amendment 4 (2026) to BS 7671:2018: Key Changes to the 18th Edition IET Wiring Regulations

Understanding Amendment 4 (2026) to BS 7671:2018:
Key Changes to the 18th Edition IET Wiring Regulations

The latest update to the UK’s national standard for electrical installations Amendment 4 (2026) to BS 7671:2018 (18th Edition IET Wiring Regulations), has now been formally signed off by the Institution of Engineering and Technology (IET), in partnership with the British Standards Institution (BSI), and will be published on 15 April 2026.

The new edition, titled BS 7671:2018 + A4:2026 – IET Wiring Regulations (18th Edition), the Orange Book, introduces significant technical changes that will affect design, installation, inspection and certification across multiple sectors, including healthcare, ICT and energy storage.

Implementation & Transition of Amendment 4

Publication date: 15 April 2026
Immediate implementation: The amendment may be applied from the day it’s published
Withdrawal of old version: The previous consolidated version, the familiar Brown Book (BS 7671:2018 + A2:2022 + A3:2024) will be withdrawn six months later (mid-October 2026)

Amendment 4 becomes the recognised UK standard for:
✔ all new low voltage electrical installations
✔ additions and alterations to existing installations
✔ periodic inspection and testing of electrical installations

What’s New in Amendment 4

Amendment 4 brings several important additions and revisions to reflect the evolution of technology and modern electrical practices:

1. New Chapter on Stationary Secondary Batteries
This introduces formal requirements for installations where battery storage systems are used as a permanent part of the electrical supply, recognising the rapid growth of energy storage applications in both residential and commercial environments.

2. Functional Earthing & Equipotential Bonding for ICT Systems
A new section addressing functional earthing requirements for Information and Communication Technology (ICT) equipment, differentiating between protective and functional earthing to support networked systems and structured cabling installations.

3. New Section on Power over Ethernet (PoE)
The regulations now include specific requirements covering Power over Ethernet, which is increasingly used for low voltage power delivery over data cabling. This reflects the proliferation of PoE devices such as access points, VoIP telephones, IoT devices and connected lighting.

4. Major Revision of Section 710 (Medical Locations)
Amendment 4 significantly updates the requirements for electrical installations in medical locations, including additional technical criteria and a schedule for recording the resistance of supplementary protective equipotential bonding conductors, aimed at enhancing safety and continuity of supply.

Why This Matters

This update represents one of the most significant sets of changes since previous amendments and supports:

Adoption of modern electrical technologies and practices
Enhanced safety and performance standards
Clarity in requirements for new systems such as energy storage, ICT and PoE
Alignment with industry expectations and future facing electrical design needs

Given that Amendment 4 is effective from 15 April 2026, industry professionals, including designers, installers, inspectors and testing personnel, will need to update training, documentation and compliance workflows in advance of the transition period ending later in 2026.

Next Steps for Professionals

Ensure access to the BS 7671:2018 + Amendment 4 document as soon as it’s published
Update internal procedures, guidance notes and EICR templates
Attend CPD or update training courses focused on Amendment 4 changes
Communicate the new requirements to clients and staff ahead of the October transition deadline

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Header Column #1
Industries	Principal to all Ex environments, with direct application in hazardous vapour and gas environments.
Entry Qualifications Guidance	Level 3, ECS Gold Card, National Diploma or equivalent. Disipline: Electrotechnical Instrumentation Subject to knowledge, skill and experience candidates may benefit from Ex F+
Entry Knowledge - Expected	Knows the relevant legislative, regulatory, local requirements Understands procedures for safe working practice and systems of work in an industrial setting Can read and interpret relevant engineering drawings, related specifications, quality standards and equipment manuals Understands the hierarchy of responsibilities in relation to reporting and decision-making
Entry Skills - Expected	Practical skills in engineering assembly of a complexity consistent with that of a level 3 craftsperson Can apply safe working practices including safe isolation to meet the requirements of statutory and non-statutory regulations Can safely install, inspect, test, commission, diagnose and correct faults in electrical plant, instrumentation, associated cabling, cabling supports and equipment Can select, gland & terminate industrial type cables to a suitable component and associated cable tray in line with details on the appropriate specification Can interpret manufacturers documentation for correct installation,maintenance and inspection
Job Roles Aspiring to or operating in	Installation or Maintenance Electrician Electrical or Instrument Technician Engineers
Entry Experience Guidance	2 + years' experience operating in a site / industrial environment Installing, inspecting, testing and/or maintaining equipment in an industrial setting
Entry Knowledge - Desirable	Understands the need for and methods of achieving safe working practice in gas and vapour Ex environments Has basic practical, theoretical and technological knowledge and understanding of gas and vapour Ex environments Has a basic understanding of the requirements, materials and equipment considerations, in relation to working in gas and vapour Ex environments
Entry Skills - Desirable	Can select and install a variety of Ex certified cables glands and terminate conductors into equipment Can understand the principles of electrical protection concepts including selection, installation and maintenance Understands intrinsically safe concept of protection and installation including the importance of documentation Can inspect new and existing equipment in accordance with appropriate inspection techniques relevant to the different grades of inspection

Header Column #1

Industries

Principal to all Ex environments, with direct application in hazardous vapour and gas environments.

Entry Qualifications
Guidance

Level 3, ECS Gold Card, National Diploma or equivalent. Disipline:

Electrotechnical
Instrumentation

Subject to knowledge, skill and experience candidates may benefit from Ex F+

Entry Knowledge - Expected

Knows the relevant legislative, regulatory, local requirements
Understands procedures for safe working practice and systems of work in an industrial setting
Can read and interpret relevant engineering drawings, related specifications, quality standards and equipment manuals
Understands the hierarchy of responsibilities in relation to reporting and decision-making

Entry Skills - Expected

Practical skills in engineering assembly of a complexity consistent with that of a level 3 craftsperson
Can apply safe working practices including safe isolation to meet the requirements of statutory and non-statutory regulations
Can safely install, inspect, test, commission, diagnose and correct faults in electrical plant, instrumentation, associated cabling, cabling supports and equipment
Can select, gland & terminate industrial type cables to a suitable component and associated cable tray in line with details on the appropriate specification
Can interpret manufacturers documentation for correct installation,maintenance and inspection

Job Roles
Aspiring to or operating in

Installation or Maintenance Electrician
Electrical or Instrument Technician
Engineers

Entry Experience
Guidance

2 + years' experience operating in a site / industrial environment
Installing, inspecting, testing and/or maintaining equipment in an industrial setting

Entry Knowledge - Desirable

Understands the need for and methods of achieving safe working practice in gas and vapour Ex environments
Has basic practical, theoretical and technological knowledge and understanding of gas and vapour Ex environments
Has a basic understanding of the requirements, materials and equipment considerations, in relation to working in gas and vapour Ex environments

Entry Skills - Desirable

Can select and install a variety of Ex certified cables glands and terminate conductors into equipment
Can understand the principles of electrical protection concepts including selection, installation and maintenance
Understands intrinsically safe concept of protection and installation including the importance of documentation
Can inspect new and existing equipment in accordance with appropriate inspection techniques relevant to the different grades of inspection

Header Column #1
Industries	Principal to all Ex environments, with direct application in hazardous vapour and gas environments.
Entry Qualifications Guidance	Level 3, ECS Gold Card, National Diploma or equivalent. Disipline: Electrotechnical Instrumentation Subject to knowledge, skill and experience candidates may benefit from Ex F+
Entry Knowledge - Expected	Knows the relevant legislative, regulatory, local requirements Understands procedures for safe working practice and systems of work in an industrial setting Can read and interpret relevant engineering drawings, related specifications, quality standards and equipment manuals Understands the hierarchy of responsibilities in relation to reporting and decision-making
Entry Skills - Expected	Practical skills in engineering assembly of a complexity consistent with that of a level 3 craftsperson Can apply safe working practices including safe isolation to meet the requirements of statutory and non-statutory regulations Can safely install, inspect, test, commission, diagnose and correct faults in electrical plant, instrumentation, associated cabling, cabling supports and equipment Can select, gland & terminate industrial type cables to a suitable component and associated cable tray in line with details on the appropriate specification Can interpret manufacturers documentation for correct installation,maintenance and inspection
Job Roles Aspiring to or operating in	Installation or Maintenance Electrician Electrical or Instrument Technician Engineers
Entry Experience Guidance	2 + years' experience operating in a site / industrial environment Installing, inspecting, testing and/or maintaining equipment in an industrial setting
Entry Knowledge - Desirable	Understands the need for and methods of achieving safe working practice in gas and vapour Ex environments Has basic practical, theoretical and technological knowledge and understanding of gas and vapour Ex environments Has a basic understanding of the requirements, materials and equipment considerations, in relation to working in gas and vapour Ex environments
Entry Skills - Desirable	Can select and install a variety of Ex certified cables glands and terminate conductors into equipment Can understand the principles of electrical protection concepts including selection, installation and maintenance Understands intrinsically safe concept of protection and installation including the importance of documentation Can inspect new and existing equipment in accordance with appropriate inspection techniques relevant to the different grades of inspection