Musings on Amd. 3 DPC and flammability of consumer units

[Selfmade]

Amd. 3 DPC, Regulation 421.1.6 states "Materials used for the construction of enclosures of electrical equipment shall comply with the resistance to heat and fire requirements in an appropriate product standard", which set me to thinking;

Should the problem of plastic consumer unit flammability not be addressed in the relevant product standard for consumer units rather than in the wiring regulations? And

How are we supposed to know if an enclosure "compl[ies] with the resistance to heat and fire requirements in an appropriate product standard" other than by checking that the manufacturer states that it complies with the standard, which we do anyway? (Other than by trying to set fire to it ourselves of course!)

Personally I feel far more comfortable fitting metal consumer units, but getting people to pay for them is another matter. And surely if a product complies with a relevant BS or BS EN we should, at least legally, be able to rely on this?

Any thoughts would be interesting...

 

[Octopus]

Not all plastics go up in flames, so I anticipate a rush of technical "releases" from the manufacturers stating that they are compliant!

 

[Andy78]

The next amendment publishes in Jan and comes into effect next July. I believe the changes regarding combustible materials in consumer units do not come into effect until Jan 2016 however... presumably to give manufacturers time to catch up/redseign/shift old stock etc.

Don't ask me for a reference because I can't recall where I read it though ... lol

EDIT: Here it is on the IET site

http://electrical.------.org/books/amendment-no3/index.cfm

 

[Darkwood]

The plastics used in CU's are self extinguising already and consumer unit codes of standards already have been in practice many years for those who manufacturer them, this is more down to DIY set-ups where a plastic enclosure with dinrail mounts are bought and used for this purpose, I can purchase any kind of enclosure with a slotted cover for modular din rail mounted electrics, because of this the regulation has been brought in to address the issue that some will not have compliant enclosures and its to be confirmed.

 

[Selfmade]

Interesting replies folks, thanks. Darkwood - I wish I shared your confidence - but have a look at this article: Electrical Products - Fired-up over consumer units .

 

[Darkwood]

I stand corrected then selfmade as far as i was aware the 2011 BS EN standards were adequate but your source reliably informs that this is not the case and standards need to be tightened ..... quote from your link-

Plastic Consumer Units in the UK have to be constructed in accordance with BS EN 60439 (replaced in 2011 by BS EN 61438). The plastic enclosures have to withstand 660°C glow wire product tests. The opinion of the author is that this test is not sufficient to ensure the safety of the occupiers in properties where plastic consumer units are installed.The data previously detailing fires that have originated within consumer units in the London area, resulting from various types of defective electrical connections, shows an increase in these life-threatening fires.
The plastics used in the construction of consumer unit enclosures should therefore be more resistant to ignition from an internal defective electrical connection. In addition, the product should be constructed to ensure that any localised heating within the consumer unit should be contained within the product.

Dam you Self' thats twice Ive been wrong on here now .... :willy_nilly:

PS ... my post is correct but it seems that the bar is set too low for compliance and needs to be changed.

 

[Andy78]

Great post Selfmade.... very informative article

The main points I gleaned from that article were (reading between the lines at points):

• There has been an increase in house fires starting in consumer units.
• Lots of these seem to stem from loose connections on main neutral terminals
• One cause for this is poorly trained installers either not realising the importance of tightening the neutral as much as any other connection, or not having experience in how tight a connection should be.
• Another cause is the fall in standards on terminal bars in consumer units
• We should change the regs to minimise the chance of these fires getting beyond the consumer unit as we obviously can't change anything else to stop them.

Closing the barn door after the horse has bolted ?

 

[Selfmade]

quote from your link-

Plastic Consumer Units in the UK have to be constructed in accordance with BS EN 60439 (replaced in 2011 by BS EN 61438). The plastic enclosures have to withstand 660°C glow wire product tests.

…and the worst thing is, four of the five plastics tested ignited at 550°C, suggesting the CUs wouldn't even meet the already inadequate standard they claimed to.

Dam you Self' thats twice Ive been wrong on here now ....

:willy_nilly:

Woops sorry! Had the odd embarrassing moment on here myself, but the manufacturer's silence on this doesn't help.

Great post Selfmade.... very informative article

Thanks!

Closing the barn door after the horse has bolted ?

I quite agree that it would be far better if CUs had two terminal screws like some used to etc etc, and if installers did their jobs properly. But connections can still work loose over time (hence we don't hide them away in walls), and I can't help thinking that to argue against making enclosures fire resistant (I'm not sure if that's what you are suggesting) because they are not the ultimate source of the problem is like saying we shouldn't earth metal enclosures because the live parts really should be insulated. Or that buildings should not be designed to stop the spread of fire because it's better to avoid the fires starting in the first place.

I think the next worst thing after the lives being put at risk, is the fact that the BSi, who jointly develop the wiring regs, is trying to dump all the responsibility on us through regulation 421.1.6, rather than improving BS EN 61438 (consumer units), and taking steps to verify compliance.

 

[Engineer54]

I stand corrected then selfmade as far as i was aware the 2011 BS EN standards were adequate but your source reliably informs that this is not the case and standards need to be tightened ..... quote from your link-

Hold on there,.....Who are ''Electrical Products'' and what their role in life, because to be honest i've never heard of them??

Whenever i see/read articles like this, i want to know who wrote them, who pays their salaries, what is the authors or his company/clients reasoning behind publishing such an article?? And if they start chucking statistics out there i want to know how, where and who was this statistical data collected.

Now the standard in place at the moment is also a EN standard which means it is accepted by the EU and the likes of Germany and other high standard based countries, which if this article is correct is very worrying to say the least!!

 

[Selfmade]

Hold on there,.....Who are ''Electrical Products'' and what their role in life, because to be honest i've never heard of them??

Whenever i see/read articles like this, i want to know who wrote them, who pays their salaries, what is the authors or his company/clients reasoning behind publishing such an article?? And if they start chucking statistics out there i want to know how, where and who was this statistical data collected.

Now the standard in place at the moment is also a EN standard which means it is accepted by the EU and the likes of Germany and other high standard based countries, which if this article is correct is very worrying to say the least!!

You raise an important point regarding reliability of sources. I have found no information about 'Electrical Products' beyond what is contained on their own website. However in the Summer 2012 issue of 'Switched On' magazine by the Electrical Safety Council, here http://www.----------------------------/mediafile/100015990/Switched-On-25.pdf, you can find an article which confirms most of the material facts in the EP article, albeit with somewhat more emphasis on the quality of installation work and other consumer unit design issues. As far as I can tell most or all of the original research/data collection was done by the London Fire Service. The author of the EP article is stated as Nick Carey, and a short biography is included, but I haven't personally attempted to verify any of this information. A number of other internet sources discuss this issue.

I can think of possible motives for both overstating and understating risk of particular products. But there are also many people genuinely concerned about safety. Personally I am inclined to err on the side of caution whenever concerns are raised about the safety of any product. I don't doubt that the majority of EN standards are very high, but this doesn't mean they can never get anything wrong, or improve anything.

 

[alanl]

This has been done to death on the IET website forum. Do a search, and you will see the meaning of flammable and non-flammable, and the standards applied.
It has been found that some CU's do not meet current standards, although claiming to be. That is not the fault of the Installer, who is relying on the Manufacturers claims when he buys things.
Basically, there will be no requirement to fit metal CUs, junctions boxes etc - what about pattress boxes?
They are all enclosures, so focussing on CUs is only a small part of the scope of the requirements.
How about plastic conduit? Is thta classed as an 'enclosure?

In the Professional Electrician comic this month, there is a spokesman from M2 saying all CU's need to be metal from next year.
He is wrong, by a long way, so it makes you think if they are saying that, what else are they wrong about?

 

[Engineer54]

It has been found that some CU's do not meet current standards, although claiming to be.

If that has been found to be the case, one has to ask why are these CU's still on sale, and why haven't those manufacturers been prosecuted by the appropriate authorities if they do not meet the current EN and BS standards??

I notice that none of these report findings ever state what manufacturers products have been part of these tests or the manufacturers that has been proven their products don't meet current standards, which to me defeats the whole point of any of these reports, everyone is still as much in the dark as they were before the report(s)....