BS 7671:2018+A4:2026 was published on 15 April 2026 and can be used immediately; the previous edition (Amendment 3, 2024) is withdrawn on 15 October 2026. Amendment 4 adds a chapter on stationary secondary batteries and widens the regulations' scope to cover them. Its Regulation 570.6.7.203 requires batteries in dwellings to be installed in a suitable location taking account of the manufacturer's instructions and PAS 63100, and there is a rule on when a Type B RCD is needed. Ask your installer which edition the certificate will be issued against.
Analysis · Published by SEO Dons Ltd · Updated 14 October 2026
Why this date matters to a battery buyer
BS 7671 is the British Standard for electrical installations, the document an electrician certifies their work against. Editions change by amendment, and each amendment has a period when two versions are both acceptable. For Amendment 4 that period is six months: it was published on 15 April 2026, and the earlier edition is withdrawn on 15 October 2026. From then, an installer designing a new home battery works to Amendment 4 and nothing else.
That would be a footnote for most homes, except that Amendment 4 is the first edition with a chapter dedicated to stationary secondary batteries, the technical name for the lithium units on a garage wall.
| Date | What happens |
|---|---|
| 15 April 2026 | BS 7671:2018+A4:2026 published and available for immediate use (NICEIC, EDA) |
| 15 April to 14 October 2026 | Both Amendment 4 and the 2024 edition are acceptable |
| 15 October 2026 | The 2018+A2:2022+A3:2024 edition, with its 2023 corrigendum, is withdrawn |
What the batteries chapter says
The published summaries agree on the outline:
- Scope. Regulation 110.11, which says what the Wiring Regulations apply to, now includes stationary secondary batteries for the storage and supply of electrical installations.
- A new chapter. The EDA slides and NICEIC’s webinar notes call it Chapter 57. One training provider’s article calls it Chapter 702 and mentions speculation about renumbering, and a trade-press report gives no number, so the exact numbering is worth confirming against the published text.
- Location in homes. The EDA slides give Regulation 570.6.7.203 as requiring stationary secondary batteries in dwellings to be installed in a suitable location taking account of the manufacturer’s instructions and PAS 63100.
- RCD protection. A Type B RCD is needed unless one of three conditions applies: the power conversion equipment gives at least simple separation between its AC and DC sides; simple separation is provided between that equipment and the RCD by separate windings of a transformer; or the equipment manufacturer states that a Type B RCD is not needed.
Homebuilding & Renovating’s report of 14 April gives a headline version of the change: that home batteries should not go in loft spaces or escape routes. The PAS 63100 exclusion list says the same, which is the likely source, and it is the PAS rather than a separate loft rule that the new regulation brings into the installer’s duty.
What it does not say
Three limits are worth knowing, because articles on this topic often blur them.
- It does not set numbers. The 1 m and 2 m clearances, the 30-minute fire separation and the 20, 40 and 80 kWh limits all sit in PAS 63100, not in BS 7671.
- It does not require AFDDs on battery circuits. NICEIC’s FAQ states there is no requirement in BS 7671 to include arc fault detection devices in a circuit supplying a battery energy storage system.
- It does not, on the evidence of these summaries, require existing batteries to be moved. NICEIC describes the amendment as usable for new installations, modifications, and periodic inspection and testing, and none of the summaries mention upgrading batteries already in place.
The caveat on everything above: the EDA slides and NICEIC pages are secondary summaries by trade bodies, and the regulation numbers come from the slides rather than the published standard, which is sold by the IET and BSI. An installer certifying to Amendment 4 will have the text.
What to ask for
- Which edition will my certificate be issued against? For anything signed after 15 October 2026, the answer should be Amendment 4.
- Where does the battery go, and which PAS 63100 clause makes that location acceptable? A good installer can answer in a sentence; a quote that assumes a loft or hallway is a red flag.
- How is the RCD arrangement handled? Ask which of the three conditions applies to the inverter, and where the manufacturer’s statement is.
- Will I get the PAS 63100 statement of conformity with the electrical installation certificate? The PAS suggests one. Our walk-through of the specification explains what it contains.
If a quote includes a large line item for “regulations”, ask what exactly it pays for, and compare it with two other battery storage quotes.
If you already have a battery
Nothing here makes an existing installation illegal overnight. But PAS 63100 and the new regulation make the case for a quick review if yours was installed somewhere the PAS excludes. Check where it sits against the room-by-room table, look at whether your smoke alarms are interlinked, and raise it with the installer who fitted it or your next electrician. For the wider choice of installer, the installer guide lists what to check for MCS and consumer-code membership.
Questions people ask
When does BS 7671 Amendment 4 become mandatory?
Amendment 4 was published on 15 April 2026 and can be used straight away. The previous edition, BS 7671:2018+A2:2022+A3:2024 with its 2023 corrigendum, remains current until 15 October 2026 and is withdrawn on that date, so any new design after it has to follow Amendment 4.
What does Amendment 4 say about home batteries?
It adds a new chapter on stationary secondary batteries (the Electrical Distributors' Association and NICEIC both call it Chapter 57) and widens the scope of the regulations to include batteries that store and supply electrical installations. One regulation in it, 570.6.7.203, requires batteries in dwellings to be installed in a suitable location taking account of the manufacturer's instructions and PAS 63100.
Does Amendment 4 ban batteries in lofts?
Press coverage says so, but the summaries that quote the regulation only describe it as pointing to PAS 63100, which rules out voids, roof spaces and lofts for the battery itself. Because Amendment 4 tells installers to take account of that specification, a battery in a loft is hard to justify, but check the regulation's wording with your installer.
Do I need a Type B RCD for a home battery?
According to the Electrical Distributors' Association's briefing, a Type B RCD is needed unless the power conversion equipment provides at least simple separation between its AC and DC sides, or simple separation is provided between that equipment and the RCD by separate transformer windings, or the equipment manufacturer states that a Type B RCD is not required. Most hybrid inverters come with their own statement, so ask the installer which applies.
Does my existing battery have to be changed?
Nothing in the summaries from NICEIC or the EDA says existing installations must be upgraded. NICEIC describes Amendment 4 as applying to new installations, modifications, and periodic inspection and testing. If your battery was fitted before the change, ask your installer at the next inspection whether the location still meets PAS 63100.