BS 7671 Amendment 4 (2026): What's Changed and When It Applies

The IET and BSI published Amendment 4 (2026) to BS 7671:2018 on 15 April 2026. It is the most substantial update to the Wiring Regulations since the 18th Edition first appeared in 2018, adding new content for battery energy storage, Power over Ethernet, and medical locations, and bringing the standard further into line with the latest CENELEC and IEC documents.

This is a plain-English summary of what changed and the deadlines you need to know. It is not a clause-by-clause technical guide, and it does not replace reading the standard itself. The point here is simple: know what moved, know when the old version stops applying, and make sure the right edition is on your paperwork.

The Dates That Matter

An amendment to BS 7671 does not flick a switch overnight. There is a transition window where both versions are recognised, then the previous version is withdrawn.

In practice, work designed during the six-month overlap can still be certified to the previous version under the usual transitional arrangements. Once the old version is withdrawn in October 2026, new design work is expected to follow Amendment 4. As always, the certificate records the standard the installation was designed and verified against, so the edition you cite needs to match the work you actually did.

What's New in Amendment 4

Stationary battery energy storage

Amendment 4 adds a new chapter covering stationary secondary batteries, reflecting how common home and commercial battery storage has become alongside solar PV and EV charging. It pulls the requirements for the design and safety of battery energy storage systems into the standard itself, including topics such as bidirectional inverters and the location, ventilation and fire considerations for battery installations. If you install or inspect storage systems, this is the section to read first.

Power over Ethernet (new Section 716)

A new Section 716 covers Power over Ethernet (PoE), where extra-low-voltage DC is delivered over data cabling to power devices like cameras, access points and lighting. As more building services run over structured cabling, the standard now sets out how those circuits should be treated.

Medical locations (Section 710 revised)

Section 710 for medical locations has had a major revision, including how medical areas are classified into groups and the requirements that follow for each. This mostly affects those working in healthcare premises rather than domestic sparks, but it is one of the larger changes in the amendment.

Wider alignment with international standards

Beyond the headline additions, Amendment 4 continues the adoption of harmonised CENELEC documents and IEC standards as the UK keeps pace with new and developing technology. There are smaller updates and clarifications throughout, which is why reading the actual amendment beats relying on any single summary, including this one.

What It Means for Your Certificates

The most practical impact for day-to-day work is on your paperwork. Every electrical certificate states the edition of BS 7671 the installation has been designed, constructed, inspected and tested to. After Amendment 4 is in force, that reference needs to reflect the current standard for new work.

If you write your certificates by hand or use old-format templates, the standard reference is one more thing to keep on top of every time. Digital certificates keep the edition and model forms current for you, so the version on the document matches the regs in force when you issued it. You can see the electrical certificates CertBox supports and produce them on any device.

Do You Need to Retrain?

There is no overnight requirement to re-sit a qualification the day an amendment lands. Over time, the 18th Edition exams and competent-person scheme assessments are updated to include the new content, and CPD on the changes is widely available from the IET, NICEIC, NAPIT and the major training providers. The sensible move is to read the amendment, take any update training your scheme recommends, and make sure your certificates and registers reflect the current edition.

For the official detail and to buy the amendment, see the IET's official announcement.

Published June 2026. This article is for general guidance only and does not constitute legal or professional advice. Always refer to BS 7671 and the relevant official guidance, and consult your competent-person scheme for definitive requirements.