mcb / rcbo

[Paul_C]

4) would anyone regard changing an MCB for an RCBO on any circuit as altering the characteristics of that circuit?

No, not really a RCBO has the same characteristics as a MCB, in addition it also has RCD characterisitcs.

Isn't providing additional protection still altering the characteristics though? If the overcurrent-protection characteristics of the RCBO are identical to those of the MCB it replaces then of course if the circuit was satisfactory before then it can't be made "worse" by providing that additional earth-fault protection, but I would say that the characteristics have still been altered. With the MCB a current of several amps could be flowing through an earth fault with no interruption by the circuit breaker. With the RCBO, it will take only a few tens of millamps to trip it. The circuit might be better protected than it was before, but its characteristics have still been affected.

And what if a B-type MCB is replaced with a C-type RCBO?

5) would anyone regard changing an MCB for an RCBO as re-designing the related final circuit?

No, if you added a stand alone RCD for a single circuit or even a SFCU RCD would you notify that?

Same argument with regard to it affecting protective characteristics. And if you read schedule 4, there is no specific exemption for adding an RCD to an existing circuit, so I would say that it's notifiable. The FCU RCD you could claim as exempt by way of 2(c)(ii).

 

[sparkticus]

You have to read each of the sub clauses as if it were a separate item. If any one matches the work you are doing, then it's exempt from notification.

OK thanks for that, I must admit that did help since I was not reading in such absolute terms.

In electrical terms, very little. In terms of the Building Regulations, one is the provision of a consumer unit and the other is merely replacing component parts of it. Daft? Undoubtedly.

Well, two things
- you are adding an RCD function to the origin of the final circuit where non-previously existed. this may enhance or degrade the safety aspects of that circuit. there is also a possibility that a type C or D may replace an original type B (admittedly that would be technical incompetence if the load did not demand for the change) but you see my drift?

- do you agree that the acceptance that technically there is little difference between a whole replacement and altering of characteristics/component parts vs Local BCs interpretation of the building regs of schedule 4 (1a) might lead to different interpretations across the land (as we seem to be seeing reported in this thread alone) Or is there an absolute way of interpreting this specific?

 

[sparkticus]

4) would anyone regard changing an MCB for an RCBO on any circuit as altering the characteristics of that circuit?

No, not really a RCBO has the same characteristics as a MCB, in addition it also has RCD characterisitcs.

Isn't providing additional protection still altering the characteristics though?

Exactly, it is altering the characteristics in absolute terms. Also (I accept unlikely) the final circuit (now RCD protected) may be enclosed in earthed conduit supplying a dialysis unit in a bedroom. I just can't think of another example at the moment.

 

[sparkticus]

In my opinon it is when you remove the old consumer unit/fuseboard so just the cables are left and replace it with a new one

But if you change any one or more of the essential innards then you alter the characteristics. In the case of MCB to RCBO you add RCD function. Adding an RCD is notifiable.

3) what is the difference between changing a consumer unit and changing the essential characteristics of a consumer unit?

See above

But again, you are changing the characteristics and adding an RCD function.

 

[SimonH2]

Reading the last few posts it's clear that people have forgotten something ...

The original question was "is this legal", not "does the law make sense"

 

[Paul_C]

- you are adding an RCD function to the origin of the final circuit where non-previously existed. this may enhance or degrade the safety aspects of that circuit. there is also a possibility that a type C or D may replace an original type B (admittedly that would be technical incompetence if the load did not demand for the change) but you see my drift?

Agreed, and I noted the possibility of replacing a type B MCB with a type C above. So to my mind replacing an MCB (whether with another MCB or an RCBO) certainly has the potential to alter the overall protective characteristics applied to the branch circuit in question. The same argument would apply to replacing a BS3036 rewireable fuse or a BS1361 cartridge fuse with an MCB, of course.

My point is that as far as the question of the work being notifiable vs. non-notifiable is concerned, it's irrelevant, since 1(a) exempts the replacement of fixed equipment without any reference to the protective measures for the circuit. I agree that it's highly illogical and inconsistent that the work described in 1(c) & 1(d) contains references to the exemption being on the condition that the circuit's protective measures and current-carrying capacity of the cables are unaffected while 1(a) does not, but legislation in all fields is often full of such inconsistencies.

- do you agree that the acceptance that technically there is little difference between a whole replacement and altering of characteristics/component parts vs Local BCs interpretation of the building regs of schedule 4 (1a) might lead to different interpretations across the land (as we seem to be seeing reported in this thread alone)

It could well be, but as illogical as the regulations may be, local councils have no legal authority to try and impose restrictions that the legislation does not allow. If schedule 4 says it's exempt from notification, then it's exempt.

But if you change any one or more of the essential innards then you alter the characteristics. In the case of MCB to RCBO you add RCD function. Adding an RCD is notifiable.

I would say that according to schedule 4, adding an RCD as a separate item is notifiable, because there is no specific exemption for it (the case of adding one to create a fused spur excepted, as mentioned already). That's little different from adding a new MCB or RCBO to a spare way in an existing board to create a new circuit, which would be notifiable.

But by strict interpretation of 1(a), isn't removing an MCB and putting an RCBO in its place merely the replacement of existing equipment? We hear the phrase "like-for-like replacement" thrown around a lot, but schedule 4 doesn't actually contain any such specific restriction: 1(a) refers simply to "replacing any fixed electrical equipment." It imposes no condition that the new item is in any way the same as the one it replaces.

 

[Paul_C]

Reading the last few posts it's clear that people have forgotten something ...

The original question was "is this legal", not "does the law make sense"

Precisely. Legislation is full of inconsistencies and things which make little or no sense.

But as far as the original questions are concerned, I would say that the answer to both is that the jobs are non-notifiable under the exemption provided in 1(a) of schedule 4.

Although when it comes to the practicalities, even if that were not the case, how many people would actually notify and pay anything from £150 to over £400 for the "privilege" of doing such a simple replacement job, when the chances of anyone ever querying it are just about nil?

 

[sparkticus]

- do you agree that the acceptance that technically there is little difference between a whole replacement and altering of characteristics/component parts vs Local BCs interpretation of the building regs of schedule 4 (1a) might lead to different interpretations across the land (as we seem to be seeing reported in this thread alone)

It could well be, but as illogical as the regulations may be, local councils have no legal authority to try and impose restrictions that the legislation does not allow. If schedule 4 says it's exempt from notification, then it's exempt.

I accept your points but I suspect the LABCs are not consciously trying to impose anything in this case but merely interpreting an idiosyncratic document in the best way they can with reasoned logic. I suspect it is easy for any person practising common sense to come to the erroneous conclusion that if notification is required to wholly replace a consumer unit then altering the essential characteristics should be no different. In specific regard to changing an MCB for an RCBO it is not at all surprising to me that it would be confused by those without intimate electrical knowledge allowing them to reason that it is no different from that of adding an RCD and by implication notifiable. I think we see some evidence of that in this thread alone with reports of seven LABCs who interpret in such a way. From a practical point of view I completely agree with you that if an unregistered person changes an MCB for an RCBO then it is beyond reason that they would voluntarily pre-notify, pay an inspection fee and risk a re-inspection fee but looking at it from a different perspective if they first contacted their LABC for guidance (which many do) they may well be told that it is notifiable (in error) and pointed in the direction of a person/company registered for self-certification which appears to be (I am happy to say) an LABC trend when they don't want to be bothered trawling through "electrical regulations"

 

[JohnW2]

I accept your points but I suspect the LABCs are not consciously trying to impose anything in this case but merely interpreting an idiosyncratic document in the best way they can with reasoned logic.

I'm sure that is the case, but they have to work within the law, as it is.

We are simply dealing with very badly drafted legislation, and it's not hard to think of at least one way in which that may have arisen. Those employed to who draft legislation, using their skills to avoid as much ambiguity, lack of clarity and 'loopholes' as possible, will probably not understand the engineering common sense of the subject matter they're dealing with here. Conversely, the engineers who presumably advise them (and review the drafts) will often not have the same degree of those 'legislation drafting' skills. I know that they sometimes do try to acquire 'doubly-qualified' personnel, but that's probably not easy.

However, for better or for worse, everyone (even the highest court in the land) is stuck with legislation as it's written. A court may interpret law, where is is ambiguity or uncertainty, but it cannot work on the basis of what the court feels the legislation should have said - if the interpretation of what the words of the law do say is not in dispute.

I think we are all agreed that the law, as it is, makes little sense. Although essentially irrelevant (in terms of the law) we all have personal views as to what it probably should say - but, even there, I'm not totally clear as to what people think .... take yourself. You originally expressed the view that replacing an MCB is not notifiable - and I think we probably all have to agree that is what the law says. However, subsequently we have more-or-less agreed that it is not logical for 'replacement of a CU' to be notifiable, but replacement of all (or virtually all) of the contents of a CU to not be notifiable. So where would you personally draw the line? Two MCBs, 4 MCBs, MCBs + RCDs/main switch, or what?

Some of the issue is obviously the interpretation of 'replacement', and one can only speculate about a court's interpretation. Truly like-for-like is pretty clear cut, and most people would probably be happy with 'almost like-for-like' - but there presumably is a line to be drawn somewhere. In terms of replacing a MCB with an RCBO (same 'Type'), I think I tend to the view (which others have expressed) that this is, certainly in safety terms, essentially no different ('no worse') from replacing an MCB with an MCB. If the replacement device has essentially the same 'MCB characteriustics' as the original, then the additional protection afforded by the RCD functionality cannot really (except in the most bizarre of contrived hypothetical scenarios) 'do any harm' in terms of the installation's safety. However, whether a court would necessarily accept this as 'replacement' (rather than 'changing') is a different matter.

Hardly a satisfactory situation but, given that the law is so bad, sensible operation of the system probably requires the exercise of common sense.

Kind Regards, John.

 

[riveralt]

We are simply dealing with very badly drafted legislation, and it's not hard to think of at least one way in which that may have arisen. Those employed to who draft legislation, using their skills to avoid as much ambiguity, lack of clarity and 'loopholes' as possible, will probably not understand the engineering common sense of the subject matter they're dealing with here. Conversely, the engineers who presumably advise them (and review the drafts) will often not have the same degree of those 'legislation drafting' skills. Kind Regards, John.

I have had experience of working with people who draft legislation and feel they haven't got a clue. In my case it was the Crime and Disorder Act 1998, specifically relating to ASBO's and Youth Offending Teams.
I say they haven't got a clue but in relality the civil servants drafting the legislation followed a standard mantra to any of the 'what if scenarios' we raised - that mantra was 'let the courts decide'.
Clearly the same mantra has been applied for the Building Regulations including Part P.
So no matter what you, Paul_C, Sparticus, myself or anybody else contributing to this discussion says or believes no one is right or wrong because there hasn't been any case law on it.
So to Dormermike, the decision is yours - whatever you decide will be right..... unless it goes wrong after which we may here about the case law R v Dormermike. But that wont happen will it?

 

[EFLImpudence]

Take the example of a 'shower unit'. I believe this is technically classed as a 'consumer unit'.

Therefore replacement (for a new one) is notifiable, but -

What if you were to replace just the single MCB or RCD therein?
What if you were to replace the MCB and RCD?
What if you were to replace the MCB and RCD with an RCBO?

So, legally, it would seem the notifiable part is the plastic box which alters nothing.

I had such a job recently and did notify it, to be safe, as it was only a couple of pounds.
Had it been £400, or even £150, I would have had to think about it. That's it Mrs.Customer, a new shower unit, £500 please.

I hope this clears any confusion.

 

[Paul_C]

So, legally, it would seem the notifiable part is the plastic box which alters nothing.

Ah, but what if it's just the plastic box which has been damaged and you replace only that part, transferring the existing busbars, MCB's, RCD's, etc. into it? Then one could argue that the exemption in 1(c) is applicable:

1. Work consisting of—

(c) re-fixing or replacing enclosures of existing installation components, where the circuit protective measures are unaffected;

It just shows how crazy and nonsensical schedule 4 is.

 

[JohnW2]

Take the example of a 'shower unit'. I believe this is technically classed as a 'consumer unit'.

I presume so. FWIW, as far as BS7671 is concerned,a CU is a Type-tested DB.

Therefore replacement (for a new one) is notifiable, but -
What if you were to replace just the single MCB or RCD therein?
What if you were to replace the MCB and RCD?
What if you were to replace the MCB and RCD with an RCBO?
So, legally, it would seem the notifiable part is the plastic box which alters nothing.

Exactly - hence the question I just posed to sparkticus about where he personally might draw a line. Interestingly, I think that most/all of us would probably agree that replacing an RCBO with an MCB was a different issue (and therefore ought to be notifiable) but it's not totally clear how the legislation even 'gets' that one - I guess in the interpretation of what is meant by 'replacement'?

I had such a job recently and did notify it, to be safe, as it was only a couple of pounds. Had it been £400, or even £150, I would have had to think about it. That's it Mrs.Customer, a new shower unit, £500 please.

Precisely - for you, it's irrelevant - but (and bearing in mind the name and purpose of this forum) for Jo Public it's a much more relevant matter.

Kind Regards, John.

 

[sparkticus]

unless it goes wrong after which we may here about the case law R v Dormermike. But that wont happen will it?

Or perhaps "Dormermike V buildings insurance company" when insurance company try not to pay for fire damage on a technicality that a "change" was made with no LABC notification. Where said insurance company interpret schedule 4 in their favour. All of a sudden £2.50 or even £150 might not have been so bad after all.

 

[Paul_C]

Take the example of a 'shower unit'. I believe this is technically classed as a 'consumer unit'.

I presume so. FWIW, as far as BS7671 is concerned,a CU is a Type-tested DB.

That raises another issue with regard to the interpretation of schedule 4, since nowhere in the building regulations does it actually define what is meant by the term consumer unit, which appears only in 1(a) of schedule 4. Does it mean as defined by BS7671? The building regulations don't make any mention of BS7671, other than a specific reference (also in schedule 4) with regard to the definition of a special location. So there's another ambiguity.

And what if I install a new distribution board which does not meet the BS7671 definition of a consumer unit?

If it ever came to it, would it be held that "consumer unit" means as defined by BS7671, or that it also includes some other type of distribution panel?