Metering enclosures - is plastic OK?

jbrameld said:

We had a challenge on one project (in a hospital) where the client (after installation) declared these to be switchgear and non-compliant with the regulations as they were not metal. 

Is a hospital 'residential premises' ?

I do know that some 'safety and compliance audit' companies cover themselves by advising that, whilst BS 7671 only requires metal consumer units (and similar assemblies) to be metal, if there is a risk, there is a risk ... If it wasn't in the specification, though ...

It's definitely not a 'consumer unit' as BS 7671 has a very specific definition of this (top of page 32 in BS 7671:2018+A2:2022) ... to be a 'consumer unit' and come under 421.201, it would have to contain a multipole isolator and at least one other type-tested device.

However,  it could be argued that metering equipment in an enclosure like this could be considered 'controlgear' and therefore 'switchgear or controlgear assembly' would apply, because it's not one item of equipment in a box, but an assembly of meter and CTs and wiring. In other words, you can't just assemble this on-site according to BS 7671 (see Regulations 113.1 and 133.1.1) ... the assembly should have been 'manufactured' to an appropriate assembly standard (such as BS EN 61439 series) and there should be a DofC, or, alternatively, Regulations 133.1.2 and 133.1.3 applied, including agreement from the Client ?

gkenyon said:

Is a hospital 'residential premises' ?

They were in the days when the on-call house officer had a bedroom on the ward.

And, of course, there were the doctors' and nurses' residences, although they got a bit jumbled up at times. ;-)

More seriously, if the risk is that sleeping people may not be aware of a developing fire, even if the patients are asleep, the staff are not.

In answer to the original question, IMHO the description is not of something which switches or controls anything.

Chris Pearson said:

In answer to the original question, IMHO the description is not of something which switches or controls anything.

It's still an 'assembly' though.

gkenyon said:

, you can't just assemble this on-site according to BS 7671 (see Regulations 113.1 and 133.1.1) ... the assembly should have been 'manufactured' to an appropriate assembly standard (such as BS EN 61439 series) and there should be a DofC, or, alternatively, Regulations 133.1.2 and 133.1.3 applied, including agreement from the Client ?

hence, the above still applies. I'm open to BS EN IEC 61010 series ... or another alternative.

gkenyon said:

However,  it could be argued that metering equipment in an enclosure like this could be considered 'controlgear' and therefore 'switchgear or controlgear assembly' would apply, because it's not one item of equipment in a box, but an assembly of meter and CTs and wiring. In other words, you can't just assemble this on-site according to BS 7671 (see Regulations 113.1 and 133.1.1) ... the assembly should have been 'manufactured' to an appropriate assembly standard (such as BS EN 61439 series) and there should be a DofC, or, alternatively, Regulations 133.1.2 and 133.1.3 applied, including agreement from the Client ?

And this is where I start to struggle with what constitutes what and where an installer starts to assume a 'manufacturer' role with associated complexities, testing, approvals and costs that customers likely are not interested in entertaining.

If we expand this thought process a bit - consider a smart home installer/system integrator: They buy a large DIN rail enclosure 'product' and then several other control and monitoring 'products' such as ELV power supplies, lighting controllers, blind controllers, central control processors, meters etc. - there are thousands of such DIN rail products to choose from. Each product is likely made to it's own relevant standard.  By the act of taking a number of devices and building them into the enclosure to make an 'integrated system'/'assembly' what would be expected of that integrator?  Would each project with a slightly different assembled combination of 'products' need to be tested to ensure compliance with 61439?  That doesn't seem remotely practical.

At the other end of the scale - an electrician takes a DIN-Rail doorbell transformer and puts it on it's own into a DIN-rail box.  Are they now a manufacturer, and need to submit that assembly for testing and/or issue a DofC for it?  That doesn't seem practical either.

Is there a pragmatic solution to this conundrum?

jbrameld said:

If we expand this thought process a bit - consider a smart home installer/system integrator: They buy a large DIN rail enclosure 'product' and then several other control and monitoring 'products' such as ELV power supplies, lighting controllers, blind controllers, central control processors, meters etc. - there are thousands of such DIN rail products to choose from. Each product is likely made to it's own relevant standard.  By the act of taking a number of devices and building them into the enclosure to make an 'integrated system'/'assembly' what would be expected of that integrator?  Would each project with a slightly different assembled combination of 'products' need to be tested to ensure compliance with 61439?  That doesn't seem remotely practical

Practical or otherwise, BS 7671 is quite clear that such assemblies ought to conform to relevant standards.

One basic issue is dealing with ambient temperature inside the enclosure, and how that affects the operation of protective devices.

Another issue can be EMC.

The basic premise of "two or more conformant products must lead to a conformant product" isn't necessarily true. This is often abbreviated to:

CE+CE≠CE

Can you put 'assemblies' together and 'self-declare'? ... yes, that's entirely possible, as it's not a product that's placed on the open-market, but keeping a technical file of the design and build is important to demonstrate either:

(a) how you think you've met the requirements of standards; or

(b) how you otherwise claim you have met the 'essential requirements' of the Electrical Equipment (Safety) Regulations.

It is difficult without a clear definition of an assembly though - e.g. if I take a socket from one manufacturer, a back box from another, a grommet from the third, screws from a fourth, possibly even a telescopic stud bracket from a fifth and put them all together on site - is that an assembly? If so I'm in a lot of trouble, if not where is the line drawn?

   - Andy.

I think that we are agreed that you can select whichever devices you want from a manufacturer's catalogue in one of their distribution boards, but if you put somebody else's device in there, you become the manufacturer.

So, developing Andy's train of thought, the same might apply to a DB. Once you cut a hole in the back or side and insert a grommet or gland, have you created a new assembly? No.

AJJewsbury said:

If so I'm in a lot of trouble, if not where is the line drawn?

It seems to me that the line is rather fuzzy.

gkenyon said:

Can you put 'assemblies' together and 'self-declare'? ... yes, that's entirely possible, as it's not a product that's placed on the open-market, but keeping a technical file of the design and build is important to demonstrate either:

(a) how you think you've met the requirements of standards; or

(b) how you otherwise claim you have met the 'essential requirements' of the Electrical Equipment (Safety) Regulations.

It is certainly wise to do so, but imagine if a domestic sparks had to do that every time that he (or she) constructed an installation. Different entirely in e.g. a hospital.

If you have not placed the assembly on the market, the Electrical Equipment (Safety) Regulations 2016 do not apply:

Electrical equipment to which these Regulations apply

3.—(1) Subject to paragraph (2), these Regulations apply to electrical equipment—

(a) placed on the market on or after the commencement date; and ... [voltage range]

Yes - exaclty.

And where does our electrician fitting a doorbell transformer in a DIN-rail enclosure sit with all this?

Are they expected to maintain a technical file every time they do this, and assess the EMC performance of that 'assembly', and what the internal temperature conditions might be?

In principle, that is the idea, and exactly the same is true for folk assembling burglar alarms cameras and security systems with sensors in various places, full heating systems out of valves and pumps and controllers from various makers and so forth. For the doorbell the technical file could be as simple as a postcard size document block diagram of the system and provided a copy as part of the user instructions, but in practice is often absent.

Mike

Yes - I suspect proper compliance at this level is rather rare.

Yes - I suspect proper compliance at this level is rather rare.