When does BS 7671 Amendment 4 become mandatory?

Amendment 4 can be applied immediately from its publication date of 15 April 2026. The previous version of the regulations (BS 7671:2018+A3:2024) is formally withdrawn on 15 October 2026, after which all new electrical work in the UK must comply with Amendment 4.

Does Amendment 4 affect my home?

For most homeowners, Amendment 4 makes no immediate difference to existing wiring. If you are installing or already have a home battery storage system, the new Section 745 requirements for location, ventilation and DC isolation are relevant and should be discussed with your installer.

What does Section 745 require for battery storage?

Section 745 covers stationary secondary batteries (home battery storage systems). Key requirements include location restrictions (batteries should not be in escape routes and face specific conditions in loft spaces), adequate ventilation to manage any gas release, proper DC isolation arrangements, and attention to fire separation from living areas.

What is the Orange Book?

The Orange Book is the informal name for the BS 7671:2018+A4:2026 publication. It consolidates all four amendments (A1, A2, A3 and A4) into a single document, making it easier to use than maintaining the base edition plus separate amendment documents.

Understand BS 7671 Amendment 4: What Changed in the 2026 Wiring Regulations

Helpful video reference. The Institution of Engineering and Technology (IET), the body that publishes the UK wiring regulations, hosted the live launch event for Amendment 4 on 15 April 2026. The recording, "Amendment 4: 2026 to BS 7671:2018 18th Edition of the IET Wiring Regulations Launch", gives a thorough overview of the new content from the authors of the regulations themselves. If you want the detail behind any of the sections, this is the best place to start.

For homeowners. This guide explains what Amendment 4 changes, not how to carry out electrical work yourself. The regulatory update affects the standards your electrician must work to, particularly for battery storage installations. If you have a battery storage system that was installed before April 2026, it does not need to be immediately altered, but it is worth asking your electrician to check it at your next EICR.

1. What is BS 7671 Amendment 4?

BS 7671 is the IET Wiring Regulations: the technical standard that all UK electrical installation work must comply with. The current edition is the 18th, published in 2018. Since then it has been updated four times: A1 (2020), A2 (2022), A3 (2024), and now A4 (2026).

Amendment 4 is published as a single consolidated document, BS 7671:2018+A4:2026, sometimes referred to informally as the Orange Book. It replaces the previous version of the regulations from 15 October 2026. Electricians can apply Amendment 4 immediately from its publication date, and many will do so well before the deadline. From October 2026 onwards, any new electrical work should be certified to the new version.

2. The main domestic change: Section 745 — battery storage

The most significant addition for homeowners is Section 745, covering stationary secondary battery installations. This means home battery storage systems: the units increasingly paired with solar panels, or used to charge overnight on cheap-rate tariffs.

Section 745 sets requirements in several areas:

Location: batteries must not be installed in escape routes. In loft spaces, specific conditions apply to manage the fire risk. The regulations restrict siting in areas where a fault or fire would block a means of escape.
Ventilation: where the battery chemistry could release gas under fault conditions, adequate ventilation is required to prevent accumulation.
DC isolation: the DC supply from the battery must be isolatable independently from the AC side of the system, using devices rated for DC breaking duty.
Bidirectional energy flow: because batteries both charge and discharge, the installation design must account for current flowing in both directions.

If you are getting a battery storage system installed after April 2026, your installer should be designing to Section 745. Ask them directly which version of BS 7671 they are working to and what Section 745 measures they are including in the installation.

3. Section 545 — ICT earthing

A new Section 545 distinguishes between two types of earthing in ICT installations: protective earthing (connecting metalwork to earth for safety against fault current) and functional earthing (earthing required for the correct operation of equipment, not for personal safety). Both types existed before Amendment 4, but the new section gives clearer rules for when functional earthing is needed and how it should be provided without compromising the protective earthing system.

In most homes, this section has no immediate impact. It becomes relevant if you are installing a server room, a complex smart home control system, or sensitive communications equipment.

4. Section 716 — Power over Ethernet

Section 716 covers Power over Ethernet (PoE): the technology that delivers both data and low-power DC electricity through a standard network cable. It is commonly used for IP cameras, access control panels, smart lighting controllers and similar devices.

The new section gives specific installation guidance for PoE systems, including cable selection, current limits and protection against overloading the Ethernet cabling. Again, most domestic homes are not affected unless PoE-powered devices are being installed.

5. Section 710 — Medical locations

Section 710, covering medical locations (operating theatres, hospital treatment rooms, and similar specialist environments), has been substantially revised. This section has no application to standard domestic electrical work.

6. The transition timeline

Amendment 4 was published 15 April 2026. The previous version of the regulations, BS 7671:2018+A3:2024, remains valid alongside Amendment 4 until 15 October 2026. After that date, it is formally withdrawn.

In practice, the six-month transition period means:

Electrical work started and completed before October 2026 can be certified to either version.
From October 2026, all new work should be certified to BS 7671:2018+A4:2026.
EICRs on existing installations after October 2026 will be issued against Amendment 4.

7. What this means for your home

For straightforward domestic electrical work (replacing sockets, fitting switches, adding lighting, fuse board replacement), Amendment 4 makes no difference to what you notice on the day. The existing wiring in your home does not need to be modified simply because the regulations have been updated.

The areas where Amendment 4 directly matters to homeowners are:

New battery storage installations: check your installer knows about Section 745 before work starts.
EICRs issued after October 2026: these will reference the new edition.
Any work on a complex smart home system with PoE components: Section 716 applies.

If you have existing battery storage. A battery system installed before Amendment 4 does not automatically fail to comply, as existing installations are assessed against the regulations in force when they were installed. However, if the installation is in a location that Section 745 would now consider unsuitable (such as directly adjacent to a staircase), it is worth having an electrician look at it and give you a written opinion at your next inspection.

When to call us

Richard issues EICR certificates and installation certificates to the current version of BS 7671. If you want a safety inspection to the new Amendment 4 standard, or if you are planning a battery storage installation and want to discuss the Section 745 requirements, get in touch.

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Richard issues EICR certificates to BS 7671:2018+A4:2026 for landlords, homeowners and buyers. Reports in plain English, action list included if remedial work is needed.

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Understand BS 7671 Amendment 4: what changed in 2026