Fitting consumer unit vertically

[ban-all-sheds]

We don't really want to get into the discussion of "being a majority does not mean that you are right".

 

[JohnW2]

We don't really want to get into the discussion of "being a majority does not mean that you are right".

I'm not suggesting that we do.

As I've said repeatedly, the BS7671 definition of an "installation" is so inadequate that there are bound to be very varied opinions as to what it is meant to mean and how it should be interpreted. However, those are simply opinions, and we have no way of knowing anything about 'right' and 'wrong'.

Having said that, in practice it probably is the opinion of the majority (of electricians) which probably matters (be that opinion 'right' or 'wrong'), since they are the people who undertake EICRs and would therefore have to make a decision as to whether the devices in the CUs/DBs in my house are compliant or not!

Kind Regards, John

 

[ban-all-sheds]

FWIW (and this is not a reply to any person or post), if this is accurate http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=30732&highlight_key=y ) it is not that BS 7671 contains an exemption under some circumstances from the 16kA requirement, it is that type-tested CUs are conditionally rated at 16kA.

 

[JohnW2]

FWIW (and this is not a reply to any person or post), if this is accurate http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=30732&highlight_key=y ) it is not that BS 7671 contains an exemption under some circumstances from the 16kA requirement, it is that type-tested CUs are conditionally rated at 16kA.

Perhaps I have not been saying so i n so many words, but that's how I've always interpreted 530.3.4. In other words, I have assumed that "... 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." is a somewhat more detailed description of what you are calling a "type-tested CU". ...

[ although, of course, in BS7671-speak, "type-tested" is theoretically redundant, since "a Consumer Unit" is required to be 'type tested'. I suppose that the Part 2 definition of CU really ought to contain a reference to the conditional 16KA test. ]

In other words, under some circumstances ('single-phase etc.) 530.3.4 allows use of such a type-tested CU (which necessarily, with its devices, has passed the 16kA conditional circuit test, although the devices themselves don't have to pass a 16kA test). If those "some circumstances" do not apply, then one is presumably stuck with 432.1.

Kind Regards, John

 

[ban-all-sheds]

although, of course, in BS7671-speak, "type-tested" is theoretically redundant, since "a Consumer Unit" is required to be 'type tested'. I suppose that the Part 2 definition of CU really ought to contain a reference to the conditional 16KA test.

Surely one can have CUs which are type-tested and which genuinely have 16kA devices, and thus not need the conditional rating?

 

[JohnW2]

Surely one can have CUs which are type-tested and which genuinely have 16kA devices, and thus not need the conditional rating?

In theory, one obviously could. What I'm far less sure of is whether there are any off-the-shelf DBs sold as "Consumer Units" which contain 16A devices.

In fact, I think we probably use this phrase "type-tested" very loosely, and not necessarily always correctly - in the sense that we tend to ascribe a lot of specific meaning to it. As I think stillp recently reminded us, any 'electrical assembly' has to be "type-tested" just as, in other fields, does a car, aircraft, ladder or whatever. As I recently wrote, despite all the talking we do about "type-tested CUs", in relation to BS7671, I'm not sure that I have ever seen one for sale described as such, let alone labelled as such.

Kind Regards, John

 

[stillp]

despite all the talking we do about "type-tested CUs", in relation to BS7671, I'm not sure that I have ever seen one for sale described as such, let alone labelled as such

Yes you have. They will be described as conforming to BS EN 61439-3, which requires type testing. There is no need for the manufacturer's description to single out one of the provisions of that standard.

 

[JohnW2]

Yes you have. They will be described as conforming to BS EN 61439-3, which requires type testing.

Indeed - but, as you've pointed out, virtually anything requires 'type testing'.

There is no need for the manufacturer's description to single out one of the provisions of that standard.

Maybe not from the manufacturer's viewpoint, but those who wish to take advantage of the second option in 530.3.4 presumably need to know ... or are you perhaps saying that, if it doesn't contain 16kA devices, then it must have undergone (and passed) that conditional short-circuit test in order to conform with 61439-3?

If so, are you saying that if one obtains a CU/DB which conforms with 61439-3, without looking (or asking questions) one wouldn't know whether it contains 16kA devices, or contains lower-rated devices, but has passed the conditional test? ... or is there something I'm not understanding properly?

If the CU/DB did contain 16kA devices (and I'm not sure that I've seen one which does), then would not have to undergo the conditional 16kA short-circuit test?

Kind Regards, John

 

[EFLImpudence]

A lot (if not all) do say 61439-3 and Annex ZB plus other conditions.

Note the bottom line of this capture - although everyone has probably forgotten that bit of the thread.

I can't find any technical documentation.

 

[JohnW2]

A lot (if not all) do say 61439-3 and Annex ZB plus other conditions.

Thanks. I must say that I don't recall having noticed the 'including Annex ZB' bit in any I have looked at - but maybe that's a memory problem! As I said before, I presume this implies that the devices are <16kA, since if they were 16kA, there presumably wouldn't be a need to do a 'conditional' 16kA test. In what you posted, there is no mention of the breaking capacity of the devices - unless that is implied by the Standards cited in relation to the various devices.

Note the bottom line of this capture - although everyone has probably forgotten that bit of the thread.

That is also very interesting, and I wonder why they say it? Given that I imagine that the same devices (other than the main switch) are probably used ('horizontally') in 3-phase boards, I suspect that it's not them that result in that instruction. Is it perhaps about the IP rating of the case (since 'top surface' requirements differ from the others)? At the start of the thread I did look at the instructions for several CUs, but found none which said anything about orientation, but I may not have looked at Hager.

I suppose the other question is whether you have seen any boards described as "Consumer Units" which do contain 16kA devices?

Kind Regards, John

 

[ban-all-sheds]

That is also very interesting, and I wonder why they say it?

Maybe they only do their tests (whatever they are) in the horizontal position?

 

[stillp]

Perhaps they feel that the lid will not self-close unless the CU is horizontal?

 

[EFLImpudence]

I presume this implies that the devices are <16kA, since if they were 16kA, there presumably wouldn't be a need to do a 'conditional' 16kA test. In what you posted, there is no mention of the breaking capacity of the devices - unless that is implied by the Standards cited in relation to the various devices.

All it states is:

As above, I cannot find the technical documentation.

 

[JohnW2]

Maybe they only do their tests (whatever they are) in the horizontal position?

Yes, that is probably the most obvious explanation, and the "why?" of that could be due to the fact that so few people will want to use them vertically. In passing, I recently wrote ...

... Given that I imagine that the same devices (other than the main switch) are probably used ('horizontally') in 3-phase boards, I suspect that it's not them that result in that instruction.

On reflection, that may not be true - since if they are not 16kA devices, they are probably not used in 3-phase boards.

Kind Regards, John

 

[JohnW2]

Perhaps they feel that the lid will not self-close unless the CU is horizontal?

Yes, possibly - in fact, if you will recall, that was the one and only reservation I voiced in relation to vertical installation.

Kind Regards, John