mcb / rcbo

[sparkticus]

Also if I may expand the discussion -

How daft is 1(b) replacing a damaged cable for a single circuit only

Is there a time limit between circuits?

That one is almost a classic. Potentially you could rewire the whole house one wire at a time and not be required to notify. Over what period of time? I don't know but no wonder there is so much confusion over not only building regs but the entire notification scheme and the self certification scheme. All good ideas badly implemented it seems to me.

 

[JohnW2]

Well, a self certifying electrician is exposed to having work checked on a yearly basis.

Yes, I realise that - but it's just a (very small) statistical sample (even if it happens) and I would have expected a court to take note of the fact that the probability of any particular bit of self-certified work (notably that being considered by the court!) being 'checked' by anyone else was very low.

I tend to agree that if the work is "certified" by a self-certifying competent person than that may reduce the significance of not notifying but in today's "litigation rich" world it is not beyond the realms of possibility that it simply brings the contractor under pressure.

The world being as it is, I can't really disagree with that.

Kind Regards, John.

 

[ban-all-sheds]

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

It would be up to the person who did that to confirm beforehand that the circuit was suitable for a type C. After all, he would be legally obliged to make reasonable provision in the design and installation of it in order to protect persons operating, maintaining or altering the installations from fire or injury.

 

[JohnW2]

Also if I may expand the discussion -
How daft is 1(b) replacing a damaged cable for a single circuit only
Is there a time limit between circuits?

That one is almost a classic. Potentially you could rewire the whole house one wire at a time and not be required to notify. ....

Quite so - although I suppose one would theoretically have to be prepared to explain/'proove' why each and every one of the cables was 'damaged'! One might, of course, try arguing that exposure to environmental factors for a couple of decades (or whatever) would inevitably have done some 'damage' (the 'rule' doesn't even say 'significantly damaged'!)

Kind Regards, John.

 

[ban-all-sheds]

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.

Yup.

Schedule 4 works in a very simple way.

You start at the top, and begin reading through it. As soon as you find a match with the work you want to do you stop reading - the work is non-notifiable.

If you get to the end without finding a match then the work is notifiable.

 

[ban-all-sheds]

I take the view that replacing an MCB like-for-like is not notifiable because there are no changes in the characteristics of the related final circuit or of the consumer unit as a whole system. .

Changes in characteristics are irrelevant - you stop reading Schedule 4 before you get to the part which talks about that.

 

[Paul_C]

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.

Maybe, although the cynical side of me has to wonder whether the idea of raking in more notification fees plays a part in that process. But as John says, the local authority is supposed to follow the regulations the same as anyone else. If you or I took a piece of legislation which was full of inconsistencies but which, by literal interpretation, was quite clear, would we be excused following the precise letter of that legislation on the grounds that we were just trying to apply it in a more logical and consistent way? I very much doubt it. The response would be more likely to be along the lines of "Those are the regulations, if you don't like them petition your M.P. to get them changed" (not in precisely those words, but that would be the gist of it).

So shouldn't the local authority work to the same basic rule? If it doesn't like what the regulations actually say, it should try to get them changed.

 

[Paul_C]

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.

Quite so. We're each expected to abide by the regulations, so how can anyone do that if he's never really sure that what those regulations say is what a court will uphold them to say?

If a statute states quite clearly that "The sky is blue," then it would be a complete mockery of justice if a court could arbitrarily rule that what the government really meant to say was that the sky is green and that, therefore, the statute will be deemed to say "The sky is green."

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.

The problem is that once you start trying to place arbitrary and undefined limitations on what constitutes a replacement, how would anyone ever know where he stood?

How about replacing a single pendant light fitting with flush-mounted fitting with one lamp? How about if it had two or three? How about a bar with half a dozen spotlights?

How about replacing a BS546 5A socket outlet with a 2A version?

How about replacing a simple 1-way light switch with a dimmer?

However, whether a court would necessarily accept this as 'replacement' (rather than 'changing') is a different matter.

Couldn't those terms be considered pretty much synonymous though? If you change one fitting or device for another, then you've replaced it.

I think it might be reasonable for the average person to assume that if the regulations in schedule 4 had been intended to limit replacements to equivalent accessories, then they would say as much.

 

[Paul_C]

Also if I may expand the discussion -

How daft is 1(b) replacing a damaged cable for a single circuit only

Is there a time limit between circuits?

That one is almost a classic. Potentially you could rewire the whole house one wire at a time and not be required to notify. Over what period of time?

Those were my initial reactions when first reading that part several years ago. Does it mean that if I carelessly bang a nail through a cable to a socket I can replace that cable without notification, but that if the nail happens to hit a lighting cable on a different circuit at the same time I have to notify to replace both cables? Does it mean that even though I've damaged two different cables for two different final circuits I can replace the cable "for a single circuit only," then as soon as I've finished I can go back and replace the other cable which is also "for a single circuit only" as well, but that if I replace both together it's notifiable? Clearly that would be absolutely ridiculous.

However, I would suggest that there is another possible interpretation of 1(b). Could it be intended to exempt the replacement of any damaged cable on a final circuit, but to require notification if the feeder cable to a sub-distribution board is damaged? In other words, if the damaged cable itself feeds more than one final circuit, then the replacement becomes notifiable?

 

[Paul_C]

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

It would be up to the person who did that to confirm beforehand that the circuit was suitable for a type C. After all, he would be legally obliged to make reasonable provision in the design and installation of it in order to protect persons operating, maintaining or altering the installations from fire or injury.

No argument about that, but the question was whether such a replacement is notifiable or not. I would say that under the exemption specified in 1(a) it is not.

 

[JohnW2]

Those were my initial reactions when first reading that part several years ago. .... However, I would suggest that there is another possible interpretation of 1(b). Could it be intended to exempt the replacement of any damaged cable on a final circuit, but to require notification if the feeder cable to a sub-distribution board is damaged?

Interesting point. I'd never thought of that but, as you say, it is one possible interpretation - i.e. what it was 'meant' to say was "replacing a damaged cable which is supplying only a single final circuit".

Kind Regards, John.

 

[JohnW2]

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.

The problem is that once you start trying to place arbitrary and undefined limitations on what constitutes a replacement, how would anyone ever know where he stood?
How about ....

Agreed, but if the legislation is to have any value at all, it has to somehow address that. Although you go on to suggest that "change" and "replace" are "pretty much synonymous", I don't think you really mean that I think you would probably see a problem if someone 'replaced' an RCD with a main switch, or a 6A MCB with a 32A one, wouldn't you? Attempting to list all of the possibilities would obvioulsy be impractical and futile - maybe they could use some phrase like the "which doesn't (maybe 'adversely') alter the characteristics of the circuit", similar to that which they have used in other parts of the Schedule?

Kind Regards, John.

 

[Paul_C]

I think you would probably see a problem if someone 'replaced' an RCD with a main switch, or a 6A MCB with a 32A one, wouldn't you?

Well, obviously there might be an electrical problem with that (notwithstanding that the first one might be perfectly acceptable if there is no specific requirement for the RCD to be there). But from the purely regulatory standpoint of schedule 4 of the building regulations, I think the exemption from notification in 1(a) could still be said to apply (although obviously replacing a 6A MCB with a 32A one if the cables were not suitable etc. would fall foul of the general Part P requirement of "reasonable provision" for safety).

Attempting to list all of the possibilities would obvioulsy be impractical and futile - maybe they could use some phrase like the "which doesn't (maybe 'adversely') alter the characteristics of the circuit", similar to that which they have used in other parts of the Schedule?

Which has to raise the question: If that is what was really intended, why was such a clause not included in 1(a) as it was in 1(c) & (d) ?

That aside though, at the practical level, one has to question how anyone who is not competent enough to be doing the work in the first place could be expected to know whether his changes would affect (adversely or otherwise) the circuit protective measures, current-carrying capability of the cables, and so on.

In the case of 1(d), for example, if somebody understands enough to realize that his work of installing additional thermal insulation will affect the cable's current-carrying capacity, then surely he understands enough to do the work safely without it being notified anyway? Or, conversely, if he doesn't understand that the work planned will affect how much current the cable can carry safely, how would he realize that 1(d) requires that work to be notified?

 

[JohnW2]

Well, obviously there might be an electrical problem with that .... But from the purely regulatory standpoint of schedule 4 of the building regulations, I think the exemption from notification in 1(a) could still be said to apply ....

If (as it does) the regulatory system incorporates the provision for some things to be 'notifiable' and some not, then would one not expect that things which (as you agree) 'might present an electrical problem' would fall into the 'notifiable' category?

That aside though, at the practical level, one has to question how anyone who is not competent enough to be doing the work in the first place could be expected to know whether his changes would affect (adversely or otherwise) the circuit protective measures, current-carrying capability of the cables, and so on.

That's obviously the problem, and the reason why the legislation attempts (very poorly) to specify what things can be done without notification (presumably those things which they feel does not require the sort of knowledge to which you refer). However, as we know, and are discussing, it just isn't working.

I guess what 'DIYers' ought to be thankful for is that legislation has not simply 'outlawed' all DIY electrical work (and maybe even regulated the supply of 'wiring' products) - since that would have been the easiest legislation to draft and, if they so wished, probably much easier to police.

Kind Regards, John.

 

[sparkticus]

Doh!!! My son just arrived. He does most of our domestic work. I showed him this forum discussion, he read it, looked at me and said

but we don't notify MCB to RCBO changes. Anyway we've only done a couple of them because most of the time we install them as a function of changing the CU where we do notify

After taking a deep breath, I said "but what about the discussion we had with the LABCs at the techtalk meeting and I thought we were notifying"

He said "but I never agreed with them anyway because that's not what is called for in the regs - the LABC just make it up as they go along"

My daughter (who is 28 ) patronisingly patted me on the head and said "don't worry daddy, you can't be expected to know everything"

Oh well, just a few years to retirement!!