AFDD in 18th 2nd Amendment

[John-SJW]

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.

https://www.NoLinkingToThis/p/wylex-nxs-25a-30ma-sp-n-type-b-afdd-rcbo/706jk

 

[timhoward]

There are two aspects to this.
1) Inspection and Testing
The installation will be inspected according to the latest regs, and the safety of the system decided according to the judgement of the person inspecting it. There is no obligation to upgrade installations for inspection purposes unless there are safety concerns.

Eventually most inspectors decide that enough time has passed since a reg change was bought in that it moves from an suggested improvement to a potential safety issue requiring action. For example TT earthing via a metal water pipe was allowed once. We wouldn't hesitate to C2 it now. Many people decide lack of RCD for sockets outside is now a C2. To my thinking it will be a good while before lack of an AFDD become a C2 items.

2) Modifications or Extensions
This is more complicated but in general if modifying a circuit or providing a new circuit, that circuit will comply with latest regulations. The overall installation shall be in a safe condition to modify or extend. (BTW any AFDD fitted should be the same manufacturer as the enclosure.)
I think we're all still working out exactly how these ideals play out in practise. There's a discussion on another thread about this at the moment.

 

[littlespark]

On your note 2, Tim, if you’re going to add an afdd because you are adding a new circuit to an existing installation, then you would need to change a plastic CU to metal for the same reason.

They are still cost- prohibitive for adding as we would change an mcb to RCBO

It will encourage Have-a-go Henry’s avoiding paying for a professional when a simple job becomes too costly

 

[timhoward]

On your note 2, Tim, if you’re going to add an afdd because you are adding a new circuit to an existing installation, then you would need to change a plastic CU to metal for the same reason.

This is where it gets interesting. I don't actually see it like that. I'm also not saying I'm definitely right, and am very interested how others approach this.

How I'm thinking -
If I was adding a lighting circuit in a dwelling, I'd need the lighting circuit to be RCD protected to meet 18th edition.
Everything about my work concerning the new circuit has to be to latest regs.
I don't currently include the enclosure it's going into in that thinking. I'm not modifying the CU, so I feel no responsibility to change it to metal or add an SPD for that matter. My only responsibility is that the installation as a whole is safe to extend, so the CU needs to be safe, no holes in it, no thermal damage, it has a cover etc.
(The exception would be if the only way to provide RCD protection was to change the CU, in which case the CU would have to meet latest regs and yes then we're into metal box and probably SPD.)
I'd better say that I would include earthing, bonding, and tail sizes in the thinking though, and would upgrade these if found wanting.

I think the same applies to AFDD's, if I was adding a sockets circuit in a building which needed one, applying the same logic as above then it should really have one. If there's no upgrade path for the CU then it's new metal CU, SPD, and all the =32A sockets circuits need AFDDs.

At least that's how I see things. Very happy to observe more discussion and think more about it though!

 

[UNG]

then you would need to change a plastic CU to metal for the same reason.

I don't ever recall the regs saying must be metal

 

[littlespark]

I don't ever recall the regs saying must be metal

non-combustible, then....

Try asbestos

 

[Simon47]

I don't ever recall the regs saying must be metal

non-combustible, then....

Try asbestos

As written, only ferrous metal is acceptable. As we well know, the reg is a pile of poo and it's hard to understand how a supposedly professional committee could have passed it - and harder still to understand how they failed to fix it in the ltest amendment.
As written, no material complies - simply because there is no material which can be said to be non-combustible without adding some qualifications. An oxygen lance can usually cut through many things we consider non-combustible. It is only the note added that says ferrous metal is deemed to comply which makes steel enclosures "compliant".
And all it needed was for them to say something along the lines of "meets text X in BS EB YYYYY" - then I reckon a fair number of non-metallic enclosures would be acceptable (like the old Wylex fuse boards)

 

[mainline]

As written, only ferrous metal is acceptable

421.1.201 Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439-3 and shall:

(i) have their enclosure manufactured from non-combustible material, or

(ii) be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12.

NOTE 1: Ferrous metal, e.g. steel, is deemed to be an example of a non-combustible material.


What are non-combustible materials?

• Non-combustible means that the material will not ignite, burn or release flammable vapors. when exposed to fire or heat. Examples of non-combustible materials include steel, masonry, ceramics and certain insulating materials (such as fiberglass or mineral wool insulation).

 

[littlespark]

What are non-combustible materials?

• Non-combustible means that the material will not ignite, burn or release flammable vapors. when exposed to fire or heat. Examples of non-combustible materials include steel, masonry, ceramics and certain insulating materials (such as fiberglass or mineral wool insulation).

Definitely not plastic.

I’d like to see a consumer unit made of ceramic or brick…

 

[mainline]

Definitely not plastic.

I’d like to see a consumer unit made of ceramic or brick…

What about Bakelite, that's a plastic

 

[littlespark]

Have you seen the time? My brain is thinking bathroom tiles.

 

[davesparks]

Eventually most inspectors decide that enough time has passed since a reg change was bought in that it moves from an suggested improvement to a potential safety issue requiring action.

No, time isn't relevant to whether it becomes an issue. Some things will never become a safety issue and other things are straight away.

For example TT earthing via a metal water pipe was allowed once. We wouldn't hesitate to C2 it now.

I would certainly hesitate, the use of a metal water pipe as an earth electrode is still allowed.

If it is no longer providing an adequate connection to earth then it would be a C2, but if the connection to earth is adequate then it may be a C3 or no code depending on who owns the pipe.

 

[timhoward]

No, time isn't relevant to whether it becomes an issue. Some things will never become a safety issue and other things are straight away.

Thanks - I can see it wasn't obvious but I was talking about what a lot of inspectors do, not intending to say it was right.
The emphasis was supposed to be the preceding bit "The installation will be inspected according to the latest regs, and the safety of the system decided according to the judgement of the person inspecting it. There is no obligation to upgrade installations for inspection purposes unless there are safety concerns."
I was trying to say that in spite of this, many people seem to decide "it's about time that was a C2". We see it time and time again on EICR's posted here.

I would certainly hesitate, the use of a metal water pipe as an earth electrode is still allowed.

Only in very specific circumstances though! I'm sure the default position is they shall not be used unless privately owned and other caveats that I'm not looking up tonight! Maybe VOELCBs would have been a better example.

 

[Simon47]

421.1.201 Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439-3 and shall:
(i) have their enclosure manufactured from non-combustible material, or
(ii) be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12.

On that there is no debate.

NOTE 1: Ferrous metal, e.g. steel, is deemed to be an example of a non-combustible material.

Which makes ferrous metals (i.e. steel) acceptable.

What are non-combustible materials?

• Non-combustible means that the material will not ignite, burn or release flammable vapors. when exposed to fire or heat. Examples of non-combustible materials include steel, masonry, ceramics and certain insulating materials (such as fiberglass or mineral wool insulation).

And here is the problem. You cannot use that definition, or any standards for combustibility ratings, as BS7671 does not reference them. As has already been said several times, all they had to do was specify it in terms of "non-combustible according to <some standard for such things>". Had they done that, then there'd be no problem - if a material meets the referenced standard then it's OK, if it doesn't then it isn't.
As I've pointed out, steel is not "non-combustible" as you can certainly get it to combust under the right conditions. I suspect at least some of the rest can also be made to combust if you try - OK, I suspect concrete and rock melt and flow rather than oxidise when an oxygen lance is aimed at them.

And that is the problem, because BS7671 does not specify what the standard for non-combustible is, there really aren't any practical materials that can be said to comply - steel doesn't. It is only the presence of note 1 that makes steel acceptable.

 

[mainline]

On that there is no debate.

Which makes ferrous metals (i.e. steel) acceptable.

And here is the problem. You cannot use that definition, or any standards for combustibility ratings, as BS7671 does not reference them. As has already been said several times, all they had to do was specify it in terms of "non-combustible according to <some standard for such things>". Had they done that, then there'd be no problem - if a material meets the referenced standard then it's OK, if it doesn't then it isn't.
As I've pointed out, steel is not "non-combustible" as you can certainly get it to combust under the right conditions. I suspect at least some of the rest can also be made to combust if you try - OK, I suspect concrete and rock melt and flow rather than oxidise when an oxygen lance is aimed at them.

And that is the problem, because BS7671 does not specify what the standard for non-combustible is, there really aren't any practical materials that can be said to comply - steel doesn't. It is only the presence of note 1 that makes steel acceptable.

There is no published definition for the term ‘non combustible’ that aligns with the intent of Regulation 421.1.201. However, as stated in Note 1 to the regulation, ferrous metal, such as steel, is deemed to be an example of a non-combustible material.


Steel will no doubt be the material usually employed in the manufacture of the enclosure or cabinet. Nevertheless, it will be open to manufacturers to offer enclosures or cabinets made from other types of material that they claim to be non-combustible within the intent of Regulation 421.1.201. In this case, however, the manufacturer would have to provide suitable evidence to support the claim of non-combustibility, and it is not presently clear what criteria would be used to judge the non-combustibility of a material other than non-ferrous metal.

Non-combustible materials include: Any material which when tested to BS 476-11:1982 (2007) does not flame nor cause any rise in temperature on either the centre (specimen) or furnace thermocouples. Products classified as non-combustible in tests following the procedures in BS 476-4:1970 (2007).

 

[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

https://www.NoLinkingToThis/p/wylex-nxs-25a-30ma-sp-n-type-b-afdd-rcbo/706jk

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 ?"