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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of old version: The previous consolidated version, the familiar Brown Book (BS 7671:2018 + A2:2022 + A3:2024) will be withdrawn six months later (mid-October 2026)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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For more information on Understanding Amendment 4 (2026) to BS 7671:2018: Key Changes to the 18th Edition IET Wiring Regulations talk to EPIT Group