Batteries in plant room and 120 minute fire rated walls

[jimseng]

Just chatting through with building control and the subject of batteries came up. He suggested I need 120 minute fire ratings for the plant room if I have my solar batteries installed inside but I can't find out if this is his recommendation or if there is something written down stipulating this. Anybody have any thoughts? I don't have an outside option.

[Dillsue]

AFAIK everything to do with battery location and fire protection are all recommendations and there's nothing mandatory.  One thing you want to understand is if your insurer stipulates anything??

[jimseng]

@Dillsue Thanks. That is what I was wondering. The whole building control landscape seems pretty vague and based on opinion.

[JohnMo]

I added mine after sign off, just incase they said variation. Then did what I felt was ok. Most batteries for houses seem to be a safer rather than less safe battery technology now. 

[jimseng]

1 hour ago, JohnMo said:

Most batteries for houses seem to be a safer rather than less safe battery technology now

Tumble dryers anyone? These battery units come with fire suppression built in. 

[BotusBuild]

I'd rather have a modern battery unit in the plant room than a tumble dryer anywhere inside the house

[jimseng]

The reason I asked this question is because this line in PAS 63100:2024 does not to agree with the building inspector's statement about 120 mins:

Quote

Any indoor location in which storage batteries or storage battery enclosures are installed shall have fire resisting separation from indoor locations identified in 6.5.5 by walls, ceilings and floors with a fire performance of at least REI 30 to BS EN 13501 series (30 min to BS 476 series for load bearing capacity, integrity and insulation).

 

Edited 19 hours ago by jimseng

[kandgmitchell]

5 hours ago, jimseng said:

He suggested I need 120 minute fire ratings for the plant room if I have my solar batteries installed inside

Just ask him where in Part B this is mentioned.......

[saveasteading]

44 minutes ago, kandgmitchell said:

ask him where in Part B

It will say that fire should not be allowed to spread.  The rest is examples of how to do this. 

We can't expect the bco to know about battery technology and risk.

So you need to know the fire risk and present this to he bco.

But 120minutes may not be difficult. usually just extra plasterboard.

[ETC]

Ask him to see the Regulation. Not just the Approved Document. 30 minutes in a house is more than enough.

[Nickfromwales]

Current client has looked into this and we spoke in depth about what's "coming next" for the regs surrounding domestic battery locations.

 

Attics are apparently getting removed from the acceptable list, largely due to the logistics of fighting a fire up an attic; eg not having a fire-fighter getting into such a compromised position to fight what is a bloody horrible fire to extinguish.

 

I always design electrical systems to have multi-sensor smoke & heat detection in all plant locations, and I always run a 3-core to the garage if it's quite near to the house as an early warning of a fire in the garage, to give the occupants an opportunity to tackle it before it became fully involved. 

 

I also put "locate / test / hush" buttons, positioned strategically, where someone woken by the omni-directional wailing of the smoke detectors can press "locate". This silences every detector except the one which has been triggered, so if in plant or attic or garage etc you can go straight to the source of the smoke / fire vs searching every room in the house in a panic.

 

2 hours ago, BotusBuild said:

I'd rather have a modern battery unit in the plant room than a tumble dryer anywhere inside the house

Not many people put the TD up the attic though, lol.  

[DamonHD]

https://www.sciencedirect.com/science/article/pii/S2352152X2501312X

 

Quantitative fire likelihood assessment of battery home storage systems in comparison to general house fires in Germany and other battery related fires

[DamonHD]

PAS 63100:2024

(Electrical installations – Protection against fire of battery energy storage systems for use in dwellings – Specification)

6.5.5 Batteries shall not be installed in any of the following locations:

a) rooms in which persons are intended to sleep;

b) routes used as a means of escape that are not defined as protected escape routes, including landings, staircases and corridors;

c) corridors, shafts, stairs or lobbies of protected escape routes;

d) firefighting lobbies, shafts or staircases;

e) storage cupboards, enclosures or spaces opening into rooms in which persons are intended to sleep;

f) outdoors (ground-mounted or wall-mounted in a suitable enclosure) within 1 m of:

1) escape routes;

2) doors;

3) windows; or

4) ventilation ports.

g) voids, roof spaces or lofts;

h) within 2 m of stored flammable materials and fuel storage tanks or cylinders; and

i) cellars or basements that have no access to the outside of the building.

 

[Dillsue]

11 hours ago, DamonHD said:

https://www.sciencedirect.com/science/article/pii/S2352152X2501312X

 

Quantitative fire likelihood assessment of battery home storage systems in comparison to general house fires in Germany and other battery related fires

Highlights suggest a very low risk from home battery systems so probably not something to be too concerned about but do your own risk assessment

[SteamyTea]

5 hours ago, DamonHD said:

PAS 63100:2024

BSI PAS are technical specifications and not laws, or even minimum standards.

While I am not saying they should be ignored, and may even be specified within laws, it would be so much easier if Building Act was available to the public free of charge.

Though a quick web search did throw up this.

https://www.legislation.gov.uk/ukpga/1984/55/data.pdf

https://www.legislation.gov.uk/ukpga/1986/44/contents

https://www.legislation.gov.uk/ukpga/1989/15/contents

https://www.legislation.gov.uk/ukpga/2022/30/contents

 

So maybe government is getting a bit more open.

 

[ProDave]

I am not sure I would want batteries inside the house.  IF they do go up in flames, almost impossible to extinguish so almost certain to lead to loss of building even with a long fire protection of their room.  I think I would want them outside in a cage.

 

Only a couple of days ago a huge blaze in Glasgow building collapse and main rail station closed for days.  Started as a fire behind the counter in a vape which people tried to put out with extinguishers and failed then it took hold.  And this is just a collection of the small batteries in vape's.

 

I expect insurers to exclude battery fires soon if they don't already.  They like a get out clause.  There is a burnt out cottage near here, insurers refused to pay out because the investigation revealed the cause as a laptop computer left sitting on a bed plugged in and charging.  Presumably it set fire to the bedding.  They say that was negligence so not insured.

[kandgmitchell]

14 hours ago, ETC said:

Ask him to see the Regulation. Not just the Approved Document. 30 minutes in a house is more than enough.

The Regulation is Regulation 4 which says:

(1) Subject to paragraph (2) building work shall be carried out so that—

(a)it complies with the applicable requirements contained in Schedule 1; and

(b)in complying with any such requirement there is no failure to comply with any other such requirement, except as may be provided for in paragraphs (1C) and (1D)].

 

The Requirement in Schedule 1 is repeated in the Approved Document B and is then interpreted in detail within the document. The requirement says;

 

Internal fire spread (structure) B3.

(1) The building shall be designed and constructed so that, in the event of fire, its stability will be maintained for a reasonable period

(2) A wall common to two or more buildings shall be designed and constructed so that it adequately resists the spread of fire between those buildings. For the purposes of this sub-paragraph a house in a terrace and a semi-detached house are each to be treated as a separate building.

(3) Where reasonably necessary to inhibit the spread of fire within the building, measures shall be taken, to an extent appropriate to the size and intended use of the building, comprising either or both of the following— (a) sub-division of the building with fire-resisting construction; (b) installation of suitable automatic fire suppression systems. 

 

Paragraph (3) seems to cover it but there is no specific mention of battery systems as things haven't caught up yet. However, since 30 minutes fire resistance for houses generally is regarded as "reasonable" I think 120 minutes would be hard to justify, given that that level of protection is only required to the largest of multi-storey buildings that also have sprinkler systems installed.

[SteamyTea]

3 minutes ago, kandgmitchell said:

sprinkler systems installed.

I wonder how effective they are when a lithium battery fire starts. 

Battery fires are generally self sustaining until the fuel runs out, so getting the temperature down is the key element to tackle, a domestic sprinkler system may not deliver enough water, for long enough.

Just speculating as I don't know the ins and outs of domestic sprinkler systems.

We have a fire suppression system in our works kitchen. It is filled with ANSULEX Low pH Liquid Agent, what ever that is. Sounds like a treatment for piles.

[DamonHD]

https://nfsa.org/2025/05/05/announcing-nfsas-lithium-ion-batteries-and-fire-sprinklers-guide/

 

https://firebuyer.com/sprinkler-systems-contain-lithium-battery-fires-in-uk-homes/

Edited 2 hours ago by DamonHD

[Marvin]

People are starting to catch on (excuse the pun)

 

 

https://www.fireprotectiononline.co.uk/fire-extinguishers/lith-ex-fire-extinguishers/

[saveasteading]

1 hour ago, SteamyTea said:

generally self sustaining

Doesn't it need oxygen? If so, then a sealed enclosure, just stud and plasterboard, would soon snuff it out.

Provided there wasn't a vent for excess heat of course.... but that can be fireproof too.

 

Regardless of the rules and of insurance, I don't want my house to burn down. Homework needed.

[Russdl]

24 minutes ago, saveasteading said:

Doesn't it need oxygen?

No, they make their own. Short of submerging them they can’t be extinguished and if you remove them from the water before they’ve cooled down sufficiently they’ll be off again. 

[SteamyTea]

28 minutes ago, saveasteading said:

Doesn't it need oxygen

I don't think it needs an extra supply of oxygen as they already have the oxygen chemically bonded in the molecules.

This seems to be the problem.  Just a look at the chemistry shows the oxygen attached.

LiFePO₄, Li₄Ti₅O₁₂ or LiCoO₂.  When working at normal temperatures, the molecules stay intact, but at elevated temperatures, some of the oxygen can break loose and react with the lithium, which releases energy.  Energy is released (generally) when a molecular bond is either formed or broken.

 

  

3 minutes ago, Russdl said:

Short of submerging them they can’t be extinguished

Yes, why submerging them gets the temperature down and the reactions slow.

 

Oxygen is not the only gas that aids combustion, try fluorine, it can 'oxidise' oxygen.

https://en.wikipedia.org/wiki/Oxygen_fluoride

Edited 24 minutes ago by SteamyTea

[jimseng]

The interesting thing about much of the discussions about fires and Lithium batteries is that they never seem to refer to LiFePo4 batteries. There is the same thing going on in the marine industry where people panic at the word "Lithium" but I have yet to see an actual report of a fire being caused by a LiFePo4 installation. The famous one recently was the Northampton canal boat explosion which has been linked to the battery installation as it was an electric boat. There are pages and pages of discussions, arguments, yelling, but I can't find an actual qualified report of what caused the boat to explode, only a comment from the fire brigade who attended on the day. The same with the boat that caught fire in Torquay a couple of years ago. It had just had a battery system upgrade "therefore" it was a Lithium battery fire.

My understanding about LiFePo4 vs other chemistry is that is specifically does not produce its own oxygen and other Lithium batteries do. Cheap e-bikes etc seem to be what cause terrible house fires. Maybe I'm wrong and I keep looking for credible evidence to the contrary as I have LiFePo4 on my boat and I like to be informed. 
Anyway. I am concluding that I should be proactive about what goes on the walls of the plant room, such as pink plasterboard, heat/smoke detectors and then re approach the BCO.

Not sure what to do about the fire door though because the gap at the bottom to satisfy MVHR ventilation seems incompatible  with fire mitigation.

[saveasteading]

So a water spray at an early stage could reduce the temperature enough?

 

Or that fire extinguisher as above, but somehow automatically. Someone could sell these. The law could require them.

 

On balance, better to let the heat vent perhaps.

We are putting ours in the detached garage so the risk is less.  Maybe a polystyrene box around it and vent outdoors.

I asked about this at a recent exhibition... negligible risk he said and no special measures required.  I wonder if we can get that in writing.