Metal enclosure with 3rd amendment.

[stillp]

No, they have a product standard don't they?

 

[kai]

Did one consider the end of the service cable, just before the service fuse, protected by an 800 amp substation fuse, to be the root cause of the fire problems? I certainly would!

 

[JohnW2]

I can't think of anything common in a domestic situation other than a CU that be considered an assembly.

Fair enough. Thanks.

Kind Regards, John

 

[JohnW2]

No, they have a product standard don't they?

Grid switches, per se, undoubtedly do, but what about 'assemblages' of them? Perhpas more to the point, what about a collection of assorted grid modules in a grid box - switches, fuses, dimmers, indicators etc. etc. ... does that not qualify as 'an assembly'?

Kind Regards, John

 

[ericmark]

This may now have changed but it was:-

Consumer unit (may also be known as a consumer control unit or electricity control unit). A particular type of distribution board comprising a type-tested co-ordinated assembly for the control and distribution of electrical energy, principally in domestic premises, incorporating manual means of double-pole isolation on the incoming circuit(s) and an assembly of one or more fuses, circuit-breakers, residual current operated devices or signalling and other devices proven during the type-test of the assembly as suitable for such use.

As some as altered from the original you lose the type-tested which has been a problem with the wording of Part P of course if anything went wrong they would still be held libel and it was rather a lame excuse but unless amendment 3 has also changed the wording of the definitions which it may have done since competent has gone then any small alteration from standard and it's a distribution unit but not a consumer unit.

As I said before there have been metal distribution units for years but they were not classed as consumer units.

However what ever we want to do out hands are at the moment tied as although in the manufacturers catalogues they are not on the whole sale outlets shelves.

At the moment only way is to put a plastic one in a tin box. Which of course is likely to make it run even hotter.

 

[JohnW2]

As some as altered from the original you lose the type-tested which has been a problem with the wording of Part P of course if anything went wrong they would still be held libel and it was rather a lame excuse but unless amendment 3 has also changed the wording of the definitions which it may have done since competent has gone then any small alteration from standard and it's a distribution unit but not a consumer unit.

I don't think any of that is an issue as regards th new reg, since is says that it relates to:

"Within domestic (household) premises, consumer unit and similar switchgear assemblies ...

... which I reckon covers anything resembling a CU, type-tested or not, doesn't it?

Kind Regards, John

 

[ban-all-sheds]

I think it does. I think the wording is designed to stop people putting in stuff made from inflammable plastics under the guise of "It's not a CU, it's a distribution board". As in "He's not an electrician, he's a very naughty boy".

AFAIK, the type testing issue only relates to the exemption for breaking capacity of the MCBs. My understanding is that if you build a DB using breakers with a sufficiently high Icn you'll be fine.

BTW - Eric, Part P says nothing about using type tested CUs.

 

[JohnW2]

I think it does. I think the wording is designed to stop people putting in stuff made from inflammable plastics under the guise of "It's not a CU, it's a distribution board".

Yes, that would also be my feeling.

Kind Regards, John

 

[ban-all-sheds]

Actually there's nothing wrong with requiring CUs to be made of stuff which doesn't easily catch fire. But it does seem that the impression being given, or the common interpretation of the requirement, is that means metal CUs, so either the wording is misleading, or people aren't thinking and paying attention.

Or probably both.

I did have a quick look to see what are people saying on the IET forum - the main topic about it seems to be 26 pages long, and I'm afraid I did chew my own leg off to escape before I got to the end.

I also found this in another topic there, which made me chuckle:

I can give a synopsis. AMD3 compliant boards, though not required until 1 Jan 2016, are available now for purchase. Manufacturers have decided to use metal to comply with the non-combustible requirement although many claim some existing plastic ones comply.The electrical industry is divided. Many believe that all plastic fuseboards of 17th Edition AMD2 ilk and earlier will instantly catch fire the moment the Reg comes in to force. The sensible ones are just COR. Waiting until they have to buy them. Some are expecting that the AMD3 boards will be indestructible and will contain a fire, others are laughing their heads off at them (me being one).

 

[ban-all-sheds]

They don't have to be metal - just 'non-combustible'.

Not bought a copy yet. (Tempted to wait until they correct all the mistakes).

Do they define "non-combustible"? Do they really mean non-combustible, i.e. simply-will-not-catch-fire-at-any-temperature?

And does anybody know why CUs in the rest of Europe aren't in the habit of catching fire?

 

[JohnW2]

Actually there's nothing wrong with requiring CUs to be made of stuff which doesn't easily catch fire.

Of course there isn't - indeed, if anything, it's a surprise that it hasn't previously been a requirement.

But it does seem that the impression being given, or the common interpretation of the requirement, is that means metal CUs, so either the wording is misleading, or people aren't thinking and paying attention.

I think primarily the latter, not helped by what we've been told (assuming it's true), that at least a couple of major players are seemingly going to 'drop' plastic CUs. I don't think there is anything wrong with the wording of the regulation, per se, but the misinterpretation by those who are not paying proper attention is probably not helped by the fact that a Note to the reg singles out 'ferrous' metal as the only example given of a material which is deemed to be non-combustible.

As I've said, my personal suspicion is that will will start seeing more 'compliant' plastic CUs showing their faces, and maybe some back-tracking on the part of any manufacturers who have already decided to 'drop' plastic CUs - and that, as a consequence, metal domestic CUs may never become very commonplace.

Kind Regards, John

 

[ban-all-sheds]

I've got one in the loft awaiting installation if/when I finally get round to rationalising everything and having an extension.






Although technically it isn't a "CU", so technically I might be a very naughty boy to use it.

 

[JohnW2]

Do they define "non-combustible"?

Nope, no definition, other than a requirement that it complies with BS EN 61439-3 (does that define it?) and a note indicating that an example of a material deemed to be non-combustible is ferrous metal.

Do they really mean non-combustible, i.e. simply-will-not-catch-fire-at-any-temperature?

Obviously not, but that may be clarified in the Standard. I think that Standards often define 'non-combustible' in an manner that does not mean "will not catch fire at any temperature". Indeed, I believe that in many contexts, something which 'catches fire' but then fairly rapidly 'self-extinguishes' would be classified as 'non-combustible'.

Kind Regards, John

 

[Taylortwocities]

Interesting test shown on YouTube at http://youtu.be/hg5eZkq2KgE

Here "JW" runs a test on a typical metal CU to see the thermal effect of running up to 125amps through meter tails by adjacent holes.

It is worth a watch. I think it puts the whole thing into perspective.

 

[bernardgreen]

This video by John Ward points out a major problem with a metal CU on a TT system

https://www.youtube.com/watch?v=9JLSTjV4imA