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

Hi Martyn,

There was a public consultation, which was widely publicised including in this Forum: RE: Public Consultation: PAS 63100 Electrical installations – Protection against fire of battery energy storage systems for use in dwellings – Specification 

I'll cover the battery standards first. This is (to me at least) interesting and will perhaps cause some debate (apologies for that, but here goes ...).

• BS EN 63056 makes reference to batteries conforming to BS EN 62619
  
• BS EN 62619 as you point out covers industrial lithium batteries.
• Reg 511.1 of BS 7671 states: 'Every item of equipment shall comply with the relevant requirements of the applicable British or Harmonized Standard, appropriate to the intended use of the equipment.'
• Reg 511.2 states 'Where equipment to be used is not covered by a British or Harmonized Standard or is to be used outside the scope of its standard, the designer or other person responsible for specifying the installation shall confirm that the equipment provides at least the same degree of safety as that afforded by compliance with BS 7671. Such use shall be recorded on the appropriate electrical certification specified in Part 6.'

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. Some more standardization work is needed here ... whether that's development of a domestic battery standard, or a way of making it possible to recognize industrial lithium batteries used outside the industrial sector is of course open to question.

Similarly, if you are quoting UL or other standards not aligned with IEC standards, Reg 511.2 again effectively requires some form of statement from the designer or installer as to the safety being "no less safe than BS 7671".

Perhaps less controversial is enclosures. The standards for battery assemblies/installations in 6.2.1 of PAS 63100 are not those simply of the "enclosure", but cover installation or assembly of "batteries in enclosures". The ones quoted are assembly or installation standards for batteries in enclosures (or in the case of BS EN IEC 62485 series, in commercial/industrial situations this could also be a battery room). This would not preclude the use of BS EN 62208 enclosures ... but it would be up tot he designer of the installation to check ventilation and protection requirements in selecting an appropriate enclosure. Referencing particular BS EN IEC 62485 series is not new ... it's been referenced in the IET CoP for EESS for some time (perhaps overlooked?). BS EN IEC 62485-5 had not been published when the 2nd Edition was finalized, but I am quite certain we will see that standard referenced in the 3rd Edition which will be available very soon.

Martyn said:

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 ?

Larger premises may require more power, but also are likely to have more space to dedicate to batteries, including perhaps outdoors etc.
There are limits in 6.5.7 that may otherwise be problematic.  In future, as we learn from more implementations, I can see the standard developing.

Martyn said:

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?

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.


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

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.)

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:

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?