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 brings the UK's electrical installation standards in line with evolving European harmonised standards and addresses rapidly emerging technologies in the electrical sector. Importantly, Amendment 4 is a fully consolidated edition that brings together the original 2018 regulations and all subsequent amendments into a single document, commonly referred to in the industry as the Orange Book.

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Timeline of Events

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

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

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

15th January 2026 - IET and BSI signed off the content for Amendment 4 and announced its upcoming publication

15th April 2026 – Amendment 4 officially published; available to purchase and implement immediately

15th October 2026 - BS 7671:2018+A2:2022+A3:2024 withdrawn (six months after publication) Brown book 

(Diagram showing the timeline click here)

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Current Compliance Requirements

Amendment 4 (BS 7671:2018+A4:2026) is available to implement immediately from 15th April 2026. The previous consolidated version —

BS 7671:2018+A2:2022+A3:2024, remains valid during a six-month transition period and will be withdrawn on 15th October 2026. From 16th April 2026 until 15th October 2026, electrical installers may work to either the previous version or Amendment 4.

Note that Amendment 3:2024 has been incorporated into the main Amendment 4 document rather than remaining as a separate bolt-on download.

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Changes in Amendment 4

The amendment has been developed in response to rapid technological developments and incorporates 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 – SStationary secondary battery installations, addressing the significant growth in battery storage systems, including requirements for system design, power conversion equipment, bidirectional or hybrid inverters, battery location, ventilation, and fire-risk mitigation

• Section 716 – Power over Ethernet (PoE), introducing requirements for the use of Ethernet cabling to supply extra-low voltage DC to equipment such as LED lighting and small appliances, using SELV and PELV systems. Voltage limits are modified to 60 V ripple-free DC in dry locations and 15 V ripple-free DC elsewhere. All electrical connections must comply with BS ISO/IEC 11801-1 and support a continuous operating current of 750 mA per contact

• Major revision of Section 710 – Medical Locations, now classifying medical locations into Groups 0, 1 and 2, with enhanced requirements for Group 2 areas such as operating theatres. These updates align the UK with IEC 60364-7-710:2021 and its CENELEC adoption

• 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. BSI has noted that BS 7671 underpins safe, modern electrical infrastructure — essential for delivering the electrification needed to meet the UK's 2030 clean energy goals.

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​As with Amendment 2 in 2022, Amendment 4 is published as a fully consolidated document rather than a bolt-on amendment — meaning the industry has a single, up-to-date Orange Book incorporating all previous amendments, rather than needing to cross-reference multiple documents.

 

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