Stand alone rcd enclosure, metal or plastic

[haptism]

Hi all; a stand alone RCD enclosure, is this classed as "similar switchgear assemblies" in regards to reg 421.1.201 and so needs to be made of metal ? Im considering that a stand alone RCD and its enclosure might have a different BS number and so might not apply to this reg ? Anyone know, thanks. Its on a TNS system btw.

 

[Ian1981]

Taken from wiring matters magazine


The phrase ‘similar switchgear assemblies’ in Regulation 421.1.201 means those assemblies used for the same fundamental application as a consumer unit. A consumer unit is defined in Part 2 of BS 7671:

‘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.’

An example of a similar switchgear assembly is a three phase distribution board that is intended to be operated by ordinary persons. This would have to have isolation that interrupts the three incoming line conductors and the neutral, rather than just double-pole isolation as mentioned in the above definition.

So I would say a plastic enclosure for just an rcd stand alone is the same as a double pole isolator as used by the DNO is not applicable to the regulation.
I know the DNO isolator is outside the scope of bs 7671 but you get my point

 

[polo1]

Due to all the confusion around when Amd 3 came into force, I just started using metal enclosures in the circumstances you describe. An increase in costs, true, but they are generally better/more robust when terminating say 10mm T&E.

 

[telectrix]

@ Ian1981... I know the DNO isolator is outside the scope of bs 7671 but you get my point

but is it? may have been fitted by DNO, but if it's after the meter then it's part of the installation and should by covered by BS7671.

 

[haptism]

Due to all the confusion around when Amd 3 came into force, I just started using metal enclosures in the circumstances you describe. An increase in costs, true, but they are generally better/more robust when terminating say 10mm T&E.

Yep I might just get a metal one anyhow, but the insulated wylex ones are so cheap!
I would like to know how it stands with the regs for piece of mind

 

[haptism]

Taken from wiring matters magazine


The phrase ‘similar switchgear assemblies’ in Regulation 421.1.201 means those assemblies used for the same fundamental application as a consumer unit. A consumer unit is defined in Part 2 of BS 7671:

‘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.’

An example of a similar switchgear assembly is a three phase distribution board that is intended to be operated by ordinary persons. This would have to have isolation that interrupts the three incoming line conductors and the neutral, rather than just double-pole isolation as mentioned in the above definition.

So I would say a plastic enclosure for just an rcd stand alone is the same as a double pole isolator as used by the DNO is not applicable to the regulation.
I know the DNO isolator is outside the scope of bs 7671 but you get my point

Thanks thats throws some light on the situation but still dont tell you yay or nay !

 

[Ian1981]

@ Ian1981... I know the DNO isolator is outside the scope of bs 7671 but you get my point

but is it? may have been fitted by DNO, but if it's after the meter then it's part of the installation and should by covered by BS7671.

There's no requirement for said isolator to be in a ferrous enclosure same as the op's stand alone rcd is my point

 

[polo1]

Yep I might just get a metal one anyhow, but the insulated wylex ones are so cheap!
I would like to know how it stands with the regs for piece of mind

Yeah, I deliberately avoided answering the question. My take on it is that a non-combustible enclosure is what is intended.

 

[telectrix]

welcome to the land of confusion:

oops wrong one.

 

[Ian1981]

Thanks thats throws some light on the situation but still dont tell you yay or nay !

Says nay to me and rcd on its own isn't the same as consumer unit assemblies

 

[haptism]

Well I phone Stroma they say No, but NIC they say YES !

 

[ferg]

I would use a metal enclosure even though I would not class it as a consumer unit or similar.

If only to prevent somebody after me saying " E shouldn't av dun that it's non compliant that is!"

I wouldn't view it any differently to an FCU, RCD FCU, RCD socket etc.

 

[haptism]

[/QUOTE]I wouldn't view it any differently to an FCU, RCD FCU, RCD socket etc.[/QUOTE]

Thats my view on it too, unless it has something to do with BS numbers

 

[Octopus]

Does this mean we can no longer fit plastic RCD FCU's ?

 

[Midwest]

Yep I might just get a metal one anyhow, but the insulated wylex ones are so cheap!
I would like to know how it stands with the regs for piece of mind

When this reg came out, Wylex had a series of pics on a pdf, demonstrating their new A3 CU's. Can't found that just now, but here's their vid of their products;

Wylex - http://www.electrium.co.uk/wylex.htm

At 4.06mins you'll see they have a plastic enclosure for an S Type. I queried this topic at the time with my scheme, and their guidance, was in this situation the enclosure should be metal, commenting on Wylex standpoint, saying it doesn't say if that particular install was domestic

At the time I did ring Wylex technical about their pdf, and was told to speak to their sales, nothing to do with them? So I rang this Wylex sales manager, and asked him why they were suggesting a plastic enclosure could be used in these circumstances, his reply 'Its the lessor of two evils' . I've made a comment on the 18th draft, asking to make the definition of 'similar switchgear' clear, clear as a clear thing

Ooooppps that's 4 paragraphs again teleckky

 

[telectrix]

5 if you count the link.

 

[Midwest]

5 if you count the link.

Don't think a http link is included in the definition of a paragraph, but I'll take advice.

 

[freddo]

How about one of the nice MK 5502s 2 module enclosures, insulated but far less combustible than the usual soft plastic enclosures?