BS 7671 Amendment 4 Now Applies: What Changes on Your Next Job

Since 15 October 2026, BS 7671 Amendment 4 has been the only current version of the Wiring Regulations. Anything you design, install or inspect from now on follows it, and the certificates and condition reports for that work should say so. The one exception is work you designed before 15 October. NICEIC’s guidance is that you can finish it to the previous version, provided the client knows.

BS 7671 is the British Standard for low-voltage electrical installations, published by the Institution of Engineering and Technology (IET) and BSI. It is not a law in itself. The Health and Safety Executive’s guidance, HSR25, calls it “non-statutory regulations” and says compliance with it “is likely to achieve compliance” with the Electricity at Work Regulations 1989. In homes in England, the legal duty is requirement P1 in Part P of the Building Regulations 2010, and BS 7671 is the recognised way to meet it. Scheme rules then add their own requirement: NICEIC, for one, makes access to the current version a condition of certification.

What changed on 15 October

The IET and BSI published BS 7671:2018+A4:2026 on 15 April 2026. For six months, you could work to either version. In the IET’s words, Amendment 3 “remains a valid standard until 15 October 2026”. On that date the previous version, BS 7671:2018+A2:2022+A3:2024 and its 2023 corrigendum, went out of date. NAPIT and NICEIC both confirm its withdrawal.

NICEIC tells registered businesses to apply Amendment 4 to “all new electrical installations, modifications to existing installations, and periodic inspections and testing”. You also need to show access to a copy of Amendment 4 at your next assessment. NICEIC lists the book at £125 RRP. Qualified supervisors who already hold an 18th Edition qualification don’t have to requalify. NICEIC does expect them to know the changes that affect their own work and to do relevant CPD.

Jobs you designed before 15 October

Say you priced a consumer unit change and a kitchen rewire on 1 October, and the work starts next week. NICEIC’s answer is: “if it’s been designed before that date, you can complete it to the previous standard, even after 15 October.” SELECT, the Scottish electrical trade association, puts it the same way, “subject to contractual arrangements agreed”.

That permission comes with conditions worth acting on before the first day. NICEIC recommends telling the client that the design follows a withdrawn standard, because they may expect the latest one. Check whether your contract says the work will meet the “latest” version of BS 7671. An insurer or licensing authority may say the same. And if Amendment 4 would change the design, decide whether that changes the price. Where it makes no difference to the job, NICEIC suggests telling the client so, and certifying to Amendment 4 if you can.

The certificate then follows the design. NICEIC says you certify work started before 15 October to the version you designed it against. On the declaration, you date Amendment 4 work “BS 7671 2026”, and work completed to Amendment 3 “BS 7671 2024”. New work started on or after 15 October needs Amendment 4 certificates. On NICEIC’s online forms, version 18.4 is Amendment 4 and 18.3 is Amendment 3.

Battery storage now has its own chapter

The change most domestic electricians will meet first is Chapter 57, on stationary secondary batteries. It covers batteries used to store energy and supply an installation, which is the battery on a solar job or a stand-alone home storage system. According to the IET and BSI’s launch announcement, it sets requirements for “system design, power conversion equipment, bidirectional or hybrid inverters and the suitability of protective devices for two‑way energy flow”. It also puts weight on battery location, ventilation and fire risk.

SELECT’s summary of the amendment adds the detail around it. The standard now treats a stationary battery as a generating set, not a load. Protective devices must suit two-way energy flow where it occurs. And under certain conditions you must not connect a source on the load side of an RCD. Those points come from a trade association’s overview, not the standard itself, so check the exact regulations in your copy before you design.

For a solar and battery quote, that means checking the inverter and protective devices against the new chapter before you price. NICEIC confirms two practical points. BS 7671 doesn’t require an AFDD on the circuit supplying a battery energy storage system. And on the schedule you record the British Standard of the protective device, not whether it is bidirectional.

EICRs: an FI no longer fails the report

The Electrical Installation Condition Report has changed most. Its observations section is now in two parts. Observations coded C1 or C2 go in the first part, and they make the overall outcome unsatisfactory. Observations coded C3, or calling for further investigation (FI), go in the second part, and NICEIC says these “DO NOT affect the overall outcome of the report”.

Under Amendment 3, an FI made the report unsatisfactory. Under Amendment 4, it doesn’t. The FI code also loses its “without delay” wording. NICEIC’s explanation is that FI “has sometimes been incorrectly used”, for example where too little time was allowed for the inspection. So budget enough time to inspect properly, and expect clients to ask why the result reads differently from their last report.

Landlords need more care. The Electrical Safety Standards in the Private Rented Sector and Social Rented Sector (England) Regulations 2020 are law, enforced by local housing authorities. They require inspection and testing at least every five years against the 18th Edition, BS 7671:2018. Where a report requires further investigative or remedial work, regulation 3(4) gives the landlord 28 days, or less if the report says so. The government’s guidance, published in November 2025, still describes FI as investigation “required without delay”. So don’t tell a landlord client that an FI can wait. Explain what the new report layout means, and what the report asks them to do.

PNB earthing and the smaller paperwork changes

BS 7671 now recognises protective neutral bonding (PNB) for the first time, as a form of TN-C-S earthing. You can now select it as the earthing arrangement on the forms. NICEIC passes on two indicators from the Energy Networks Association. A supply with more than four energy consumers can’t be PNB, and nor can one where the earth electrode is more than 40 metres from any of them. If you aren’t sure, the network operator has to tell you the earthing type free of charge.

A few other changes reach domestic work:

• On Minor Works certificates, the end-to-end tests now read r1–r1, rn–rn and r2–r2 instead of L/L, N/N and cpc/cpc.
• The AFDD rule is unchanged apart from a new term. Four building types still need AFDDs on socket-outlet circuits up to 32 A: care homes, high rise residential buildings, houses in multiple occupation and purpose-built student accommodation.
• A new informative note says RCDs in series should suit the type of residual current expected, according to SELECT.
• New sections cover Power over Ethernet (Section 716) and functional earthing for IT equipment (Section 545).

Paper and electronic forms both continue. Notification is a separate question from the version you certify to, and our guide to Part P notification covers which jobs need it. If you aren’t registered with a scheme, building control is the other route.

Scotland, Wales and Northern Ireland

BS 7671 is a UK-wide standard, so Amendment 4 applies to your design wherever you work. The building rules that rely on it differ. Wales has its own version of Part P. Scotland’s building standards technical handbooks point to BS 7671 for electrical safety. Northern Ireland’s Building Regulations 2012 have no electrical part at all; there, electrical work falls under the Electricity at Work Regulations (Northern Ireland) 1991.

Older installations aren’t suddenly unsafe or unlawful. HSE’s guidance says an installation built to an earlier edition, then current, would not for that reason alone fail to comply with the Electricity at Work Regulations. What changes is the version your next design, certificate and report follow. The book, the training and the extra time on battery jobs all belong in your rates, which our UK electrician rates guide helps you build.