Which CU ? Decisions, decisions ...

[SimonH2]

In the past I've used a couple of ProElec CUs - the plastic cases aren't anything to talk about, but the pricing makes all-RCBO an economic prospect. But, they have no plans for an Amdt3 compliant version - I asked. I guess they didn't buy any metal case tooling from whoever first designed them.

Since a new CU for home is imminent, I've been pondering ... and then an email circular from Quickbits came through. "Amdt3 CUs" and their CTI RCBOs are a good price :
https://quickbit.co.uk/Electrical/consumer-units/CTI-RCBOS
view side by side with the ProElec ones and it's "spot the difference"

Different printing, different colour plastic for the toggle !

Yes I know they are "old fashioned" and "quite long" (makes space a bit tight in the CU), but other than that is there any reason to avoid them ?

But then I see Toolstation are doing Schneider RCBOs at a good price too. At least a name I've heard of, but then you guys seem to be suggesting that's not worth all that much these days, and they don't say if the CUs are Amdt3 compliant.


On a different tack, does have an opinion (yeah, I know, silly question) if a suitable enclosure (such a small cupboard lined with plasterboard) satisfies the requirements ?

 

[deadshort]

Hager all the way for me ! and no a plasterboard lined cupboard does not comply ! nice try

DS

 

[JohnW2]

... and no a plasterboard lined cupboard does not comply ! nice try

Who knows. Give or take the impossibility of anything being "non-combustible", plasterboard of adequate thickness is regarded by the Building Regs as adequate for fire containment in various other situations.

Kind Regards, John

 

[RF Lighting]

Schneider are good as are hager. They are the only brands I'd be happy with in my own house.

 

[sparkwright]

Get something decent and easy to get spares for like Hager.

 

[sparkwright]

Fitted some Schneider sockets once, what a load of rubbish they were. I think the terminal screws were prone to going round and round or something. EDIT, I think it was ceiling roses and battenholders.

Still, I expect the consumer units are much better, probably made by someone else.

Have found MEM switches and sockets to be totally inferior too, though again their consumer units etc are good (though expensive).

 

[ban-all-sheds]

Schneider are good as are hager. They are the only brands I'd be happy with in my own house.

Siemens? MEM? M-G?

 

[ban-all-sheds]

Yes I know they are "old fashioned" and "quite long" (makes space a bit tight in the CU), but other than that is there any reason to avoid them ?

//www.diynot.com/diy/search/3448311/?q=cti&o=relevance&c[node]=8

they don't say if the CUs are Amdt3 compliant.

There aren't any, because the relevant requirement in Amd3 is impossible to comply with - it simply cannot be done.

 

[RF Lighting]

Schneider are good as are hager. They are the only brands I'd be happy with in my own house.

Siemens? MEM? M-G?

I've got MEM at the moment and they are great quality, but it's become far too difficult to source parts for them these days. None of my local wholesalers stock them, and I'd steer away from Siemens for the same reason. Merlin Gerin are now all sold under the schneider brand, as are square d. My personal preference would be Schneider acti9, which is the direct replacement for the old merlin multi9 boards, which I have seen stand the test of time in some very harsh environments, and their range of devices is the best on the market.

 

[SimonH2]

... and no a plasterboard lined cupboard does not comply ! nice try

Who knows. Give or take the impossibility of anything being "non-combustible", plasterboard of adequate thickness is regarded by the Building Regs as adequate for fire containment in various other situations.

Indeed, and that's was my thinking as well.
Where I used to work they did a lot of building work as we expanded - and all the steelwork was protected by "double boarding" to give 1" of plasterboard for the required fire protection. Not "non-combustible" in a literal sense, but certainly non-combustible (and thermally insulating) enough to stop the steelwork losing it's structural integrity before everyone has a chance to get out.

they don't say if the CUs are Amdt3 compliant.

There aren't any, because the relevant requirement in Amd3 is impossible to comply with - it simply cannot be done.

Other than the strict interpretation that there is nothing that is completely non-combustible, if we take a "common sense" (pragmatic) definition that it's not combustible under conditions likely to be found in a CU in a domestic setting (and where anyone actually cares any more) - is there still anything you find "impossible" about it ?

Yes I know steel is combustible under the right conditions, as is brick and concrete (I've watched an oxygen lance being demonstrated ) - and as for the old trick of soaking Digestives in liquid oxygen . But under conditions likely to be found in a domestic setting, and long before it reaches the point where "no one cares any more", it's not. The same goes for an enclosure made of suitable materials.
On the "brick and concrete" bit - AIUI it's generally accepted that these are deemed "non combustible" for various requirements (eg mounting of heating appliances) and in the absence of any formal definition IMO it's reasonable to look to precedents in related areas (such as rules for mounting of boilers and heating appliances etc).

Or are we supposed to accept that it's "reasonable" to expect the CU to still be intact when all there is left of the house is half the walls and a load of ash ?

 

[JohnW2]

Who knows. Give or take the impossibility of anything being "non-combustible", plasterboard of adequate thickness is regarded by the Building Regs as adequate for fire containment in various other situations.

Indeed, and that's was my thinking as well. Where I used to work they did a lot of building work as we expanded - and all the steelwork was protected by "double boarding" to give 1" of plasterboard for the required fire protection. Not "non-combustible" in a literal sense, but certainly non-combustible (and thermally insulating) enough to stop the steelwork losing it's structural integrity before everyone has a chance to get out.

Exactly. Whether for containing structural steel, creating fire-resistant ceilings, 'converting' doors into fire-resistant ones or whatever, the Building Regs have always accepted an adequate thickness of plasterboard as being acceptable for 'fire containment'. Indeed, I would expect that an enclosure made out of an adequate thickness of solid wood might well provide 30-min or 1-hour 'fire resistance'.

I do see one practical problem, which relates to any fire-resistant CU (or enclosure containing a CU). All of these other scenarios we are discussing relate to barriers to slow the penetration of a ('visible') fire through the barrier from 'outside'. In the CU (or CU-containing enclosure) scenario, the fire of interest will have originated within the CU/enclosure, and so (in the absence of alarms) the occupants of the property may not become aware of the fire until after it has penetrated the barrier, thereby not really 'buying them any time'.

Kind Regards, John

 

[ban-all-sheds]

Other than the strict interpretation that there is nothing that is completely non-combustible,

That's what the regulations call for.

if we take a "common sense" (pragmatic) definition that it's not combustible under conditions likely to be found in a CU in a domestic setting (and where anyone actually cares any more) - is there still anything you find "impossible" about it ?

Indeed there is:

Allowing the existence of sloppy, imprecise and meaningless terms and requirements in an engineering-based specifications document to go unchallenged, and for the lazy and incompetent buffoons who wrote them not to have their nonsense thrown back in their faces.

 

[JohnW2]

Allowing the existence of sloppy, imprecise and meaningless terms and requirements in an engineering-based specifications document to go unchallenged, and for the lazy and incompetent buffoons who wrote them not to have their nonsense thrown back in their faces.

Indeed - and we will all have an opportunity to throw it back in their faces when the time comes for the public consultation on the next Amendment (or edition) - or, if you feel strongly enough, you could communicate your views to the IET prior to that.

stillp, if you're listening ... do you have any information (or even just vague rumours) as to when the next consultation on BS7671 is likely to happen?

Kind Regards, John

 

[SimonH2]

I do see one practical problem, ... In the CU (or CU-containing enclosure) scenario, the fire of interest will have originated within the CU/enclosure, and so (in the absence of alarms) the occupants of the property may not become aware of the fire until after it has penetrated the barrier, thereby not really 'buying them any time'.

I suspect that smoke will leak out, even if fire is contained. And assuming there is a suitable smoke detector located nearby, then that will trigger on quite small amounts of this sort of smoke - I'd have thought.
But yes, you do make a valid point. There's not much benefit to having (say) a 1/2 hour fire resistance if it delays the alarm sounding by 1/2 hour

That's what the regulations call for.

Yes, but in the real world it's fairly easy to justify not complying to the letter with something that is impossible. After all, if something were to happen, and you ended in court, there would be two defences :
1) "But the official advice on the matter specifically says that a steel enclosure is non-combustible and meets the regs - so how do you justify claiming that it doesn't comply with the regs ?"
2) "So, if we take the regs at face value, please specify a reasonably available and practical material that meets the regs" - and then demonstrate with an oxygen lance that anything they come up with isn't actually non-combustible.

Allowing the existence of sloppy, imprecise and meaningless terms and requirements in an engineering-based specifications document to go unchallenged, and for the lazy and incompetent buffoons who wrote them not to have their nonsense thrown back in their faces.

I agree, but in the meantime, there is a set of regs, in print, to which Building Control will expect compliance. For those sparkies in one of the approved bodies, I believe their membership requires compliance with the regs.
Given that I'm sure this has already been raised, and nothing has been changed - I think it's safe to assume that no official "clarification" is going to come out soon. So people either adopt a pragmatic definition of non-combustible (that is also in line with other regs where similar wording is used) - or there can be no consumer units fitted for the next few months/years by any sparky in an approved body, and the rest of us will need to put a deviation comment on our electrical certificates.

And that brings up something. If we took the regs literally as written, what do the likes of NICEIC have to say about it since it would seem to preclude their members from fitting a consumer unit at the moment ?

EDIT: Really, while I agree with you that the regs are "wrong", debating that is just being pedantic for the sake of it. It doesn't matter how much we debate what is wrong with the regs, they are there as written and I can't see that changing. So I suggest we just accept that and move on.
Yes, complain to whoever is responsible for the cockup, but just stop arguing that it's currently not possible to fit a CU in compliance with the regs. I think we all agree - but most of us agree that there is a pragmatic approach that allows the world to carry on while we wait (for a long time) for the buffoons to sort out the mess.

 

[PBC_1966]

Maybe the regs. should be amended to something more specific, such as stating that casings should be of steel no less than such-and-such thickness?