BS 7671 Amendment 4:2026 Explained: Key Changes Before 15 October

BS 7671 Amendment 4:2026 is the latest major update to the UK’s national standard for electrical installations. It was published on 15 April 2026, but that did not make every older installation unsafe overnight or require electricians to abandon the previous edition immediately.

There is a six-month transition period. Until 14 October 2026, new work can use either Amendment 4 or the previous Brown Book requirements with Amendment 3. From 15 October 2026, the previous version is withdrawn and Amendment 4 becomes the edition to use for work designed to BS 7671.

This guide explains the change in ordinary language, including what it means for homeowners, landlords, trainees, and working electricians.

Important: This article is a general introduction, not a substitute for BS 7671, its official guidance, manufacturers’ instructions, or a competent electrical design. Do not use a summary article to specify, install, inspect, or certify electrical work.

The Quick Answer

The new book has an orange cover, so it is often called the Orange Book. It is still the 18th Edition. It is not the 19th Edition and it does not turn BS 7671 into a new law.

The most visible additions concern:

• Stationary battery storage systems
• Power delivered through data cables, including Power over Ethernet
• Functional earthing and bonding for information and communication technology
• Electrical installations in medical locations
• Wider updates involving fire safety, bidirectional power flow, energy efficiency, protective devices, inspection, and reporting

What Is Amendment 4?

BS 7671 sets out requirements for the design, erection, and verification of electrical installations. It is jointly published by the Institution of Engineering and Technology (IET) and BSI.

The full name of the new standard is BS 7671:2018+A4:2026. Amendment 4 brings the earlier 18th Edition changes together in one book and adds new requirements for technologies that are becoming more common in real installations.

That matters because buildings no longer only consume electricity in one direction. A home may generate power through solar panels, store it in a battery, charge a vehicle, run connected equipment, and sometimes send energy back towards the network. Data cabling may also carry useful electrical power instead of data alone.

The IET and BSI publication announcement confirms the publication date, transition period, and principal areas of change. The IET also provides an edition checker for identifying the current requirements.

Does Every Existing Installation Need Upgrading?

No. Amendment 4 is not an automatic instruction to rewire every property completed under an earlier edition.

Electrical standards develop over time. An existing installation may not match every detail of the newest edition and may still be suitable for continued use. Its condition, risks, protective measures, and the rules that applied when it was installed all matter.

This means Amendment 4 does not, by itself, mean that:

• An older consumer unit must be replaced immediately
• A correctly installed home battery must automatically be moved
• A property must be rewired because its certificate names an earlier edition
• An Electrical Installation Condition Report must be unsatisfactory solely because the installation is older

An inspection should assess the installation that actually exists. Defects are coded according to the danger or potential danger they present, not simply because a newer book has been published. Our guide to EICR codes C1, C2, C3 and FI explains that risk-based approach.

The IET addresses this directly in its guidance on Amendment 4 misconceptions: BS 7671 is not retrospective, although existing work may need attention when an assessment identifies a real safety problem.

The Main Changes in Plain English

Amendment 4 is a large technical document. The following sections explain its main new subjects without attempting to reproduce the requirements themselves.

1. Battery Storage Gets a Dedicated Chapter

The new Chapter 57 covers stationary secondary battery systems used to store and supply electricity to an installation.

In plain language, these are rechargeable batteries fixed in place as part of a building’s electrical system. A domestic solar battery is a familiar example, but the chapter is not limited to homes or solar installations. Some batteries built into products covered by other standards fall outside its scope, so the product and installation context both matter.

A battery changes the behaviour of an installation. Power may come from the public supply, local generation, the battery, or more than one source at once. Some equipment can move energy in both directions. Turning off the normal incoming supply may therefore not remove every source of electrical energy.

The new chapter gives designers and installers a clearer framework for considering matters such as:

• The type and capacity of the battery system
• Power conversion equipment, including bidirectional and hybrid inverters
• Isolation and protection where current can flow in more than one direction
• Cable and protective-device selection
• The battery’s location and surrounding conditions
• Ventilation, heat, fire risk, and access
• Labelling, documentation, inspection, and maintenance

For domestic installations, other documents and manufacturers’ instructions still matter. Amendment 4 does not turn battery design into a simple checklist, and it does not make every available location suitable.

Homeowners considering storage should begin with the purpose of the system, the expected loads, the existing supply, and a competent survey. Our plain-language guide to solar PV and battery storage explains how generation, inverters, batteries, and the grid fit together.

2. Power over Ethernet Is Now Covered Directly

The new Section 716 addresses extra-low-voltage DC power distribution over information and communication technology cabling. Power over Ethernet, usually shortened to PoE, is the best-known example.

PoE allows one data cable to carry both communication and electrical power. It is commonly used for devices such as:

• Wireless access points
• Internet protocol cameras
• Door-entry equipment
• Networked telephones
• Sensors, controls, and connected lighting equipment

It may look like ordinary network cabling, but carrying power introduces electrical design questions. The source, cable, connectors, route, grouping, temperature, current, and connected equipment all have to work together safely.

This becomes especially important when many powered cables are bundled. Heat that is insignificant in one cable can become relevant across a large group, while poor connectors or unsuitable components can create local problems.

Section 716 gives these systems a clearer place within BS 7671. It does not mean that every network lead now requires an electrician, but a permanently installed powered cabling system cannot be treated as though electrical performance is irrelevant.

Good routes, support, segregation, and protection remain important. See cable clipping and containment for the basic principles used when planning safe cable runs.

3. Functional Earthing and Bonding Are Clarified

The new Section 545 deals with functional earthing and functional equipotential bonding for information and communication technology equipment.

The word functional is important. Protective earthing exists primarily to reduce electric-shock risk when a fault occurs. Functional earthing or bonding may be needed so equipment operates correctly, limits interference, or maintains signal performance.

The two purposes are related, but they are not interchangeable. A connection introduced for equipment performance must not weaken, bypass, or confuse the protective measures that keep people safe.

This subject is increasingly relevant in buildings containing data networks, control systems, communications equipment, and sensitive electronics. Amendment 4 provides a more defined approach to coordinating those systems with the electrical installation.

For the safety side of the distinction, read main protective bonding explained and our overview of TN-S, TN-C-S and TT earthing systems.

4. Medical Locations Receive a Major Revision

Section 710, which covers medical locations, has been substantially revised.

Medical electrical installations require additional care because an interruption, wiring fault, or small electrical disturbance can have consequences beyond those expected in an ordinary room. The appropriate measures depend on how the space is used and which medical procedures take place there.

The update covers areas including resilience of supply, monitoring, supplementary bonding, verification, and recording results. These are specialist requirements intended for healthcare environments and competent professionals working in that field.

They do not turn an ordinary bedroom, bathroom, or home office into a medical location because someone uses consumer health equipment there. Classification and design depend on the actual clinical use of the location.

5. Other Requirements Have Also Changed

The four subjects above are the easiest headline changes to describe, but Amendment 4 is not limited to four new sections.

The wider revisions include changes relating to:

• Fire safety and wiring in protected escape routes
• Coordination between protective devices
• Generating sets and systems with bidirectional power flow
• Energy efficiency and prosumer electrical installations
• Inspection, testing, reporting, and supporting evidence
• Protective-device requirements incorporated from Amendment 3:2024, alongside later clarifications and corrections

Electricians therefore need to review the full amendment, not only learn the new battery chapter. Electrical Safety First’s Amendment 4 pocket guide offers a useful overview, but the guide and this article are both summaries rather than replacements for the standard.

What Amendment 4 Means for Homeowners and Landlords

Most homeowners do not need to buy the Orange Book or redesign their electrical installation. The practical points are simpler.

Existing installations do not automatically fail

The publication of Amendment 4 does not, on its own, make an older property unsafe. Continue to arrange inspection at the appropriate interval and act on defects that a competent person identifies.

New energy systems need joined-up design

If you plan to add solar PV, a stationary battery, an electric vehicle charger, or equipment that can export energy, make sure the designer considers the installation as a complete system. Adding one product can affect isolation, protection, labels, maximum demand, earthing, and the direction of power flow.

Ask which edition applies to planned work

For work taking place near the October changeover, ask the designer or installer which edition the design follows and make sure that choice is recorded. A project that crosses the transition date may need careful contractual and technical review rather than an assumption based only on the installation date.

Keep certificates and system information

Retain electrical certificates, schedules, equipment manuals, commissioning records, and any diagrams supplied with the work. They help future electricians understand the design and inspect it properly. Our guide to EICs, EICRs and Minor Works Certificates explains what the common documents are for.

Landlords should also remember that their legal duties and inspection requirements exist separately from the publication of a new BS 7671 amendment. A change of book colour does not reset an inspection interval or replace the need to act on a report.

What Electricians and Trainees Should Do Before 15 October

The transition period is intended to give the industry time to prepare. A practical plan includes more than buying the new book.

1. Confirm the dates. Know when the earlier edition can still be used and when it is withdrawn.
2. Read the actual amendment. Summaries help with orientation, but they omit the definitions, exceptions, notes, tables, and relationships between regulations.
3. Update reference material. Review design software, forms, checklists, model certificates, company procedures, and training notes.
4. Check projects in progress. Record the edition used for each design and review work that spans the transition date with the responsible designer, client, and certifier.
5. Study beyond the headline chapters. Battery storage and PoE attract attention, but changes elsewhere can affect everyday design, installation, and inspection.
6. Review manufacturer requirements. Product instructions remain essential, particularly for inverters, batteries, protective devices, controls, and powered communication equipment.
7. Keep evidence clear. Certificates, schedules, labels, photographs, commissioning information, and design records should allow another competent person to understand what was installed and why.

Training providers and employers should update learning material carefully. Teaching only a list of new section numbers may help with recall, but it does not explain how multiple sources, protection, isolation, cable routes, and equipment interact in a real installation.

Is BS 7671 the Law?

BS 7671 is a British Standard, not an Act of Parliament. Its publication on 15 April did not create a new criminal offence, and the 15 October withdrawal date is not the same as Parliament passing a new electrical law.

However, that does not make the standard optional in any casual sense. UK legislation places duties on people responsible for electrical work and safety. Following the applicable edition of BS 7671 is a widely recognised way to demonstrate that an installation has been designed and erected to an appropriate safety standard.

Other legal and contractual requirements may apply depending on the building and the work. In England and Wales, for example, Part P of the Building Regulations concerns electrical safety in dwellings and includes notification requirements for certain work.

The sensible distinction is:

• The law sets duties and outcomes.
• BS 7671 provides detailed technical requirements used to help meet them.

Anyone responsible for a particular project should check the legislation, contract, standard, and guidance that apply to that work rather than relying on a general article.

Frequently Asked Questions

Is Amendment 4 the 19th Edition?

No. BS 7671:2018+A4:2026 remains the 18th Edition. The orange cover identifies the latest consolidated version; it does not change the edition number.

Can the Brown Book still be used?

During the transition period, yes. The previous BS 7671:2018+A2:2022 requirements, together with Amendment 3:2024, can be used until 14 October 2026. From 15 October 2026, that combination is withdrawn, leaving Amendment 4 as the sole current edition.

Must an existing home battery be moved?

Not merely because Amendment 4 has been published. An existing system should be assessed on its design, condition, location, documentation, and actual risks. Work to alter or extend it should follow the requirements applicable to that work.

Will an older installation fail an EICR because of Amendment 4?

Not solely because it was installed to an earlier edition. An EICR records the condition and safety of the installation at the time of inspection. Observations and codes should reflect the risk found, not just the age of the regulations named on an old certificate.

Does Amendment 4 apply only to electricians?

Electricians, designers, inspectors, and other electrical professionals need the technical detail. Homeowners, landlords, facilities teams, network specialists, and clients also benefit from understanding the transition date and recognising when new technology needs competent electrical design.

Can ElectraSim confirm that a design complies with Amendment 4?

No. ElectraSim is an educational circuit simulator. It can help learners visualise connections, switching, current paths, and protection concepts, but it does not perform a BS 7671 compliance assessment or replace calculation, inspection, testing, certification, or professional judgement.

Learn the Principles with ElectraSim

Regulation changes are easier to understand when the electrical behaviour behind them is clear. In the ElectraSim wiring lab, you can build and test educational circuits, trace current paths, operate switches, and explore fault behaviour without working on a live installation.

Use the simulator to strengthen your understanding of circuit principles, then use the official standard, guidance, product information, and competent supervision for real design and installation work.

Summary

BS 7671 Amendment 4:2026 was published on 15 April 2026. After the transition period ends on 15 October 2026, the previous edition is withdrawn. Amendment 4 remains part of the 18th Edition and is commonly recognised by its orange cover.

Its main additions give battery storage, powered data cabling, functional earthing for ICT systems, and medical locations clearer treatment. Other changes affect familiar areas such as fire safety, protective devices, energy flow, inspection, and reporting.

For existing properties, the message is not to replace everything. The new amendment is not retrospective, and electrical condition should be judged by evidence and risk. For new work, the important steps are to identify the applicable edition, use the full standard, coordinate the whole system, and keep clear records.

Safety reminder: Electrical installation work can cause electric shock, fire, or death if it is designed or carried out incorrectly. Use a competent, appropriately registered electrician for work on a real installation.