BS 7671 Amendment 4: what changed in 2026 for London homeowners and landlords

What BS 7671 is and why it matters to you

BS 7671 is the British Standard for electrical installations, usually called the wiring regulations. It is not a law on its own, but it is the benchmark electricians work to. Building control, insurers, councils and landlord rules all lean on it. When a landlord EICR (Electrical Installation Condition Report) is carried out, the inspector compares your installation against the current BS 7671.

The current edition is the 18th, first published in 2018. It has had four amendments. The fourth, published as BS 7671:2018+A4:2026, is the one that matters now.

The key dates

Date	What happened
15 April 2026	Amendment 4 published
15 April to 15 October 2026	Transition: electricians could use either version
15 October 2026	Previous version (A2:2022 + A3:2024) withdrawn
From 15 October 2026	Amendment 4 is the only current version

These dates come from the NICEIC Amendment 4 page and the IET, which publishes BS 7671 with the British Standards Institution. Work that was designed before 15 October 2026 can still be finished and certified to the older version, but new designs and new EICRs should follow Amendment 4.

The change landlords will notice: FI codes

Every problem found on an EICR gets a code:

• C1: danger present, immediate action needed
• C2: potentially dangerous, urgent action needed
• C3: improvement recommended
• FI: further investigation advised

Under the old version, an FI code made the whole report unsatisfactory. Under Amendment 4 it does not. The observations section is now split in two. C1 and C2 go in the first part, and any of those makes the outcome unsatisfactory. C3 and FI go in the second part, and they do not change the outcome.

The NICEIC says the change was made partly because FI was sometimes used when an inspector had not allowed enough time to test properly. The words “without delay” have also been removed from the FI description.

What this means in practice for a landlord in England: the government guidance still says remedial or further investigative work identified as necessary must be done within 28 days, or sooner if the report says. An FI is still worth taking seriously. It just no longer fails the report on its own. Our guide to what to do after an unsatisfactory EICR covers the next steps.

Other changes in plain English

Home batteries. There is a new chapter on stationary secondary batteries. That covers battery storage fitted with solar panels or on its own. If you are adding a battery, expect more design checks on where it goes and how it is protected.

Power over Ethernet. A new section covers PoE, where data cables also carry power to things like cameras, wifi points and some lighting. It is now inside BS 7671 for the first time.

A new earthing type. Protective Neutral Bonding, or PNB, is recognised for the first time and can be recorded on certificates. It is a way some small groups of properties are earthed by the network. The NICEIC notes that a network operator must tell you the earthing type free of charge if asked. In most of London that is UK Power Networks; in Ealing and Hounslow it is SSEN.

Wording on AFDDs. AFDDs (arc fault detection devices) spot the tiny sparks from damaged cable. The term “higher risk residential buildings” became “high rise residential buildings”. The NICEIC is clear the requirement has not been removed, only reworded. See our guide to AFDDs in London flats.

Functional earthing for IT equipment. A new section covers earthing for data and communications kit. This matters more in offices than homes.

What it means for your home

For most London homeowners, very little changes day to day.

• If your installation was safe before, it is still safe.
• If you are having a new consumer unit, your certificate should now say it was designed to BS 7671:2018+A4:2026.
• If you are adding solar, a battery or an EV charger, expect the design to take the new rules into account.
• If you are a landlord, a report with FI codes and no C1 or C2 is now satisfactory, but the further investigation should still be done.

London’s housing makes the EICR change especially relevant. Flats are 57.2% of all homes in London according to the VOA stock of properties for 2025, and a large share of those are rented. In boroughs like Hackney, where 81.9% of homes are flats, landlord reports are a constant part of an electrician’s work. See our Hackney page.

Questions to ask your electrician

1. Which version of BS 7671 is this work designed to?
2. If this is an EICR, are any FI items in the report, and what further investigation do you suggest?
3. For a consumer unit change, will the certificate show 2026?
4. Which competent person scheme are you registered with? You can then check it on the scheme’s website. Replacing a consumer unit is notifiable under Part P, so either a registered person self certifies it or the council’s building control must be notified.

Our consumer unit replacement page explains how a board change runs from first visit to certificates. Prices are a quote on survey.