Garage electrics improvement

[ericmark]

Which are the words you are looking at?

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.

 

[ericmark]

Which are the words you are looking at?

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.

 

[JohnD]

Where did you find that text?

 

[JohnW2]

Where did you find that text?

It's (the totality of) the definition of "Consumer Unit" in Part 2 of BS7671.

In this case the wording is identical in eric's BS7671:2008 as it is in the current BS7671:2018.

Kind Regards, John

 

[JohnD]

Well that's odd

I remember there was a time when a CU was needlessly specific, allowing people to install a separate distribution board or fusebox and isolator since it was not a CU, but I thought that had been corrected by widening the definition.

It was certainly earlier than 2008.

 

[ericmark]

What I have never found is some thing which says what is permitted when in the control of an ordinary person, instructed person or skilled person.

Same applies to distance for a socket from a sink.

I think the latter was in the 14th edition now removed, but this is the problem, over the years we are told things often in collage, but when requirements are removed little is said, so I am under the impression that where in charge of an ordinary person a consumer unit must be used, not a non type tested distribution unit. However not a clue where it says that, likely some HSE paperwork.

 

[JohnW2]

Well that's odd .... I remember there was a time when a CU was needlessly specific, allowing people to install a separate distribution board or fusebox and isolator since it was not a CU, but I thought that had been corrected by widening the definition.

Note that the only real relevance of BS7671's definition of "Consumer Unit" (and, I think, the issue to which eric is referring) is ...

536.4.201 Fault current (short-circuit) ratings
The relevant fault current (short-circuit) rating of the assembly should be equal to or exceed the maximum prospective fault current at the point of connection to the system.
.........
For an installation with a 230 V single-phase supply rated up to 100 A that is under the control of ordinary persons, switchgear and controlgear assemblies shall either comply with BS EN 61439-3 having a suitable fault current (short-circuit) rating for the maximum prospective fault current at the point of connection to the system or be a consumer unit incorporating components and protective devices specified by the manufacturer complying with BS EN 61439-3, including the 16kA conditional short-circuit test described in Annex ZB of the standard

Note the word "or" that I have highlighted.

Despite what eric often seems to imply, this reg is therefore does not prohibit DBs which do not qualify as "Consumer Units" (per the reg's definition) in domestic properties but, rather, is giving a 'dispensation' that, if it does qualify as a CU, then the requirements in terms of fault current ratings of the devices it contains may be relaxed (hence the common sight of 6kA devices in CUs). If it does not qualify as a CU, it is still allowed, but has to satisfy the full requirement of "The relevant fault current (short-circuit) rating of the assembly should be equal to or exceed the maximum prospective fault current at the point of connection to the system." (which, in practice, I think would probably usually mean 16kA devices).

Kind Regards, John