Connecting replacement cable, for hob circuit, into old Consumer Unit with shared RCD - 'legal' (within regulations) or not; notifiable or not?

[BobT007]

I had assumed (rightly or wrongly) that a re-connection of a cable into the consumer unit would be straightforward, with no regulations issues, as there was a hob connection there before, with 32A MCB and the shared RCD protection.

To expand a little, the original 6mm cable was however changed because of some damage, and a new 10mm cable run in its place. (So, is this a non-notifiable 'repair' ‘replacement’ ‘maintenance’ ‘addition’ or ‘alteration’ of an existing circuit to consumer unit, or a 'new circuit' to consumer unit ?!)

So,
1.
Of most interest to me, is this query 1 - I have an older plastic cover CU, using a shared RCD for the hob circuit (and oven and socket circuits) - is it okay, within regulations / 'legally' (and safe, of course), to connect the 'new'/'replacement' cable back into the existing 32A MCB where the old hob cable connection was, like for like, no other changes. Or, would this not be allowed under the current stricter regulations ?!

2. (assuming this is allowable, even if not ideal)
a)
Would this class as 'notifiable' work, according to Part P, or not? (Seems to me dependent on definition or interpretation of ‘new circuit’ I suppose vs. ‘addition/alteration/replacement/repair/maintenance’ of a circuit ??)

b)
If notifiable, then obviously qualified electrician who can self-certify it is the way to go. If not notifiable, then could anyone, in theory (not saying I would), actually connect the cable back into the consumer unit, or does any work inside consumer unit need to be done by a qualified electrician?



[I actually read the Electrical Safety P document and these are the bits that have NOT helped clarify for me the notifiable/not notifiable aspect for my case:

Notifiable: 2.5. 12(6A) “... Where work consists of (a) the installation of a new circuit; ...”

Not Notifiable: 2.7. “... additions and alterations to existing installations outside special locations, and replacements, repairs and maintenance anywhere.”]

(As I understand it, Kitchens are no longer counted as a special location.)



As always, thanks in advance for helpful advice and knowledge and suggestions.

 

[EFLImpudence]

The Building Regulations 2010

These Regulations revoke and replace the Building Regulations 2000 (S.I. 2000/2531) (“the 2000 Regulations”), and consolidate all subsequent amendments to those Regulations with minor amendments. The amendments include removing the requirement, where building work involves inserting insulation...

www.legislation.gov.uk

That is the actual law (in England) and that is all it says.

So, what do you think?
It is not (b) or (c) so is it a new circuit?

You may decide just as well as anyone else.

 

[BobT007]

... so is it a new circuit?

You may decide just as well as anyone else.

Indeed, I do not know. I wondered if there might be some kind of official definition of a 'new' circuit, as opposed 'repaired', 'replaced', 'altered', etc., or if those of you with the experience may lean more one way than the other.

But actually, whether 'new' circuit or not, and so notifiable work or not, more importantly, do you know if there is anything in current regulations saying you are not allowed to put a 'new' connection for a hob into an old plastic cover type consumer unit where the circuit only has shared RCD protection?

 

[BS3036]

Seriously, I believe you are over-thinking it. My guess is that you did the cable change and then mentioned it to somebody who scared you into thinking you were going to jail for doing it. Assuming you did nothing stupid in routing the cable, it is probably something any of the non-electricians on this forum would have done. And my interpretation of the law would be that you did nothing illegal.

 

[EFLImpudence]

I had assumed (rightly or wrongly) that a re-connection of a cable into the consumer unit would be straightforward, with no regulations issues, as there was a hob connection there before, with 32A MCB and the shared RCD protection.

Your assumption is correct.

To expand a little, the original 6mm cable was however changed because of some damage, and a new 10mm cable run in its place. (So, is this a non-notifiable 'repair' ‘replacement’ ‘maintenance’ ‘addition’ or ‘alteration’ of an existing circuit to consumer unit, or a 'new circuit' to consumer unit ?!)

It is a repair which is not notifiable.
4mm² would likely have been adequate if the route does not involve running through thermal insulation.

So,
1.
Of most interest to me, is this query 1 - I have an older plastic cover CU, using a shared RCD for the hob circuit (and oven and socket circuits) - is it okay, within regulations / 'legally' (and safe, of course), to connect the 'new'/'replacement' cable back into the existing 32A MCB where the old hob cable connection was, like for like, no other changes. Or, would this not be allowed under the current stricter regulations ?!

That will be fine.

2. (assuming this is allowable, even if not ideal)
a)
Would this class as 'notifiable' work, according to Part P, or not? (Seems to me dependent on definition or interpretation of ‘new circuit’ I suppose vs. ‘addition/alteration/replacement/repair/maintenance’ of a circuit ??)

It is not notifiable. Part P merely states that you shall ensure it is safe.

This is Part P of the Building Regulations in its entirety:

b)
If notifiable, then obviously qualified electrician who can self-certify it is the way to go.

It is not notifiable.

If not notifiable, then could anyone, in theory (not saying I would), actually connect the cable back into the consumer unit, or does any work inside consumer unit need to be done by a qualified electrician?

Anyone may (is allowed to) do electrical work as long as you can comply with Part P.

[I actually read the Electrical Safety P document and these are the bits that have NOT helped clarify for me the notifiable/not notifiable aspect for my case:

You should read the actual law; not some guidance written by someone else about it.

Notifiable: 2.5. 12(6A) “... Where work consists of (a) the installation of a new circuit; ...”

Not Notifiable: 2.7. “... additions and alterations to existing installations outside special locations, and replacements, repairs and maintenance anywhere.”]

(As I understand it, Kitchens are no longer counted as a special location.)

Correct.

As always, thanks in advance for helpful advice and knowledge and suggestions.

 

[EFLImpudence]

Indeed, I do not know.

Yes you do.

I wondered if there might be some kind of official definition of a 'new' circuit, as opposed 'repaired', 'replaced', 'altered', etc., or if those of you with the experience may lean more one way than the other.

New means new - not there before.

But actually, whether 'new' circuit or not, and so notifiable work or not, more importantly, do you know if there is anything in current regulations saying you are not allowed to put a 'new' connection for a hob into an old plastic cover type consumer unit where the circuit only has shared RCD protection?

There is nothing saying you cannot have a 'new' (there you go; I knew you knew) connection for a hob without replacing a consumer unit.

 

[Ragnar_AT]

As far as I know, RCDs covering multiple circuits are frowned upon by many electricians but still perfectly compliant even in a new build.

 

[BobT007]

Many thanks, for your helpful, thorough, point by point replies.

I suppose I could look at an existing circuit (as opposed to a new circuit) as like Trigger’s broom (from Only Fools and Horses) – if you recall (?) Trigger was awarded a medal for saving the council money in his road sweeping job by never getting a new broom. He looked after his broom well and had had the same broom for 20 years! – maintaining it by changing the head 17 times, and the handle 14 times!

 

[Ragnar_AT]

I‘d argue if the cable takes the same route, serves the same load and is connected to the same MCB as the old one, it’s a repair/like for like replacement rather than a new circuit. Besides, you clearly aren‘t adding a circuit, the MCBs in your CU stay exactly the same. That means it’s not a significant alteration of the CU.

 

[plugwash]

As far as I know, RCDs covering multiple circuits are frowned upon by many electricians but still perfectly compliant even in a new build.

IIRC there is a regulation in BS7671 about dividing an installation into circuits to "avoid danger and minimise inconviniance". IIRC in older editions of BS7671 this regulation didn't explicitly mention RCDs, in newer editions it does.

Given that in my experiance RCD trips are about as common as overcurrent protection device trips, using a dual-RCD board makes a mockery of the idea of dividing an installation into circuits to "minimise inconviniance". I don't think the addition of a mention of RCDs to this reg.

Neverthless, the powers that be don't seem to see dual-RCD CUs as a non-compliance,

 

[ebee]

There was an article in “Wiring Matters” by the IEE (as it was then called before becoming the IET I think) that a single up front RCD was compliant with the split and divide reg ( I did not quite see it that way myself but there you go!). But it was quite a common practice back then though.

Actually I, nowadays, would choose RCBOs myself.

Back to the thread, in my opinion your intentions are compliant with Part P yes.