New Battery Storage Safety Rules: Where You Can (and Can't) Put One Now
A new set of UK wiring rules for home batteries took effect on 15 October 2026, and they’re stricter about where a unit can physically sit than almost anyone installing a battery before that date had to deal with.
What actually changed
Amendment 4 to BS 7671, the UK wiring regulations, added a new chapter covering stationary batteries, backed by PAS 63100 on fire safety. Three rules matter most for a typical home:
- No lofts, bedrooms or escape routes. A battery can’t be sited in a loft, a bedroom, or anywhere along the route you’d use to get out of the house in a fire.
- 1m clearance outdoors. An outdoor unit needs a metre of clear space from doors, windows and vents.
- 20kWh cap per enclosure. A single battery enclosure is capped at 20kWh. A bigger system needs to be split across multiple enclosures rather than built as one large unit.
Does this apply to a battery you already have?
No. The rules aren’t retrospective, so a battery installed before 15 October 2026 doesn’t need to be moved. They do apply the moment you touch the system, though. Swapping the inverter or adding capacity to an existing setup brings the whole installation back under the new rules.
What this means if you’re getting a quote now
Ask your installer where they’re planning to put the unit, and check that answer against the three points above before you sign anything. A garage, a utility room or an external wall away from doors and windows all still work. A loft conversion or the cupboard under the stairs next to your only escape route doesn’t, whatever space happens to be going spare there.
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Frequently asked questions
Where can't I put a home battery now?
Lofts, bedrooms and anywhere along an escape route are all off-limits under rules that took effect 15 October 2026. Outdoor units also need a metre of clearance from doors, windows and vents.
Do the new rules apply to a battery I already have installed?
No, not retrospectively. They apply from the point you alter the system, such as swapping the inverter or adding capacity, not to a battery already sitting in a loft or bedroom from before 15 October 2026.
Is there a size limit on home batteries now?
Yes, 20kWh per enclosure. A home wanting more capacity than that needs it split across multiple enclosures rather than one large unit.