BS EN 61439-3 - what it actually says vs what people think it says
- Thread starter SimonH2
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As I said, your aswer (to Simon's question, if that's what you're talking about) corresponds with what I have always suspected - so I guess you must be rightOH Im pretty sure mine was the most accurate answer
Kind Regards, John
I wouldn't have expected many votes because I presume that very few people have actually seen/read the Standard and so, like me, have no sensibly-based 'beliefs' about what it 'requires'.
However, as I've said, two of us have commented (I can't see that there's much to 'discuss') - mattylad seems pretty confident that it does not 'require' any of things in your list (i.e. none of the first four things in your list!) and, as I've said, that is what (despite all we hear claimed, suggested or even asserted) I have always strongly suspected is the case.
On the topic of 'the wording of the poll' (which I have essentially kept out of!), I'm a little surprised that no-one has not said anything about the potential ambiguity of "contains fire"
Kind Regards, John
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The poll wasn't so much about what the standard does say, but about what people think it says. I'm just going by the number of threads where someone has said something along the lines of "a CU must have <some attribute>".
I realise that and, as I have said (and as I suspect might also be your view), I strongly suspect that those who say "a CU must have <some attribute>" are all, or nearly all, wrong - but, not having had an opportunity to read the Standard, I just don't know what to believe - so any vote I cast would be a sheer guess.
However, I think I've made it clear how I would vote if I were 'forced' to.
Kind Regards, John
We know that, but you said that you would tell us 'the answers' when it closed - but it sounds as if you are a bit too busy at present. We will therefore wait with bated breath!
In any event, I'm still inclined to think that my suspicion, as repeatedly voiced, will prove to be correct, even though I didn't vote (for the reasons I indicated)! ...
Had you worded the question literally like that, I would probably have been equally (if not more) disinclined to vote - since it would then have been a bit ambiguous ... whilst, like you, I know what "a lot of people think it says", I suspect that they are probably all wrong
Kind Regards, John
Aha, found a few minutes ...
BS EN 61439-3:2012 is only 32 pages, getting on for 1/2 of which is title pages and "waffle". However, it is basically a set of differences/additions to BS EN 61439-1:2011 which is 148 pages. It does make it tricky following everything simply because part 1 covers just about everything for switching low voltage.
But to start with, there's definitions :
3.1.101 distribution board intended to be operated by ordinary persons DBO
ASSEMBLY used to distribute electrical energy in domestic (household) applications and other places where operation is intended by ordinary persons
Note 1 to entry Switching operations and replacing fuse-links are examples of operations intended to be carried out by normal persons.
3.1.102 type A DBO
DBO designed to accept single pole devices
Note 1 to entry In the UK, a type A DBO used principally for domestic (household) installations and having a maximum incoming unit rating of 100 A and a maximum outgoing circuit rating of 63 A, is known as a "consumer unit" or "customer distribution board".
3.1.103 type B DBO
DBO designed to accept multi-pole and/or single pole devices
It is easy to see why there is a little confusion about some of the features - there are actually conflicting statements in the standard ! In particular, there is a national deviation in place for the UK - the note explicitly says it's not mandatory.
I believe several of these features stem from Annex ZB which is informative, not normative.
A-deviation: National deviation due to regulations, the alteration of which is for the time being outside the competence of the CENELEC member. There is a note explicitly stating that "... it is the view of the Commission of the European Communities ... that compliance with A-deviations is no longer mandatory and that the free movement of products complying with such a standard should not be restricted ..." That implies that at one point compliance was mandatory - I assume the ECJ case referenced was someone complaining about unlawful interference with free movement of goods, and the court ruled that such national deviations were unenforceable.
This would (along with note 1 to 3.1.102) account for two of the features. Double pole isolation implying single phase, and 100A explicitly stated.
3.1 Additional definition
3.1.104 Customer distribution board CDB
An integrated assembly, for the control and distribution of electrical energy, principally in a household or similar premise, incorporating manual means of double-pole isolation on the incoming circuit(s), with polarity observed throughout. They are designed for use exclusively with specific protective devices on the outgoing circuits, and type-tested for use when energized through the specified 100 amp fuse.
NOTE Generally known in the UK as a Consumer unit.
Elsewhere in the standard, it is clear that polyphase boards are allowed - leaving this (non-mandatory) definition as the only imposition of single phase.
Also elsewhere in the standard, the incomer rating is limited to 250A, and individual outgoing circuits to 125A.
BS7671 says :
536.4.201 Fault current (short-circuit) ratings
...
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 ...
Refer also to BS7671 APPENDIX 14 (Informative) DETERMINATION OF PROSPECTIVE FAULT CURRENT where it says :
In domestic (household) or similar premises, where a consumer unit to BS EN 61439-3 is used and the maximum prospective fault current declared by the distributor is 16 kA, it is not necessary to measure or calculate prospective fault current at the origin of the supply.
So complying with BS EN 61439-3:2012 and 7671 you can have a 3 phase 250A/ph supply with up to 125A on any outgoing circuit. It is probable that at some point in the past, 3.1.104 above was mandatory - which would explain the 100A (3 votes) and single phase (2 votes) limitations.
However, it is understandable that a manufacturer that has products previously type tested as single phase, 100A CUs wouldn't see any benefit in spending the money to re-certify them for polyphase and 250A. Hence that is likely to remain "standard" for some time to come.
As above, 536.4.201 makes the use of a 61439-3 compliant board mandatory - but does not impose that it be a "consumer unit".
Self closing door
This got two votes, but I can find no indication whatsoever of this as a requirement. While searching, I did find an IET Wiring Matters where it was more or less stated that the door needs to enclose any plastic components (e.g. blanking modules) - but that seems to me to be more a case of the writer adding his own interpretation to what JPEL-64 had in mind than what is actually written.
Contains fire
I think most people (correctly) assumed I meant that it would contain a fire that started within it, not that it normally has a small fire in it. As above, there is absolutely no mention of this.
Something else
As I've already said, I cannot remember some of the other interesting suggestions for characteristics a CU must possess. One I can remember is a requirement for 16kA fault switching capability.
This too stems from Annex ZB, in combination with 7671 section 536.4.201 (see above) which mentions it as one way of complying :
10.11.5 Additional test
10.11.5.7 Verification of the capability of the CDB to withstand a 16 kA fault.
The following test is applied to CDB’s as covered by the definition in 3.1.104.
There is also a requirement for IP2xC
Cable entries must be (fire) sealed
Again, I cannot see a reference for this, other than maintaining appropriate IP ratings.
What there is, and it's not something that lends itself to simple summary, is a load of extra testing requirements. I really don't have the time to understand all the relevant bits of part 1 and work out just what is different.
So as far as I can make out, there really isn't any problem using any board declared by the manufacturer as complying with BS EN 61439-3:2012 - and a quick search suggests that many (most ?) 3 phase boards seem to be advertised as such. So for those of you who'd been thinking they were departing from 7671 by having a 3P board - I don't think you are.
So in summary :
100A - not a hard requirement
Single phase - ditto
- these two, if complied with merely simplify a couple of bits of 7671
16kA breaking capacity - only required if you don't calculate/measure the prospective fault current. But not exactly hard to comply with anyway
Will contain a fire - can't find any requirement
Self closing door - no
BS EN 61439-3:2012 is only 32 pages, getting on for 1/2 of which is title pages and "waffle". However, it is basically a set of differences/additions to BS EN 61439-1:2011 which is 148 pages. It does make it tricky following everything simply because part 1 covers just about everything for switching low voltage.
But to start with, there's definitions :
3.1.101 distribution board intended to be operated by ordinary persons DBO
ASSEMBLY used to distribute electrical energy in domestic (household) applications and other places where operation is intended by ordinary persons
Note 1 to entry Switching operations and replacing fuse-links are examples of operations intended to be carried out by normal persons.
3.1.102 type A DBO
DBO designed to accept single pole devices
Note 1 to entry In the UK, a type A DBO used principally for domestic (household) installations and having a maximum incoming unit rating of 100 A and a maximum outgoing circuit rating of 63 A, is known as a "consumer unit" or "customer distribution board".
3.1.103 type B DBO
DBO designed to accept multi-pole and/or single pole devices
It is easy to see why there is a little confusion about some of the features - there are actually conflicting statements in the standard ! In particular, there is a national deviation in place for the UK - the note explicitly says it's not mandatory.
I believe several of these features stem from Annex ZB which is informative, not normative.
A-deviation: National deviation due to regulations, the alteration of which is for the time being outside the competence of the CENELEC member. There is a note explicitly stating that "... it is the view of the Commission of the European Communities ... that compliance with A-deviations is no longer mandatory and that the free movement of products complying with such a standard should not be restricted ..." That implies that at one point compliance was mandatory - I assume the ECJ case referenced was someone complaining about unlawful interference with free movement of goods, and the court ruled that such national deviations were unenforceable.
This would (along with note 1 to 3.1.102) account for two of the features. Double pole isolation implying single phase, and 100A explicitly stated.
3.1 Additional definition
3.1.104 Customer distribution board CDB
An integrated assembly, for the control and distribution of electrical energy, principally in a household or similar premise, incorporating manual means of double-pole isolation on the incoming circuit(s), with polarity observed throughout. They are designed for use exclusively with specific protective devices on the outgoing circuits, and type-tested for use when energized through the specified 100 amp fuse.
NOTE Generally known in the UK as a Consumer unit.
Elsewhere in the standard, it is clear that polyphase boards are allowed - leaving this (non-mandatory) definition as the only imposition of single phase.
Also elsewhere in the standard, the incomer rating is limited to 250A, and individual outgoing circuits to 125A.
BS7671 says :
536.4.201 Fault current (short-circuit) ratings
...
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 ...
Refer also to BS7671 APPENDIX 14 (Informative) DETERMINATION OF PROSPECTIVE FAULT CURRENT where it says :
In domestic (household) or similar premises, where a consumer unit to BS EN 61439-3 is used and the maximum prospective fault current declared by the distributor is 16 kA, it is not necessary to measure or calculate prospective fault current at the origin of the supply.
So complying with BS EN 61439-3:2012 and 7671 you can have a 3 phase 250A/ph supply with up to 125A on any outgoing circuit. It is probable that at some point in the past, 3.1.104 above was mandatory - which would explain the 100A (3 votes) and single phase (2 votes) limitations.
However, it is understandable that a manufacturer that has products previously type tested as single phase, 100A CUs wouldn't see any benefit in spending the money to re-certify them for polyphase and 250A. Hence that is likely to remain "standard" for some time to come.
As above, 536.4.201 makes the use of a 61439-3 compliant board mandatory - but does not impose that it be a "consumer unit".
Self closing door
This got two votes, but I can find no indication whatsoever of this as a requirement. While searching, I did find an IET Wiring Matters where it was more or less stated that the door needs to enclose any plastic components (e.g. blanking modules) - but that seems to me to be more a case of the writer adding his own interpretation to what JPEL-64 had in mind than what is actually written.
Contains fire
I think most people (correctly) assumed I meant that it would contain a fire that started within it, not that it normally has a small fire in it. As above, there is absolutely no mention of this.
Something else
As I've already said, I cannot remember some of the other interesting suggestions for characteristics a CU must possess. One I can remember is a requirement for 16kA fault switching capability.
This too stems from Annex ZB, in combination with 7671 section 536.4.201 (see above) which mentions it as one way of complying :
10.11.5 Additional test
10.11.5.7 Verification of the capability of the CDB to withstand a 16 kA fault.
The following test is applied to CDB’s as covered by the definition in 3.1.104.
There is also a requirement for IP2xC
Cable entries must be (fire) sealed
Again, I cannot see a reference for this, other than maintaining appropriate IP ratings.
What there is, and it's not something that lends itself to simple summary, is a load of extra testing requirements. I really don't have the time to understand all the relevant bits of part 1 and work out just what is different.
So as far as I can make out, there really isn't any problem using any board declared by the manufacturer as complying with BS EN 61439-3:2012 - and a quick search suggests that many (most ?) 3 phase boards seem to be advertised as such. So for those of you who'd been thinking they were departing from 7671 by having a 3P board - I don't think you are.
So in summary :
100A - not a hard requirement
Single phase - ditto
- these two, if complied with merely simplify a couple of bits of 7671
16kA breaking capacity - only required if you don't calculate/measure the prospective fault current. But not exactly hard to comply with anyway
Will contain a fire - can't find any requirement
Self closing door - no
Many thanks, Simon. Very briefly ....
Kind Regards, John
Indeed, but the rest of that sentence reads ..
... which seems to be a bit more specific.
As you will realise, that essentially corresponds to what I had always suspected - in short, nearly all the things that some people think/believe it says are actually myths.
Kind Regards, John
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Thank you Simon, it has been a problem since I started as an electrician, that near impossible without spending a lot of money on the books to find out myths from fact, which is not helped by trade articles which are clearly designed to sell their goods not give facts.
Indeed. As stillp always used to remind us, it is theoretically possibly to access most (all?) British (and maybe other) Standards at a public library - but I have to say that, even without Covid-19, I always have had better things to do with my time that to commute to/from such a place (well over an hour round trip for me)!
Kind Regards, John
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You should not need a journey because many libraries are signed up to the British Standards On Line service.
So you log into the portal through your library website.
That said, I tried Lancashires last week and cannot find it any more.
So you log into the portal through your library website.
That said, I tried Lancashires last week and cannot find it any more.
That's what I would have thought.
However, at least in my area it seems that means just what it says (i.e. that they are 'signed up to the British Standards On Line service - which is presumably how they get access to the Standards) and it does not mean that I (or anyone else) can use that access 'on-line' via their website. Well, that's what all the 'local' (hardly the right word in my area!) libraries tell me, anyway.
I wonder if you, or anyone else reading this, has ever been able to get access to British Standards using a method such as what you suggest? If you/they have, I might try 'arguing' with some of the libraries around here!
Do individual libraries have to pay to access this material and, if so, can they still afford to? Is that perhaps an (maybe 'the') issue?
Kind Regards, John
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