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. the information given below is based on the draft for public comment (DPC) that was avaialble between August and 

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What is BS 7671 Amendment 4?

It is the next update to the UK Wiring Regulations (BS 7671:2018), expected to introduce revisions in safety, design practices, testing, and guidance for emerging technologies.

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When will Amendment 4 be released?

An announcement was made by The IET on the 15th January 2026, that the IET Wiring Regulations BS 7671:2018+A4:2026 would be published on the 15th April 2026.

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Will Amendment 4 be mandatory immediately?

The Brown Book (BS 7671:2018+A2:2022) remains valid until 15 October 2026, but The Orange Book (BS 7671:2018+A4:2026) marks the next step forward.

Historically, new amendments typically include a 6-month implementation period during which installations can comply with either the old or new standard. Until Amendment 4 is published, electrical professionals must work to BS 7671:2018+A2:2022 (the brown book), the May 2023 Corrigendum, and Amendment 3:2024.

 

From the 15th of October 2026, the Orange Book (BS 7671:2018+A4:2026) must be used.(Diagram showing the timeline click here).

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How will Amendment 4 affect electrical work?

​Changes may impact design standards, consumer unit configurations, testing procedures, and documentation requirements.

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What is Chapter 57 and what does it cover?

Chapter 57 is a new addition to BS 7671 that sets out detailed requirements for the installation of stationary secondary battery systems used to store and supply electricity. This chapter addresses the rapid growth in domestic and commercial battery storage installations, including systems connected to solar PV arrays and standalone energy storage solutions. The chapter applies to battery systems intended for permanent installation where their main purpose is to store and supply electrical power. This represents one of the most significant additions to Amendment 4, reflecting the increasing prevalence of battery storage technology in UK electrical installations.

 

What is Section 545 about?

Section 545 gives additional requirements for functional earthing and functional-equipotential-bonding for information communication technology equipment and systems (ICT), such as broadcast, communication technology and computer network systems. This new section makes a clear distinction between functional earthing (required for equipment operation) and protective earthing (required for electrical safety). It's important that any interruption of the functional earthing does not impair the protective earthing. The section includes requirements for minimum cross-sectional area, identification, electrical continuity of functional bonding conductors, combined protective and functional bonding conductors, main functional earthing terminal, and equipotential bonding ring conductors.

 

What is Section 716 and how does it relate to Power over Ethernet?

Section 716 sets out requirements for the distribution of extra-low voltage (ELV) DC power using structured cabling systems typically designed for data transmission. This includes Power over Ethernet (PoE) installations, which are increasingly common in modern buildings for IP cameras, wireless access points, VoIP phones, and smart building systems. The section ensures that data cabling systems used for power (like PoE) are treated with the same electrical safety considerations as conventional ELV systems. Where existing telecommunications cabling is repurposed for PoE, it must be assessed to confirm suitability for power transmission, and installations must be tested to ensure they meet both data performance and electrical safety requirements.

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What changes are proposed for ferromagnetic enclosures?

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Regulation 521.5.1 concerns ferromagnetic enclosures and electromagnetic effects. The DPC includes a new note stating that for low voltage switchgear and controlgear assemblies to the BS EN IEC 61439 series, conductors in AC circuits with a current rating not exceeding 200 A can pass through separate holes in ferromagnetic enclosures, sections, or plates. However, currents above 200 A where conductors pass through separate holes in ferromagnetic material need to have been verified by temperature-rise test(s). This clarification addresses practical installation scenarios while maintaining safety standards for electromagnetic effects.

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What does Regulation 521.10.202 about "premature collapse" mean?

Regulation 521.10.202 states that "Wiring systems should be supported such that they will not be liable to premature collapse". This regulation was introduced to prevent wiring systems from hanging, which may hinder evacuation or obstruct firefighting activities in the event of a fire. Since its introduction, the regulation has raised several questions, so Amendment 4 introduces a note explaining the intent and clarifying that it is not intended to provide support to maintain circuit integrity of life safety and firefighting applications under fire conditions (which are addressed in Chapter 56 and BS 5839, BS 5266, and BS 8519). The key focus is on preventing cables from becoming hazards during emergency situations.

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How have the requirements for cable installation in walls (Regulation 522.6) changed?

The requirements of Regulation 522.6 (a cable installed in a wall or partition) have been reorganized into a table for improved clarity, though it is understood that the actual requirements have not been changed. This reorganisation makes it easier for electricians and designers to quickly reference the correct installation methods for cables in walls and partitions. The table format provides a clearer, more user-friendly approach to understanding compliance requirements, reducing the likelihood of misinterpretation during installation work.

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Are there new requirements for Arc Fault Detection Devices (AFDDs)?

The DPC proposes new mandatory requirements for AFDDs on electric vehicle charging installations (EVCIs). This addition recognises the particular fire risks associated with EV charging equipment and the extended periods of high-current loading typical of vehicle charging. While AFDDs have been part of BS 7671 since Amendment 2, extending their requirement to EVCI installations represents a significant safety enhancement for this rapidly growing sector of electrical work.

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What changes affect RCD protection for outdoor lighting?

The Draft for Public Comment includes updated RCD requirements for outdoor lighting installations. These updates address the specific risks associated with outdoor electrical equipment exposed to weather conditions and potential mechanical damage. The changes ensure adequate protection against electric shock for garden lighting circuits and other outdoor electrical installations, reflecting modern installation practices and product developments in outdoor lighting systems.

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What updates are proposed for Chapter 65 on inspection and testing?

Amendment 4 introduces several important updates to Chapter 65 concerning periodic inspection and testing. Regulation 653.1 now requires the notes for the person producing the report (provided in Appendix 6) to be taken into account on the Condition Report. Additionally, Regulation 653.2 now requires the report to include guidance for the recipient(s) based on the model in Appendix 6. A significant practical addition is a new note pointing out that photographic and/or thermographic images can be appended to the report. There is also clear confirmation that the signatures on reports must be from those conducting the inspection and authorising the report. These changes improve accountability, enhance the quality of reporting, and provide greater flexibility for electricians to include visual evidence of installation conditions or defects in their EICR documentation.

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Is there a new chapter on energy efficiency?

Yes. Chapter 81 is a new chapter introduced in Amendment 4 that focuses on improving energy efficiency in low-voltage electrical installations. At this stage, Chapter 81 serves as an introductory framework signaling a broader focus in BS 7671 on energy performance. Further detail is expected in future editions or supporting documents. This addition reflects the UK's commitment to net-zero targets and the Building Safety Act requirements, ensuring that electrical installations contribute to overall building energy efficiency.

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How many new definitions are being proposed?

The DPC includes 54 proposed new definitions, symbols or abbreviations, 53 proposed revisions and 15 proposed deletions. These include definitions for batteries, firefighting shaft, protective neutral bonding, and functional earthing terminology. The extensive revision of definitions ensures that Amendment 4 provides clear, unambiguous terminology for the new technologies and requirements being introduced, helping designers and installers understand and apply the regulations correctly.

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Will Amendment 4 affect TN-S earthing arrangements?

Yes, the Draft for Public Comment includes updates to TN-S earthing arrangements in modern electrical installations. These changes reflect advances in earthing technology and address specific scenarios encountered in contemporary installations, particularly those involving renewable energy systems, battery storage, and electric vehicle charging equipment. The updates ensure that TN-S earthing systems continue to provide adequate protection in installations that may include bidirectional power flow and multiple sources of supply.

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What are the new requirements for low voltage generating sets?

Section 551 covers generators with several supply arrangements, and Regulation group 551.7 sets out additional requirements for installations where the generating set may operate in parallel with other sources, including systems for distribution of electricity. A new paragraph (c) requires a suitable protective device to be installed in bidirectional energy flow scenarios. This is particularly relevant for installations with renewable energy generation, battery storage, or combined heat and power (CHP) systems that can export energy back to the grid or operate in island mode during power outages.

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Additional Notes

Source of Information: All answers are based on the Draft for Public Comment (DPC) for Amendment 4 published between 7 August and 3 November 2024. The final published version may differ based on industry feedback received during the consultation period.

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Current Compliance: Until Amendment 4 is published in 2026, all electrical work must comply with BS 7671:2018+A2:2022, the May 2023 Corrigendum, and Amendment 3:2024.

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Training: Once Amendment 4 is published, electrical professionals will need CPD training to understand and correctly apply the new requirements. Most certification bodies (NICEIC, NAPIT, ECA, etc.) will require evidence of Amendment 4 training.

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