The rules on this changed recently and most consumer advice has not caught up. If you are getting battery quotes now, this is worth five minutes.
What changed
BS 7671:2018+A4:2026, the UK wiring regulations, was published on 15 Apr 2026 and introduced Chapter 57, Stationary Secondary Batteries. It is the first time the wiring standard has had rules written specifically for battery storage. It draws on PAS 63100:2024, the standard covering protection against fire for batteries in dwellings.
Since 15 Oct 2026, when the previous edition was withdrawn, new installations have had to comply.
Source: BS 7671:2018+A4:2026 and PAS 63100:2024. Checked 6 Nov 2026. Confirm the current position with your installer, who is responsible for compliance.
Lofts are out
This is the headline, because loft installations used to be common and are convenient: the space is unused, the cable run to the consumer unit is often short, and the battery is out of sight.
The problems are:
- Heat. A loft can reach extreme temperatures in summer, and heat degrades lithium batteries and increases risk.
- Ventilation. Usually poor or absent.
- Combustible material. Timbers, insulation and stored belongings, right next to the unit.
- Access. Difficult to reach for maintenance, and very difficult for the fire service in an emergency.
If an installer proposes a loft installation, ask them directly how it complies with BS 7671 Amendment 4. That is a fair question and a competent installer will have a clear answer.
Where a battery can go
The compliant options, from PAS 63100:
- Outdoors, where that is practical. On an external wall or in a purpose-built enclosure in a garden or yard, at least 1 metre from doors, windows, vents and escape routes.
- A detached garage or outbuilding. Treated as outdoors for fire safety purposes.
- An attached garage, with fire-resisting separation from the house.
- Indoors, only in the right room. Not a bedroom, hallway, landing, staircase or loft, and only with 30-minute fire separation from the rest of the house and ventilation to outside.
What matters in each case is separation from escape routes, separation from things that burn, sensible temperatures and the ability to get to it.
If you already have a battery
The new rules cover new installations If yours went in before 15 Oct 2026, it was installed to the standard in force at the time.
If yours is in a loft and you are uneasy, an electrician can assess it. Relocating is not usually a large job compared with the original installation.
What to check with your insurer
Worth a phone call before the installation rather than after:
- Tell them you are having a battery fitted, and where.
- Ask whether it affects your buildings or contents cover.
- Keep the installation certificate and the Microgeneration Certification Scheme (MCS) paperwork. If you ever need to claim, evidence that the installation was certified and compliant matters.
Most insurers are entirely relaxed about a properly installed battery. Some ask questions about siting, which is another reason to get it right first time.
Questions for the installer
- Where exactly will the battery go, and why there?
- How does that position comply with BS 7671 Amendment 4 and PAS 63100?
- What fire separation is in place, and does anything need building work?
- What is the ventilation arrangement?
- Is there an isolation point the fire service could use, and is it labelled?
- Will I get a certificate confirming compliance?
- Is the battery chemistry lithium iron phosphate or a nickel-based lithium chemistry? They behave differently in a fault and installers should be able to explain the difference plainly.
A note on proportion
Home batteries are not dangerous in normal use. Millions are installed worldwide and serious incidents are rare. The reason the standards have tightened is that the number of installations is rising quickly, and rules written for a small market are not adequate for a large one.
The point of this page is not to worry you. It is to make sure you are not the household whose battery went in the loft three weeks before the rules changed, with an installer who did not mention it.