Commercial battery storage fire safety: the UK standards

Fire is the concern most likely to stall a commercial battery project, and much of the advice in circulation is written for homes. This page sets out the documents that actually govern a battery on a commercial or industrial site, what each one covers, and what to ask for at each stage. It explains standards; it does not replace a designer's or fire engineer's judgement for your site.

The standards map

Each row is a different job: the electrical installation, the equipment, the premises, the planning stage, and the insurance. A compliant project needs all of them, not one.

Grid connection (G98, G99, G100) is a separate set of rules, covered in the G99 timeline guide and the G100 guide.

What changed in 2026: BS 7671 Chapter 57

Until 2026 the Wiring Regulations dealt with batteries in a short group of regulations (551.8). BS 7671:2018+A4:2026, published on 15 April 2026, moved those requirements into a new Chapter 57, "Stationary secondary battery installations": the first chapter of BS 7671 written for battery storage. According to the IET's guidance on the amendment, it applies where the battery's designed purpose is to store and supply electricity to the installation, and it excludes batteries built into products covered by their own product standards, such as pluggable UPS units and emergency lighting.

The previous version of BS 7671 is withdrawn on 15 October 2026. Any commercial battery designed now should be designed to the amended standard, and it is reasonable to ask an installer to confirm that in writing. For dwellings, the IET's guidance says Chapter 57 requires batteries to be installed in accordance with PAS 63100 (regulation 570.6.7.203). For other premises PAS 63100 does not apply directly; the location and fire protection are decided through the fire risk assessment and the other references on this page.

PAS 63100 is for homes, not commercial sites

PAS 63100:2024 is BSI's specification for protection against fire of battery systems for use in dwellings, limited to dwellings of up to 200 m² floor area. It is quoted on many commercial battery websites (this one included, until it was corrected in September 2026), but its own title rules out a factory, warehouse or office. In 2024 MCS noted that PAS 63100 had no standing in UK regulations; since Amendment 4:2026, BS 7671 itself calls it up, for batteries in dwellings. If a commercial proposal names PAS 63100 as its fire standard, ask which commercial references the design actually follows. More in PAS 63100 explained.

Larger sites: the NFCC guidance

The National Fire Chiefs Council's guidance for fire and rescue services was approved in December 2025 and replaces the 2023 version. It applies to battery systems deployed in the open air with an energy capacity of 1 MWh or more using lithium batteries, which takes in many containerised commercial installations. Two of its figures shape site layouts:

• an initial minimum distance of 30 m between battery cabinets (or associated transformers and switchgear) and occupied buildings, before mitigation such as blast walls is considered;
• fire hydrants that achieve a flow rate of no less than 25 litres per second.

It is written for fire and rescue services responding to planning consultations, so on a larger site it is worth talking to the local fire and rescue service early; for 1 MWh or more, planning guidance in England encourages exactly that (see battery storage planning permission). On a constrained yard, the separation requirement can decide between a container and an indoor system, so it belongs at feasibility stage, not after the order.

The fire risk assessment, and siting

The person responsible for fire safety in non-domestic premises must assess fire risk (the Regulatory Reform (Fire Safety) Order 2005 in England and Wales, the Fire (Scotland) Act 2005 in Scotland). A battery changes that risk, so the assessment should be reviewed before installation. The questions it has to answer differ by install type:

• Containerised, outdoors: separation from buildings, boundaries and escape routes; firefighting access and water; detection and, where required, deflagration venting. The advantage is that a thermal event stays outside the occupied building. See containerised installation.
• Indoor cabinet: the room is the fire barrier, so compartmentation to the building fire strategy, ventilation for cooling and any off-gassing, and detection tied into the building alarm. See indoor cabinet installation.

Lithium-iron-phosphate (LFP) cells are generally regarded as more thermally stable than NMC chemistry, which is one reason they are the usual choice for stationary storage, but chemistry does not replace siting and detection.

What your insurer will ask

Insurers set their own conditions, and they are often the practical deciding factor. Expect questions about the chemistry, the manufacturer's test evidence, the separation from other buildings and stock, detection and any suppression, the monitoring arrangements, and who maintains the system. Share the fire risk assessment and the installer's design with your insurer before plant is ordered: a condition that arrives after installation can be expensive to meet.

Questions to ask an installer about fire safety

• Is the installation designed to BS 7671 as amended by A4:2026, including Chapter 57?
• Which parts of the IET Code of Practice does the design follow, and who signs the design off?
• Can you show conformity evidence for BS EN IEC 62933-5-2 and IEC 62619 for this exact product?
• If PAS 63100 is cited, why, given that it covers dwellings?
• For 1 MWh or more in the open air, how does the layout compare with the NFCC guidance, and has the fire and rescue service been consulted?
• Has the insurer seen the design, and what did they ask for?
• How will the fire detection and any suppression be proved at commissioning, and which records will you hand over?

The installer checklist covers the rest: registration, grid-connection experience, insurance and warranties.