AFDD in 18th 2nd Amendment

[Simon47]

But BS7671 does not reference BS476 either. So because something can pass a test defined in BS476 doesn't mean it meets the requirements of BS7671.
We all know what the intent of the reg is - but as currently worded, steel is effectively the only permissible material.

 

[davesparks]

We all know what the intent of the reg is - but as currently worded, steel is effectively the only permissible material.

The fact that some manufacturers are offering die-cast CUs suggests that they view metals other than steel as suitable.

 

[pc1966]

OK, I suspect concrete and rock melt and flow rather than oxidise when an oxygen lance is aimed at them.

Look up chlorine trifluoride.

In fact, let me do it for you:

Science | AAAS

www.science.org

 

[andyb]

18th 2nd amendment comes in, in Sept.
AFDDs are in it. To be fitted on socket circuits of 32A and above.
To be fitted in residential blocks of 6 floors and above, care homes and the likes.

Are these mandatory for everyone? If say you have a 17th edition CU, do you have to update to AFDD?

AFDDs integrated with an RCBO which appear the perfect fit and fix, but £150 each.


View attachment 96764

Wylex NXS 25A 30mA SP & N Type B AFDD & RCBO

Order online at Screwfix.com. Effective protection against fires started by electric serial arc faults that cannot be detected by MCBs, RCBOs or RCDs. Combined with a miniature RCBO, providing total isolation in the event of a fault being detected. FREE next day delivery available, free...

www.screwfix.com

Socket circuits not exceding 32a John.

 

[Simon47]

The fact that some manufacturers are offering die-cast CUs suggests that they view metals other than steel as suitable.

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), ...

Look up chlorine trifluoride.

No I hadn't heard of that, and no I don't intend to experiment with it So that demonstrates that without a definition of "non combustible", not even concrete or rock (which would traditionally be classed as non-combustible) can't truly be said to comply. And the answer to "is it combustible" remains the counter question "under what conditions ?"

 

[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?