The rules — and when they actually bite
These changes come from BS 7671:2018+A4:2026, the fourth amendment ("Amendment 4") to the 18th Edition of the IET Wiring Regulations. It was published jointly by the Institution of Engineering and Technology (IET) and the British Standards Institution (BSI).
There are two dates, and it's easy to mix them up:
| Date | What happened / happens |
|---|---|
| 15 April 2026 | Amendment 4 is published. Installers may use it immediately. |
| 15 October 2026 | The previous edition is withdrawn. From this date, new installations must comply with Amendment 4. |
Amendment 4 was published in April, but it only becomes mandatory for new work from 15 October 2026. If you are planning a new solar, battery or EV charger installation, this is the date your installer must be working to.
What's actually new
Amendment 4 is one of the most substantial updates to the 18th Edition. The changes most relevant to solar and EV households are:
- A dedicated battery chapter (Chapter 57) — for the first time, the wiring regulations have a named chapter for stationary battery storage. It sets out requirements for battery location, protection, earthing and fire safety in dwellings.
- Direct reference to PAS 63100:2024 — the fire-safety specification for home battery energy storage systems. Chapter 57 requires batteries in dwellings to be installed in line with PAS 63100, which effectively turns its "best practice" location rules into a regulatory requirement.
- Batteries treated as a generating source, not a load — protective devices must be suitable for current flowing in both directions (solar and batteries can push current back towards the consumer unit).
- Updated EV charger requirements — earthing and load-management checks before a charger is fitted.
- New sections on Power over Ethernet (Section 716) and functional earthing (Section 545) — these mostly affect smart-home wiring rather than solar, but matter if you're wiring a smart energy system.
Where you can and can't install a home battery
The biggest practical change for homeowners is where a battery can be sited. The combined effect of Chapter 57 and PAS 63100 is to rule out several locations that were previously "not ideal" but sometimes used:
| Location | Allowed? | Why |
|---|---|---|
| Loft / roof space | ❌ No | Temperature extremes, poor ventilation, fire risk to rooms below |
| Bedroom (or cupboard opening into one) | ❌ No | Sleeping occupants must not be exposed to a battery thermal event |
| Stairs, landings, hallways (escape routes) | ❌ No | A fire here would block the exit |
| Tight cupboard with no ventilation | ❌ No | Batteries need airflow to prevent heat build-up |
| Attached garage (fire-rated wall) | ✅ Yes | Separated from living areas by fire-rated construction |
| External wall (≥1 m from doors/windows/vents) | ✅ Yes | Weatherproof enclosure, away from openings |
| Utility / plant room (fire separation) | ✅ Yes | Proper ventilation and access for isolation |
| Purpose-built external enclosure | ✅ Yes | Ground-mounted in a garden or yard |
The loft ban is the change most homeowners will hear about — it was common practice in some older installs and is now explicitly ruled out. The other key point is the 1 metre external clearance from doors, windows and vents, which some existing installations did not always observe.
For most UK homes this changes little in practice: a garage, external wall or utility room is where a battery would go anyway. See how a battery changes your numbers in our battery ROI calculator, or read the full location and fire-safety rules in our dedicated guide to where a home battery can be installed.
What changes for EV chargers
The updated EV charger requirements focus on safety before the charger is even fitted:
- Load management — the installer must confirm the additional demand of an EV charger won't overload the existing consumer unit or incoming supply. In practice this often means a survey of the existing installation first, and sometimes a consumer-unit or supply upgrade.
- Correct earthing — chargers on PME (protective multiple earthing) supplies need open-PEN protection to guard against a lost neutral fault.
- Circuit protection — proper over-current and short-circuit protection, plus a safe disconnection point for maintenance.
If a quote skips the supply-and-earthing survey, treat that as a red flag. For solar-plus-EV households, work out your charging economics with our solar EV charging calculator.
Does it affect your existing system?
Amendment 4 applies to new installations and significant alterations, not retrospectively. An existing, compliant solar or battery system does not have to be moved or upgraded just because the rules changed. You only need to think about it when you add new work (a new battery, an extra circuit, a rewire).
That said, if you have an older battery in a loft or escape route, it may be worth discussing with an electrician — not because the law forces you to move it, but because the siting rules changed for good safety reasons.
How to make sure your install is compliant
Compliance ultimately sits with your installer, but there are three things you should do as the homeowner:
- Use a certified installer — an MCS-certified company for solar and battery work, or a competent electrician on a government-recognised scheme (such as NICEIC). Members of these schemes can self-certify, so you don't need separate Building Control approval.
- Ask for the certificate — a compliant job should come with an Electrical Installation Certificate (EIC) confirming the work meets BS 7671. Keep it with your paperwork.
- Check the date — from 15 October 2026, new work should be designed to Amendment 4. A good installer will already be working to it now.
Walk through the full process in our solar installation guide, and see what a compliant system should cost in best solar panels.
Planning solar, a battery or an EV charger?
Run the numbers first — then pick an installer who's already working to the new rules.
Calculate my savings →FAQ
When do the new battery and EV charger rules come into force?
The rules were published on 15 April 2026 and become mandatory for new installations from 15 October 2026, when the previous edition is withdrawn.
Do the new rules affect my existing solar panels or home battery?
Generally no. They apply to new installations and significant alterations, not retrospectively. You are not required to move or upgrade an existing, compliant system.
Where can I install a home battery under the new rules?
A garage with fire-rated separation, an external wall at least 1 metre from doors and windows, a utility room with fire separation, or a purpose-built external enclosure. Lofts, bedrooms and escape routes are no longer suitable.
How do I make sure my installation is compliant?
Use an MCS-certified installer (or a competent electrician on a recognised scheme) and ask for the Electrical Installation Certificate confirming the work meets BS 7671.
Sources: BS 7671:2018+A4:2026 (IET Wiring Regulations, 18th Edition, Amendment 4), PAS 63100:2024 (BSI), IET and BSI publications, NICEIC and MCS installer guidance. Publication and withdrawal dates verified against multiple independent UK electrical-industry sources.
Disclaimer: this guide is for general information only and is not electrical, legal or financial advice. Requirements depend on your specific property and equipment — always confirm with a qualified, registered installer before starting work.