AFDD in 18th 2nd Amendment

[davesparks]

Die cast in what ? OK, sloppy use of words, but "steel" is shorter to write than "ferrous metal" - I'm assuming you mean die cast iron - plastic CU cases are die cast, as are many aluminium boxes (obviously excluding ones that are folded from flat sheet), ...

I don't know what metal they are specifically but the have the feel of, and drill like, the kind of metal boxes that are often sold as just 'die cast project boxes'. I think they are usualy some aluminium/zinc/magnesium based alloy but don't know for sure.

 

[Simon47]

Aluminium is "interesting".
Having looked it up, it's classed as non-combustible as a solid - but I think we're all aware that if you do get it going, which is a lot easier in powder form, then it takes off big time (c.f. Thermite). But again, because BS7671 doesn't specify how "non-combustible" is determined (e.g. by reference to existing standards), there's no objective way of saying aluminium complies with the regulation.

But having said that, die-cast aluminium CUs would be quite nice to work with.

 

[pc1966]

Diecast aluminium can be nice to work with, but it can also easily crack if mistreated trying to put in a big hole, etc.

Realistically pressed steel sheet is the cheapest and easiest solution to making a CU fire-containing, though some plastics would also be an option (but probably more expensive).

 

[mainline]

Aluminium is "interesting".
Having looked it up, it's classed as non-combustible as a solid - but I think we're all aware that if you do get it going, which is a lot easier in powder form, then it takes off big time (c.f. Thermite). But again, because BS7671 doesn't specify how "non-combustible" is determined (e.g. by reference to existing standards), there's no objective way of saying aluminium complies with the regulation.

But having said that, die-cast aluminium CUs would be quite nice to work with.

NOTE 1: Ferrous metal, e.g. steel, is deemed to be an example

Aluminium is a non-ferrous metal


The regs point is that the enclosure be non-combustible, if a manufacture produces a consumer unit and specify that it's non-combustible then I can't see any reason for not using it.

 

[Simon47]

If they specify that it's non-combustible to the standard specified by BS7671, no problem. Now which standard does BS7671 reference

 

[mainline]

If they specify that it's non-combustible to the standard specified by BS7671, no problem. Now which standard does BS7671 reference

They also don't specify a standard for steel ones either.

 

[Simon47]

No, but they specified that its deemed to comply - therefore using steel (or any other ferrous metal) complies with the regs.

 

[mainline]

No, but they specified that its deemed to comply - therefore using steel (or any other ferrous metal) complies with the regs.

They only deem it to be an example of a non-combustible material, they don't say “steel complies”.

 

[Simon47]

The practical effect of the wording is that they say exactly that. Is there any other interpretation of "You must use X, ferrous metal is deemed to be X" other than "using ferrous metal complies with the requirement to use X" ? Since steel is a ferrous metal, then using it is deemed to comply because the note says it does - there is no scope for doubt since ferrous metal is by definition one based on iron, and steel is an alloy composed mainly of iron.

Though I suppose you could go down the rabbit hole of pointing out that they don't define what ferrous metal is ...

 

[GBDamo]

NOTE 1: Ferrous metal, e.g. steel, is deemed to be an example

Aluminium is a non-ferrous metal


The regs point is that the enclosure be non-combustible, if a manufacture produces a consumer unit and specify that it's non-combustible then I can't see any reason for not using it.

Cast Aluminium, available from screwstation.

Are these compliant?

 

[mainline]

I would say yes as long as it's deemed to be non-combustible, but that’s listed as a garage consumer unit.

According to Luceco Technical Team,
This board is fully compliant with all of the manufacturing requirements in the 18th edition of the wiring regulations.

 

[pc1966]

Realistically all of the metals used for electrical work are going to be acceptable, steel is cheapest and easy to work with. Aluminium is easier to mould in to odd shapes and has some theoretical advantages (e.g. higher strength to weight ratio, non-magnetic, higher conductivity) but cost is likely to go against it. Same for copper and brass, but knobs on the price tag.

There are some metals that would not be acceptable, most obvious is magnesium alloys as they will burn spectacularly in air if heated to even normal temperatures. Less obvious are alloys with large amounts of beryllium in them as they result in toxic dust if worked, as well as being expensive.

 

[davesparks]

Cast Aluminium, available from screwstation.

Are these compliant?

View attachment 100729

I checked the specs on them and it actually says its cast steel.

 

[pirate]

Trying to get my head round this. Chlorine trifluoride? Crikey, i don't want to meet that any time soon! However, that and an oxygen lance are unlikely bedfellows for a domestic CU. I'm presuming that what the regs are intending, though not saying, is that the material used should be non-combustible "in the normally envisaged environment in which it is installed"...I'm simply thinking that, eg in a normal house, you are unlikely to encounter a situation where conditions can exist which would cause a normally non-combustible material to go on fire, and the purpose of the enclosure is to contain any fire that may occur within the enclosure, or prevent any fire externally from gaining access to the interior of the enclosure. I can see that steel is probably the easiest and cheapest solution for many reasons. Would carbon fibre be an option as i believe it has a very high temperature melting point and doesn't actually combust? It would look really "cool" too!

 

[mainline]

I checked the specs on them and it actually says its cast steel.

You checked the wrong one.

Put 1926g in.

https://www.NoLinkingToThis/p/briti...d=337165#product_additional_details_container

 

[Simon47]

I'm presuming that what the regs are intending, though not saying, is that the material used should be non-combustible "in the normally envisaged environment in which it is installed"

Yes, I think we all assume that. But in terms of signing a certificate to say "this installation complies with BS7671 ed foo amd bar" then I don't think "we all assume" is sufficient. I'd agree that an oxygen lance or ClF3 is highly unlikely to be involved, but I'm sure some interesting cases have come up in the past - hence the adage that nothing is foolproof as fools are so inventive.
All they (the committee behind BS7671) had to do was reference an existing standard, or simply state "when heated to X˚C in a normal atmosphere" if they didn't want to use an existing standard. Had they done that then there'd be an objective test allowing the use of any material that met the specific requirements. I.e. it would be really easy - "does the material meet the laid down objective test ?", if yes then it can be used.

 

[UNG]

Yes, I think we all assume that. But in terms of signing a certificate to say "this installation complies with BS7671 ed foo amd bar" then I don't think "we all assume" is sufficient. I'd agree that an oxygen lance or ClF3 is highly unlikely to be involved, but I'm sure some interesting cases have come up in the past - hence the adage that nothing is foolproof as fools are so inventive.
All they (the committee behind BS7671) had to do was reference an existing standard, or simply state "when heated to X˚C in a normal atmosphere" if they didn't want to use an existing standard. Had they done that then there'd be an objective test allowing the use of any material that met the specific requirements. I.e. it would be really easy - "does the material meet the laid down objective test ?", if yes then it can be used.

Wouldn't that be BS EN 61439-3.

 

[Simon47]

Wouldn't that be BS EN 61439-3.

Which doesn't specify flammability requirements AFAICS.

 

[pc1966]

You checked the wrong one.

Put 1926g in.

https://www.NoLinkingToThis/p/briti...d=337165#product_additional_details_container

The BG data sheet says steel:

https://www.bgelectrical.uk/public/downloads/data-sheets/consumer-units/metal-enclosures-datasheet.pdf

 

[mainline]

The BG data sheet says steel:

https://www.bgelectrical.uk/public/downloads/data-sheets/consumer-units/metal-enclosures-datasheet.pdf

Screwfix info says for the 1926g

Specification
Brand	British General
Cable Entry Points	Top, Bottom, Side & Rear
Construction Material (Electrical)	Aluminium
Consumer Unit Type	Garage
CSU Populated/Unpopulated	Populated
Current Rating	40 A
Fixings Supplied	Fixings Not Supplied
Integrity	Non High Integrity
IP Rating	IP65

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