HUGE KITCHEN RE-WIRE & ISLAND (10 appliances) help!!!

[EFLImpudence]

mistake

 

[JohnW2]

mistake

[I'm glad I'm not the only person that happens to ]
I look forward to hopefully seeing a non-mistake version in due course!

Kind Regards, John

 

[EFLImpudence]

I wrote a long answer but then I stumbled upon what I think you are getting at but I can't explain it, either.

Please answer this:

A ring circuit with 2.5mm² cable to method C -
What IS the Iz of the cable with a 32A MCB?
What IS the Iz of the cable with a 30A 3036?

 

[JohnW2]

I wrote a long answer but then I stumbled upon what I think you are getting at but I can't explain it, either. Please answer this:
A ring circuit with 2.5mm² cable to method C -
What IS the Iz of the cable with a 32A MCB?
What IS the Iz of the cable with a 30A 3036?

Well, in terms of my understanding (which seems to me to be a common sense one) of what CCC/Iz means, the answer in both cases is 27A (assuming no other de-rating factors) - and it would still be 27A for any type of OPD with any In. As far as I am concerned "CCC" (or Iz) means exactly what it says - and, for a given cable installed in a given way, will be the same whether it is protected by a 6A OPD or a 100A OPD, and whether it's protected by an MCB or a 3036 fuse. Of course, some of those OPDs would not allow 27A to flow for very long (or may allow a lot more than 27A to flow for a long time), but that would not alter the "current-carrying capacity" of the cable, as installed.

What differs according the the OPD type is the maximum OPD In which will afford adequate protection to a cable with the CCC/Iz in question - as we know, if CCC is 27A then (in a radial circuit) that would mean a hypothetical MCB with In of 27A or a hypothetical 3036 fuse with an In of about 19.6A. However, in both cases, as far as I am concerned, the "CCC"/Iz of the cable is 27A.

Kind Regards, John

 

[EFLImpudence]

I wrote a long answer but then I stumbled upon what I think you are getting at but I can't explain it, either. Please answer this:
A ring circuit with 2.5mm² cable to method C -
What IS the Iz of the cable with a 32A MCB?
What IS the Iz of the cable with a 30A 3036?

Well, in terms of my understanding (which seems to me to be a common sense one) of what CCC/Iz means, the answer in both cases is 27A

Yes, along with the rest of your post, that's what I realised (I think) you were getting at.

However, if the cable were installed in conduit for part of its run then the Iz of the cable would reduce to 20A (correct?).
The MCB circuit would still be compliant but the 3036 circuit would not.

If not wishing to reduce the 3036 In to 14.5A (10A or 15A?), do you agree that the cable would have to be increased to one with a method A CCC of (20/0.725) 27.6A?
I.e. 6mm² where its Iz would still be 32A.

Whilst I have been disagreeing with you, is the outcome not the same?


Do we need another term instead of Iz for this situation, i.e. rings?

 

[JohnW2]

Please answer this: A ring circuit with 2.5mm² cable to method C -
What IS the Iz of the cable with a 32A MCB? What IS the Iz of the cable with a 30A 3036?

Well, in terms of my understanding (which seems to me to be a common sense one) of what CCC/Iz means, the answer in both cases is 27A

Yes, along with the rest of your post, that's what I realised (I think) you were getting at.

I'm glad that you now at last understand what I've been saying.

However, if the cable were installed in conduit for part of its run then the Iz of the cable would reduce to 20A (correct?).

Indeed

The MCB circuit would still be compliant ....

I presume you must be talking about a ring final, since a cable in a radial with a CCC of 20A protected by a 32A MCB obviously would not be acceptable.

... but the 3036 circuit would not.

THAT is the very issue/question I've been addressing all along. In common senses terms, I agree that a Method A 2.5mm² ring protected by a 30A 3036 ought not to be acceptable. However, if you now accept 'my' definition of CCC/Iz, and if you accept that such is the meaning of "current-carrying capacity" in both 433.1.202 and 433.1.204, then the wording of 433.1.204 appears to be saying that a Method A 2.5mm² ring protected by a 30A 3036 is just as acceptable as the same circuit protected by a B32. That has been the point I've been trying to make all along. I agree that it does not make electrical sense, but it appears to be what the regulation is saying.

If not wishing to reduce the 3036 In to 14.5A (10A or 15A?), do you agree that the cable would have to be increased to one with a method A CCC of (20/0.725) 27.6A? I.e. 6mm² where its Iz would still be 32A.

As above, you're trying I talk electrical common sense. What I've been discussing, all along is what 433.1.204 actually says.

Do we need another term instead of Iz for this situation, i.e. rings?

I don't think so. Provided we stick with using CCC/Iz to 'mean what it says' (i.e. don't adjust it for OPD type) everything is fairly clear, and it's then up to 433.1.204 to decide what degree of 'under-protection' (as compared with what would be required in a radial) is acceptable in a ring. The one thing seemingly 'wrong' with 433.1.103, as worded, (at least, per my interpretation) is that it appears to say that one can have "20A CCC" ring ('my' meaning of CCC) protected a 30A 3036 or a 32A MCB. If that was changed to "20A 3036 or 32A MCB, it would probably be about right - and would be roughly 'equivalent' to the corresponding situation with radials.

Kind Regards, John

 

[EFLImpudence]

I'm still not comfortable with your reasoning because of what the regulations might actually say, nor usually are you.

Do you not consider "under the particular installation conditions concerned" (in Iz definition) to include the OPD?

 

[JohnW2]

I'm still not comfortable with your reasoning because of what the regulations might actually say, nor usually are you.

I'm with you electrically. However, I'm suggesting that what the words of the reg actually says is not what it should say (in terms of electrical common sense)

Do you not consider "under the particular installation conditions concerned" (in Iz definition) to include the OPD?

The short answer is 'no' - I believe that CCC/Iz relates to how much current a cable can safely carry (under the particular installation conditions), regardless of what (if anything) is protecting it. The cable surely still has the same 'CCC' even if its not protected at all!

Whatever, as I keep saying in support of my view, if 'your' interpretation were correct, such that you had to multiply the tabulated It by 0.725 to get 'CCC' when the OPD was a 3036, 433.1.202 would then cause you to multiple that (already multiplied by 0.725) figure by a second 0.725 - which is obviously wrong.

Kind Regards, John

 

[EFLImpudence]

]I'm with you electrically. However, I'm suggesting that what the words of the reg actually says is not what it should say (in terms of electrical common sense)

Yes, but usually you would be arguing against the wording, not for the thing it seems to allow.

The short answer is 'no' - I believe that CCC/Iz relates to how much current a cable can safely carry (under the particular installation conditions), regardless of what (if anything) is protecting it. The cable surely still has the same 'CCC' even if its not protected at all!

It does, but must have a lower Iz, or whatever it may be called, so that the possible overload can be safely handled.

Whatever, as I keep saying in support of my view, if 'your' interpretation were correct, such that you had to multiply the tabulated It by 0.725 to get 'CCC' when the OPD was a 3036, 433.1.202 would then cause you to multiple that (already multiplied by 0.725) figure by a second 0.725 - which is obviously wrong.

I still do not understand why you think it would be done twice.
.202 is a general statement of fact and .204 would have already taken such into account as it quotes various OPDs.


I think all the confusion is the result of the anomalies of ring circuits.

The only true comparison would be a 2.5mm² ring installed to method A (if anyone were daft enough to do it).
This would consist of the (minimum allowed size) cable actually having the (minimum allowed) CCC and Iz of 20A.

With a 32A MCB this would have allowed for a current of 46.4A (32A x1.45) for an hour without damage.
It clearly would not be satisfactory with a 30A 3036 where the current may be 60A (30A x2) for an hour.

 

[JohnW2]

]I'm with you electrically. However, I'm suggesting that what the words of the reg actually says is not what it should say (in terms of electrical common sense)

Yes, but usually you would be arguing against the wording, not for the thing it seems to allow.

You're still misunderstanding me. I agree with you about what should (and should not) be allowed - I am suggesting that the wording of 433.1.204 appears to allow something that neither you nor I believe should be allowed. I am not 'arguing for' the thing which the words of the reg appears to be allowing (I would say wrongly).

The short answer is 'no' - I believe that CCC/Iz relates to how much current a cable can safely carry (under the particular installation conditions), regardless of what (if anything) is protecting it. The cable surely still has the same 'CCC' even if its not protected at all!

It does, but must have a lower Iz, or whatever it may be called, so that the possible overload can be safely handled.

No. As I keep saying, it's nothing to do with characteristics of the cable (CCC/Iz). It's simply a matter that, with some OPDs, the maximum In of the OPD to give adeqaue protection to a cable of a particular CCC is lower than would be the maximum In requird for some other type of OPD. Nothing to do with the cable or its CCC/Iz changing with different OPDs.

Whatever, as I keep saying in support of my view, if 'your' interpretation were correct, such that you had to multiply the tabulated It by 0.725 to get 'CCC' when the OPD was a 3036, 433.1.202 would then cause you to multiple that (already multiplied by 0.725) figure by a second 0.725 - which is obviously wrong.

I still do not understand why you think it would be done twice.

With the view you expressed (and with which I disagree) "current-carrying capacity" would be obtained by multiplying the tabulated It by 0.725 if protection is by 3036 - hence for 2.5mm² Method C about 19.6A (27A x 0.725). 433.1.102 then says that if protection is by a 3036, it's In must not be greater than 0.725 times the "current-carrying capacity" (which, in previous sentence, you would have calculated as ~19.6A). You would therefore conclude that the In of the 3036 could not be greater than about 14.2A (19.6A x 0.725) - which is clearly wrong, and results from your having multiplied by 0,725 in the previous sentence and (per 433.1.202) by 0.725 in this sentence. That's twice

I think all the confusion is the result of the anomalies of ring circuits.

The entire discussion is about ring circuits, since all I'm talking about is the wording of 433.1.204!

The only true comparison would be a 2.5mm² ring installed to method A (if anyone were daft enough to do it). This would consist of the (minimum allowed size) cable actually having the (minimum allowed) CCC and Iz of 20A. With a 32A MCB this would have allowed for a current of 46.4A (32A x1.45) for an hour without damage.

Yes, 46.4A for an hour through the MCB, but the whole concept of the ring is that a lot less than that ('ideally' only a half) would go through the cable in either leg of the ring. Someone has decided that, in a ring, it is acceptable for the OPD's In to be 1.6 times greater than the maximum which would be allowed for a radial (i.e. a 32A MCB protecting a cable with CCC=20A).

It clearly would not be satisfactory with a 30A 3036 where the current may be 60A (30A x2) for an hour.

Quite, that would be a 'dispensation ratio' (ring/radial) of 3.0 (60/20), as compared with the 1.6 'allowed' with an MCB - and clearly far too great. That's why I believe that 433.1.204, as worded, is wrong.

Kind Regards, John

 

[worm]

Hi All, wow very interesting read!

Thank you all indeed.

The Centre Island will have X2 sockets only with downdraft extractor hood in island and induction hob! These sockets will be hidden under the breakfast bar end to keep look minimal and they are only there as a precaution or for things such a laptops/iphones/ipads and so on! The only issue perhaps with this Is that you have unsightly cable running! But it also has the ability to have a kettle/toaster on the island should one choose to!

I will run a dedicated 6mm radial circuit to the 7.4kw hob and the sockets will be powered off the kitchen socket ring (2.5mm also on its own circuit)

The cable for this will be ducting in thick conduit in the concrete sub floor that I have chased out with the 6mm hob wire too!

The extractor 100mm flat channel ducting also run parallel to this in the floor where I have once again rebated the concrete (making sure no tile joints reside over the top of this) I will however cover with 2/3mm steel metal for protection and stability for the flooring!

Once this goes down it is staying down for my lifetime! Due to the nature of this build and the bespoke design the layout will never change!

The floor will be made level with levelling compound then insulated board for the under floor heating and primer, with stone/porcelain tiles on top! If there is ever an error with the U floor heating you can locate the problem to within a tile (600mmx600mm) and repair!

Worse case is the central heating for my X2 column Rads bursts, but then thats life!

The appliances will then be run on another dedicated 2.5mm circuit rom the CU which incidentally I will have to change to a 15 way box as I have too many circuits for the current 10 way CU!

The ovens will also have their own circuit 2.5mm inline with Sparkys guidance!

To alleviate the isuue of a splash back being peppered in switch plates X6/7 I have come up with an idea to house ALL the fused switched within some commercial trunking hidden within a 300mm unit that covers the Steel where the extension was built! This solves the problem of unsightly sockets, makes use of the space, hides the steel and therefore provides me with 1 dedicated switch board that is also easily accessable!

The under floor heating wifi touch pad with reside on the splash back with x2 sockets for toaster/kettle! Only x3 sockets

I have already considered ALL other wiring having ran X3 twin shotgun cable for SKY+ to x3 zones as more than 1 TV in room, X1 coax to each zone, CAT5 cable and telephone cable all wired into a router under the stairs for my network and so then my SMART TVs can have internet even if wifi stops working!


The RGBW led X4 zone multi-switch will reside as you walk in the room by the other X4 way light switch the the X4 other lighting zones with JCC FG LED dimmable downlights! The dimmable wall plate for this is about £90 for this but worth it! Polished chrome with blue led light around touch pad! The drivers for these will also reside in a ceiling space that is accessible, should a problem arise in the future!

I have also left a socket in the ceiling (hidden in recessed ceiling area near my lounge RGBW LED lighting zone) for the use of a OHP on my large wall for footy and boxing or just movie nights or XBOX live... the light will then gush out rather that be intense to create a great effect!

I've been mind full to measure and record every pipe wire and joist for future reference and future home owners on CAD!

Measure twice cut once always!

I have 6 metre 5 pane anthracite aluminium bi fold across the entire rear of the property (FLUCH TRACK) so no lip, the outside will be decked to create one seemless inside/out space!

I do eventually hope to sink a hot tub into the garden and decking so you step down into this, I have to look into H&S for this and have already considered powering this and the outside garage on own RCD, with SKY+ cable for future proofing summer TV!

From the outset this job has been complex, bespoke in every aspect and a 100% learning process for myself and 24/7 living hell as living in property from day 1! Xmas day I gave myself 5 hours off that has been it... I have thought about the wiring and layout every day from digging the initial foundations back in July 14. I hope to complete the project in may 15...

So thank you for all your responses and help! I have employed a sparky and come to an agreement that I will chase all the walls sockets and run wire in as long as he connects ALL sockets and CU and tests!

This is to reduce cost, but also give me the relevant certification I need!

I'm aware this is far beyond ANY normal house refurb, but it depends what you want in life! I'm a firm believer that in life there are no limits, only those you impose upon yourself! I have completed the build on a shoe string budget, but it not to sell hence work undertaken. Just to create a place to call Home! I've loved every aspect of it, and take genuine interest in everything, thinking how to make the next time even better. My dream is to property develop, its my 3rd project and don't think you can ever stop learning.



I hope that this can inspire anyone else who reads this forum or simply help as it did me!


Thank you all again, will post pics ASAP

If anyone has any suggestions or more help then please do[/youtube]

 

[jamesmcbride]

Really looking forward to the pics, it sounds amazing!

 

[ban-all-sheds]

I have employed a sparky and come to an agreement that I will chase all the walls sockets and run wire in as long as he connects ALL sockets and CU and tests!

This is to reduce cost, but also give me the relevant certification I need!

I'll point out, for the last time (and I'll use big letters as you don't seem to have seen it before)

IF THAT IS NOT WHAT YOU AGREED WITH YOUR LABC AT THE TIME YOU APPLIED FOR BUILDING REGULATIONS APPROVAL YOU WILL END UP WITH AN EXTENSION ON YOUR HOUSE WHICH HAS NO BUILDING REGULATIONS COMPLETION CERTIFICATE.

 

[worm]

DID I EVER MENTION IT WASNT AGREED?

For a complete novice maybe... as they know no better.

To clarify, I have build my extension with my Architect, extensive careful planning and did so through permitted development (planning portal is an amazing site) and "agreed" continual communication, with architect, Engineers (steel work as I had a 7m 305 1000kg steel go in using X3 genie lifts!!!! biggest steel to ever leave his yard apparently but has been calculated by structural engineer to take into account a loft conversion in the future and building officer and builder (me) and heating engineer (GAS) whilst ensuring all insulation is to spec to achieve the required ratings needs and the UV value in the room as 64m2 and a lot of glass resides here. Everything including the log burner has been done with the relevant skill and qualification needed eg HETAS... FENSA, LABC, structural engineers cals for all X5 steels and the pad stones these reside on (1.5m2 pads 1.5m deep) I had to undermine the existing foundations and re-enforce with 20mm steel rods... by far the biggest job to date! Without or wrong the house would no stand!

I applied for building regulations way before any work commenced and have liaised with the firm in question and there chief building inspector at every stage of the build, complying with all materials used (reclaimed to match existing house/surrounds) ONLY continuing with ANY works once each stage is not only photographed, been inspected, approved and a record kept taking ANY ADVICE or "helpful" CONSTRUCTIVE CRITISISM into account to ensure complete compliance with building regs!

Communication is key, always.

Being project manger/planner/builder/QS/sourcing all materials/tea maker and anything else whilst holding down my 9-5, with x2 dogs and having my partner walk out and loosing my job of 10 years has indeed set me back and been the biggest challenge and test of my character in my life...

I have my health & really that's all that matters. The house is material

I hope this answers your point though, but more so helps anyone else reading this! Without any of the above house re-sale would be near on impossible and all insurance policies void. Its peace of mind too, nothings cheap but doing things right will deff pay dividends in the return...

None more so than the sense of achievement.

 

[ban-all-sheds]

DID I EVER MENTION IT WASNT AGREED?

No, but nor did you ever say it was, despite being asked. And you did begin here asking questions which showed that you were not competent to be doing the electrical work yourself and that you didn't have anyone involved who was.

And trust me - we have had people here who have done all the application, communication etc thing with Building Control, failed to notice that they'd said nothing to counter assumptions on their LABC website about electrical work, or failed to notice what their architect or technician had said on the application (or if they had noticed either, failed to grasp the importance), assumed that they could "get an electrician to connect it and sign it off", and then found that what they had was a building project done and a refusal by their LABC to issue a completion certificate.