Evening Graham, 

I wonder if I can pick you brains on this a little more…

There are some notable exclusions in the PAS and I wondered what the reasoning for limitation was…

Domestic dwellings exceeding 200 m2 in floor area.

200m2 seems to be quite a low threshold, a fairly typical 3 bed semi can surpass this ?

It suggests at 6.5.5 (g) that batteries must not be installed in lofts etc  However PCE equipment is permitted in lofts. - do we assume the risk mitigation here is chemical rather than weight?

In Table 4 it lists BS EN IEC 62281 as the standard for Lithium, which is a transport standard…

On checking my ‘usual’ product they claim compliance to these two IEC standards amongst a few other EMC/UL/UN

IEC 63056:2020 

Secondary cells and batteries containing alkaline or other non-acid electrolytes - Safety requirements for secondary lithium cells and batteries for use in electrical energy storage systems

IEC 62619:2022 

Secondary cells and batteries containing alkaline or other non-acid electrolytes - Safety requirements for secondary lithium cells and batteries, for use in industrial applications

Neither of these seem to get a mention in the PAS at all…

The standards listed for ‘enclosures’ also dont seem to line up with anything from the likes of Eldon (Nvent Hoffmann) IEC 62208 for example

It’s a tough reed, I usually feel fairly confident with standards and interpretation etc but this seems to have reference after reference to standards, that when checked, dont seem to match up and fairly common industry standards seem absent…

Thanks

Martyn

Martyn said:

200m2 seems to be quite a low threshold, a fairly typical 3 bed semi can surpass this ?

Not nowadays. New builds in my area are tiny - around 30 m² per bedroom.

gkenyon said:

A bit of both. Interesting to consider that the battery can be a victim of a fire as well as a potential cause, so whilst weight (and perhaps the way monoblocs are seen placed hapazardly in lofts), added to chemical, and the fact that lofts have different compartmentation etc., all go in the mix.

A fair point. For me, the most obvious site would be in a walk-in attic storage space immediately below the panels. That seems to be ruled out, but not an adjacent storage room, which gives access to the loft.

I do not quite understand the 200 m² limit to the scope - the loft space of a larger house is unlikely to be any safer than one of a small house.

On a more practical note, does it matter electrically where the battery is sited please? (I had thought that it would make sense to keep all the DC bits together.)

Consider a fire in a loft, origin or cause are not important at the moment.  Now add an inverter or battery or both.

PIR insulation is optional (most are a Petrochemical derived Polystrean with is flammable)

The fire could spread from one building to the next quite easy across the roof structure especially in a terrace house or semi.

Now you have 2 fires to deal with.  


Most lofts were designed in old houses just to keep the ceiling up,  there design was not to carry weight.  There are further considerations,
Battery unit coming through the ceiling onto people below, this could be during a fire or due to the weight.
Chemical leaking out of battery unit on a failure or during a fire


Home battery technology needs to improve.  We need a BS EN to define a battery pack/unit for a dwelling.  They could also be made self extinguishing.  I have seem some with this capability already.

Chris Pearson said:

I do not quite understand the 200 m² limit to the scope - the loft space of a larger house is unlikely to be any safer than one of a small house.

No-one said it's safe in an attic in a larger house, just that there are agreed limitations for this Edition of the PAS for other reasons that I explained.

Chris Pearson said:

On a more practical note, does it matter electrically where the battery is sited please? (I had thought that it would make sense to keep all the DC bits together.)

'Electrically' is a strange word to use, because it does matter that overcurrent protection is provided very close to the battery (wherever the battery is sited), and further that we don't have wires floating around outside enclosures that have no overcurrent protection.

Yes, keeping DC together is a great idea, but in practice there are other issues that might take precedence.

It's a fine balance, because unprotected solar PV cables running through premises are also a potential concern.

Definitely an interesting debate.

gkenyon said:

Quite simply, the lack of a standard for domestic lithium batteries causes their selection to be a "non-standard approach" as far as BS 7671 is concerned.

The Abstract to BS EN IEC 63056, which is apparently under the umbrella of BS EN IEC 62619 states:

“Examples of appliances that are within the scope of this document are:

• telecommunications,

• central emergency lighting and alarm systems,

• stationary engine starting,

• photovoltaic systems,

• home (residential) energy storage systems (HESS), and

• large energy storage: on-grid/off-grid.”

So I do wonder if they are outside scope for BS7671? 

If a manufacturer supplies a complete solution, PCE, battery storage, all functional equipment monitoring and management as a ‘certified’ product, does BS7671 care or apply to the internals of said product? 

gkenyon said:

BS EN IEC 62485 series

I did look up that standard - I got to part 3 - Vehicles and then part 5 - which excludes lithium based batteries…

I might need a mortgage or at least shared in BSI soon! Ha! 

gkenyon said:

Hope this is useful ... please keep providing feedback as it will help standards develop as we use them.

Love a good debate! 

Thanks

Martyn

Still struggling with this ‘new’ forum, massive downgrade from the good ol’ days. 

Martyn said:

If a manufacturer supplies a complete solution, PCE, battery storage, all functional equipment monitoring and management as a ‘certified’ product, does BS7671 care or apply to the internals of said product? 

Just thinking more on this, and the parallel comments on LD2/LD3

Let’s assume such a product is installed outside (including 120minute separated spaces)  or in a detached building. 

Presumably, not being part of an escape route, space connected to, or close to (1m) of an escape route FD could be omitted?

In such cases would the likes of the Google Nest Protect be acceptable as a means of detection with the addition of a something like the tubes from EnviroBurst ? 

Thanks 

Martyn

Martyn said:

tubes from EnviroBurst

They would need to make something quite meaty or special to put out a fire for a battery.(house battery)  Litho battery burn like a firework even under water.  I have seen the tubes from EnviroBurst in CU/DB and they seem to work in the basic tests that people have tried.  A similar concept to putting out a fire on an oil well head. 

There are limits to what we can do with Lithium fires as has been seen from the various fires across social media and the news.

That said if we install in sealed metal cabinets and deplete oxygen on detection with something like the EnviroBurst we can limit the spread to vulnerable areas.   

I like your thinking Martyn.  Battery makers like Sun Sync need to look at their products and make them safer.  Not just for the UK market but for the global market.  Maybe they could have an indoor version and an outdoor version.  The indoor version would have more fire suppression and would cost slightly more and the outdoor version being the cheaper of the 2.  This would then cater for 2 market types.  eg small 2 bed terrace house or flat with no real outdoor space it could use.
Then the people with large dwellings or more abundance of space.  eg a large home in the suburbs.  Could use the cheaper outdoor version.

I have no affiliation for or against Sun Sync.  They were just the first name that popped into my head.  Other battery brands are available.

gkenyon said:

Chris Pearson said:

On a more practical note, does it matter electrically where the battery is sited please? (I had thought that it would make sense to keep all the DC bits together.)

'Electrically' is a strange word to use, because it does matter that overcurrent protection is provided very close to the battery (wherever the battery is sited), and further that we don't have wires floating around outside enclosures that have no overcurrent protection.

Yes, keeping DC together is a great idea, but in practice there are other issues that might take precedence.

I used the word, "electrically" to differentiate from the fire risk and whether the location is able to support the weight, etc.

I had assumed that the DC equipment would be co-located to avoid the added complexity (and cost) of converting the DC to AC and back to DC again for the battery.

In my own house, the intake is in a detached garage, which feeds the house's main DB. There is a distribution circuit to a small DB on the second floor adjacent to the only bit of roof which would be suitable for PV panels. This would seem to be more than adequate for a 4 kW array.

The battery could not go next to the house's DB because it is in a passageway and leaving aside considerations of escape routes, it would take up too much space.

That leaves the garage where there is plenty of space. (However, I wouldn't be too happy if a battery fire spread to my Rolls-Royce!)

I thought that voltage drop might just be relevant, but apart from that, does it matter where a battery might be situated please?

gkenyon said:

Chris Pearson said:

On a more practical note, does it matter electrically where the battery is sited please? (I had thought that it would make sense to keep all the DC bits together.)

'Electrically' is a strange word to use, because it does matter that overcurrent protection is provided very close to the battery (wherever the battery is sited), and further that we don't have wires floating around outside enclosures that have no overcurrent protection.

Yes, keeping DC together is a great idea, but in practice there are other issues that might take precedence.

I used the word, "electrically" to differentiate from the fire risk and whether the location is able to support the weight, etc.

I had assumed that the DC equipment would be co-located to avoid the added complexity (and cost) of converting the DC to AC and back to DC again for the battery.

In my own house, the intake is in a detached garage, which feeds the house's main DB. There is a distribution circuit to a small DB on the second floor adjacent to the only bit of roof which would be suitable for PV panels. This would seem to be more than adequate for a 4 kW array.

The battery could not go next to the house's DB because it is in a passageway and leaving aside considerations of escape routes, it would take up too much space.

That leaves the garage where there is plenty of space. (However, I wouldn't be too happy if a battery fire spread to my Rolls-Royce!)

I thought that voltage drop might just be relevant, but apart from that, does it matter where a battery might be situated please?