Amendment 4 to BS 7671:2018 represents the most significant update to the IET Wiring Regulations since the 18th Edition launched in 2018. This amendment will bring the UK's electrical installation standards in line with evolving European harmonised standards and address rapidly emerging technologies in the electrical sector.

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Timeline of Events

31 July 2024 – IET and BSI announced Amendment 3:2024 and confirmed the upcoming Draft for Public Consultation (DPC) for Amendment 4

7 August 2024 – Draft for Public Consultation (DPC) for Amendment 4:2026 officially opened, divided into four sections for ease of review

3 November 2024 – Public consultation period closed after 12 weeks of industry feedback

2026 – Amendment 4 expected to be published (specific date to be confirmed)

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Current Compliance Requirements

Until Amendment 4 is published, electrical installers must work to:

• BS 7671:2018+A2:2022 (the 'brown book' – Amendment 2)

• Corrigendum (May 2023) (free PDF download)

• Amendment 3:2024 (free PDF 'bolt-on' download)

These will remain valid until Amendment 4 comes into effect in 2026.

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Expected Changes in Amendment 4

The amendment has been developed in response to rapid technological developments and will incorporate changes to harmonised standards at European level, which the UK must adopt within specified timeframes.

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New Sections and Chapters

• Section 545 – Functional earthing and functional-equipotential-bonding for information and communication technology (ICT) equipment and systems, including broadcast, communication technology, and computer network systems

• Chapter 57 – Stationary secondary battery installations (addressing the growth in battery storage systems)

• Section 716 – Distribution of extra-low voltage DC power using balanced information technology cables and accessories primarily designed for data transmission

• Low Voltage Generating Sets – Detailed requirements addressing the increase in on-site power generation

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Key Technical Updates

• Power Over Ethernet (PoE) – New requirements addressing the growing use of PoE technology in modern installations

• Energy Efficiency – Requirements focused on improving energy efficiency in electrical installations

• TN-S Earthing Arrangements – Updates to earthing system requirements

• Ferromagnetic Enclosures – Changes to requirements for bringing conductors into ferromagnetic enclosures, including clarification on current ratings and temperature-rise testing requirements

• Arc Fault Detection Devices (AFDDs) – New requirements for AFDDs on electric vehicle charging installations (EVCIs)

• RCD Requirements – Updates to RCD protection for outdoor lighting installations

• Cable Installation (Regulation 521.10) – Clarification on wiring system support requirements, particularly regarding "premature collapse" and fire safety considerations

• Cable Installation in Walls (Regulation 522.6) – Requirements reorganised into table format for improved clarity

• Chapter 65 – Updates to periodic inspection and testing requirements

 

Why These Changes Matter

Amendment 4 addresses the reality that electrical installations are evolving faster than ever before. From renewable energy integration and battery storage systems to smart building technology and electric vehicle charging, the amendment ensures BS 7671 keeps pace with industry innovation whilst maintaining the highest safety standards.

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The changes reflect the UK's obligations as members of CENELEC (the European standards body) to incorporate harmonised standards, as well as requirements from UK legislation including the Building Safety Act.

 

What Happens Next

The IET and BSI are currently reviewing feedback from the public consultation process. Once finalised, Amendment 4 will be published in 2026, at which point electrical professionals will need to update their working practices and documentation to reflect the new requirements.

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Pre-orders for Amendment 4 publications and associated training courses will become available ahead of the official release date.