Fitting consumer unit vertically

[EFLImpudence]

Therefore, is it just related to getting electric shocks when operating a switch?

I assume it is nothing to do with working inside.

 

[JohnW2]

All the Parts of IEC (and BS EN) 61439 include requirements for type testing.

In that case, I'm a bit confused. If that is the case, why does BS7671 appear to single out single-phase supplies ≤100A under the control of ordinary people for its requirement for a "CU" (type-tested DB)?

Kind Regards, John

 

[stillp]

Therefore, is it just related to getting electric shocks when operating a switch?

I assume it is nothing to do with working inside.

The distinction between ordinary and skilled/instructed? It's more general than that. Many standards requires that access inside equipment is restricted to persons having suitable training/experience/supervision.

 

[stillp]

In that case, I'm a bit confused. If that is the case, why does BS7671 appear to single out single-phase supplies ≤100A under the control of ordinary people for its requirement for a "CU" (type-tested DB)?

Kind Regards, John

It's not just a type-tested DB, it's a type-tested DB intended for use by ordinary persons.

 

[JohnW2]

"Skilled or instructed persons" are considered to have training and experience such that they understand the risks associated with the use of electricity, and can take whatever measures are necessary to avoid those risks. "Ordinary persons" do not have that training/experience and therefore need to be protected.

I've always been a bit confused by that. It seems to be referring to those who 'use', not design, install or maintain, the DBs - and it's difficult to see how such a user, no matter how much training, experience and understanding they may have, can do much about the hazards that are claimed to exist if the DB they are 'using' has been so configured, modified or installed that it does not qualify as "CU". Can you perhaps explain/clarify?

Kind Regards, John

 

[EFLImpudence]

What I'm trying to determine as I've never been sure what "type testing" is.

I had presumed it relates to the product behaving itself in normal use - i.e. not melting or catching fire.


Now I am not sure how this can be limited to operation by ordinary persons.
How does it protect or prevent anything as far as ordinary persons are concerned where a DB doesn't have to?

 

[stillp]

I've always been a bit confused by that. It seems to be referring to those who 'use', not design, install or maintain, the DBs - and it's difficult to see how such a user, no matter how much training, experience and understanding they may have, can do much about the hazards that are claimed to exist if the DB they are 'using' has been so configured, modified or installed that it does not qualify as "CU". Can you perhaps explain/clarify?

Kind Regards, John

I think you're conflating two sources of your confusion! Consider for example that someone modifies a CU in such a way that the busbar shrouds cannot be fitted. An ordinary person might not recognise the increased risk of electric shock but a trained person would.
It seems self-evident that ordinary persons are not responsible for the design or maintenance of DBs of any sort.

 

[JohnW2]

It's not just a type-tested DB, it's a type-tested DB intended for use by ordinary persons.

This is confusing!

For an installation with a 230 V single phase supply rated up to 100 A which is under the control of ordinary persons, switchgear and controlgear assemblies shall either comply with BS EN 61439-3 and Regulation 432.1 [device breaking capacity] or be a consumer unit incorporating components and protective devices specified by the manufacturer complying with BS61439-3, including the conditional short-circuit test described in Annex ZB of the standard.

and

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.

The BS7671 definition of a consumer unit says nothing about it being intended for use by ordinary persons (only "principally in domestic premises"), whereas 530.3.4 says that if the installation is under the control of ordinary persons (plus the other conditions) one way of satisfying the regulation is then for the "switchgear and control gear assemblies" to consist of a consumer unit. Can you help me to understand what this all means. I thought I understood, but you are making me wonder!

Kind Regards, John

 

[stillp]

What I'm trying to determine as I've never been sure what "type testing" is.

I had presumed it relates to the product behaving itself in normal use - i.e. not melting or catching fire.

All product standards require type testing, which is the testing of a (usually small) number of samples to verify that the requirements of that standard are met. This is distinct from routine testing, which is testing of every product manufactured to ensure that some of the requirements are met - typically for electrical products this would include some form of insulation test. Then there is sample testing, in which a proportion of production is removed and tested more intensively than for routine testing.

 

[JohnW2]

I think you're conflating two sources of your confusion! Consider for example that someone modifies a CU in such a way that the busbar shrouds cannot be fitted. An ordinary person might not recognise the increased risk of electric shock but a trained person would. It seems self-evident that ordinary persons are not responsible for the design or maintenance of DBs of any sort.

Indeed - but I thought that the people who were required to be "skilled or instructed" were those 'in control of" the installation (i.e., I thought, 'users'), not designers, installers or maintainers, and, taking your example, I don't see that such a 'user' would necessarily even know about the modification of the CU/DB.

Kind Regards, John

 

[stillp]

The BS7671 definition of a consumer unit says nothing about it being intended for use by ordinary persons (only "principally in domestic premises"), whereas 530.3.4 says that if the installation is under the control of ordinary persons (plus the other conditions) one way of satisfying the regulation is then for the "switchgear and control gear assemblies" to consist of a consumer unit. Can you help me to understand what this all means.

BS 7671 requires that consumer units conform to BS EN 61439-3, which is titled "Part 3: Distribution boards intended to be operated by ordinary persons (DBO)"
An assembly cannot be said to conform to that standard unless it meets all the requirements of the standard, including the type-testing.
Does that help?

 

[stillp]

I thought that the people who were required to be "skilled or instructed" were those 'in control of" the installation (i.e., I thought, 'users'), not designers, installers or maintainers, and, taking your example, I don't see that such a 'user' would necessarily even know about the modification of the CU/DB.

If the DB (or any other part of the installation) can be modified without their knowledge, then they cannot be said to be "in control" of the installation.

 

[JohnW2]

I hope in that case that your distribution boards contain 16kA devices ..

Sorry, I missed this one amongst the flurry of much longer posts!

Is this a reference to 432.1?

Kind Regards, John

 

[JohnW2]

BS 7671 requires that consumer units conform to BS EN 61439-3, which is titled "Part 3: Distribution boards intended to be operated by ordinary persons (DBO)" An assembly cannot be said to conform to that standard unless it meets all the requirements of the standard, including the type-testing. Does that help?

Not really, I'm afraid. In fact it merely illustrates the reason for my confusion. As I read it, 530.3.4 is saying that (in the type of installations described at the start) switchgear & controlgear can EITHER consist of a "Consumer Unit" (which you say above is what 61439-3 relates to) OR must comply with 61439-3 (and reg 432.1) - which appears to be the same Standard!

Can you explain this "EITHER/OR" to me?

Kind Regards, John

 

[EFLImpudence]

The distinction between ordinary and skilled/instructed? It's more general than that. Many standards requires that access inside equipment is restricted to persons having suitable training/experience/supervision.

Consider for example that someone modifies a CU in such a way that the busbar shrouds cannot be fitted. An ordinary person might not recognise the increased risk of electric shock but a trained person would.

Are those two statements not incongruous?