Commercial battery fire safety: PAS 63100, siting and your insurer

Fire safety is the single concern most likely to stall a commercial battery project — and rightly so. A poorly specified lithium system is a genuine hazard, and insurers and fire authorities have tightened their scrutiny accordingly. The good news is that this is a solved engineering problem when it is designed properly from the start. Here is what “properly” means.

The standards that apply

A commercial battery storage installation is governed by a stack of real, current standards:

• BS EN 62619 — safety requirements for the lithium cells themselves.
• BS EN/IEC 62933 — safety of the battery energy storage system as a whole.
• PAS 63100:2024 — the specification for installation and fire protection of electrical energy storage systems.
• NFCC grid-scale BESS planning guidance — fire-and-rescue-service expectations for larger and grid-scale sites.

“No standards, trust us” is not an answer. A credible installer designs to these explicitly and can show you how each is met.

LFP chemistry is a big part of the answer

Almost all modern commercial stationary storage uses lithium iron phosphate (LFP) cells rather than the older nickel-manganese-cobalt (NMC) chemistry. LFP is far more thermally stable, has a much lower thermal-runaway risk, contains no cobalt, and offers a longer cycle life — at the cost of slightly lower energy density, which rarely matters for a stationary commercial system. Specifying LFP is the first and biggest fire-safety decision, and it is why NMC has largely disappeared from new UK commercial BESS.

Siting and separation

Chemistry is necessary but not sufficient; siting is where the design earns its keep. For a containerised outdoor system, that means separation distances from buildings, boundaries and escape routes, bunding, firefighting access, and where required deflagration venting — all to NFCC guidance. The great advantage of an outdoor container is that a thermal event stays outside the occupied building.

For an indoor cabinet, the room itself is the fire barrier: compartmentation to the building fire strategy, ventilation for cooling and any off-gassing, and dedicated detection tied into the building alarm. This is why we design the room, not just drop cabinets into it.

Engage the insurer before you install, not after

The most common avoidable mistake is treating fire and insurance as a post-install formality. We produce the fire risk assessment and engage your insurer — and, where needed, the fire and rescue service — before the plant is on site. Insurers are comfortable with correctly specified, standards-compliant systems; problems arise almost entirely from cheap, non-compliant kit or poor siting, both of which are choices made at design stage.

The bottom line

Commercial battery fire safety is not a reason to avoid storage — it is a reason to choose an installer who designs to PAS 63100, specifies LFP, engineers the siting, and brings your insurer along from the start. If you have heard that batteries are “too risky,” read our myths vs facts page, or send your site details and we will show you exactly how the fire strategy would work for your building.