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

[worm]

Hi all,

I'm currently in the process of extending my home to make one large living area (kitchen/living room).

I have to re-wire the entire kitchen from scratch and have done some research. I have a wall lined with units and a separate island in the middle of the room. (hob and downdraft extractor only on island)

I have X8 double sockets
X2 single oven (electric) 3.65kw / 16Amp
X1 induction hob (electric) 7.4kw/ 25Amp
X1 microwave oven (electric) 2.5 kw/ 13Amp
X1 wine cooler (electric) 0.09kw/ 13Amp
X1 warming drawer 0.40kw / 3 Amp
X1 downdraft extractor hood with motor kw?/ 13 AMP
X1 Washing machine 2.5kw/ 13Amp
X1 Dishwasher 2.5kw/ 13Amp
X1 American fridge freezer
X1 plinth fan (electric)

TOTAL 22.69 kw


I have 100m of 10mm cable

I can wire up the sockets easy, it when I get to the ovens, hob, extractor etc that it gets complex!

On a load this big worse case senarion (xmas day!) Do I need to run a radial for each oven (10mm) and one for the hob and microwave oven respectively all with their own fused wall switch on splash back?

Or can I combine the X2 ovens on one radial (10mm)
And the hob/micro/extractor on another?
Also combining their fused wall switches?

I assume I can wire the rest of the appliances off the kitchen ring? Or is this not the case...?

I work on the logic or worse case scenario (ALL appliances running at once without tripping)

Many thanks in advance

 

[bernardgreen]

I have 100m of 10mm cable

I can wire up the sockets easy

How will you get two 10mm² conductors into the terminals of a normal socket ?.

Please involve an electrician in this project.

 

[flyingsparks]

You need an electrician I'm afraid, not a forum. This is not a job for someone who obviously has no idea on how to do electrical installation. Sorry for sounding rude, but that's the fact.

 

[ban-all-sheds]

I'm currently in the process of extending my home to make one large living area (kitchen/living room).

When you applied for Building Regulations approval, what did you say, or allow to be assumed, about who would do the electrical work, and how compliance with Part P would be achieved?

If you do not actually do what you said you would do then it's quite possible (it does happen) that Building Control will refuse to give you a Completion Certificate.

I have to re-wire the entire kitchen from scratch and have done some research.

Did your research not lead you to learning about things like cable installation methods and de-rating factors, MCB characteristics, Ib ≤ In ≤ Iz, diversity, Ze, Zs, voltage drop, the pros'n'cons of ring finals vs radials including the special design considerations for the former, and so on?

I have 100m of 10mm cable

Why?

I can wire up the sockets easy

It only seems easy to you because you don't know what's involved.

Do I need to run a radial for each oven (10mm) and one for the hob and microwave oven respectively all with their own fused wall switch on splash back?

So you've done research which hasn't provided you with the necessary knowledge, and you think that you can get FCUs which will support 7.4kW appliances?

Please involve an electrician in this project.

("Involve" ≡ "employ to do it all".)

 

[worm]

Thank you for your replies!

I will indeed involve an electrician, to comply with Building regs and obviously when it come to selling house to have ALL necessary paperwork!

6mm cable may surfice indeed for oven/hob radials (which I also have) but I have 10mm incase dependent on wiring.

Well of course their will be an FCU to support a 7.4Kw hob or why else would they manufacture it! Try a Rangemaster at about 13.4kw!!

Its kinda basic (sorry to sound rude)... but if the load exceeds the wire capacity it will trip...

My old man has a physics degree and said its simple (NASA scientist lol) , just hadn't asked him! I will however, employ an sparky to sign off and approve all work at every aspect and stage despite his help!

I guess having built the house ground up from a £5 DIY book myself I just wanted some helpful advice on here, but there comes a time when certain professions need to step in!

I will get the answer and post it on here to help ANYONE else in my situ... with clear illustrations too! I know sparky's may be reluctant to post answers for obvious reason, so I understand and appreciate that & the advice, but its nothing that anyone cannot obtain thru reading a book or youtube. Just needs paperwork to comply with regs, which is a given at every stage of the process.

I'm a firm believer that anything's possible... and this is!

Anyone thinking of re-wiring a house themselves without part P sign off.... well, don't do it!

Sorry if I came across as naïve, well I wanted too to encourage help but its more intrigue as knowledge is power! I'm not one to just pay someone to do something and walk away otherwise you never understand it... then next time the problems arises (next project) you already have the solution! only a lazy person with no ambition would do that in my humble opinion.

Thank you all once again fro your time

Will post detailed solution ASAP but its complex as it involves all the above, x3 outside lighting, outside garage RCD and wifi underfloor heating and a X4 multi zone RGBW LED switch in additional to another 3/ 4 lighting zones ALL with a concrete sub floor! Nightmare believe me for ducting downdraft extractors and plumbing!

Blackpool illuminations

 

[ban-all-sheds]

I will indeed involve an electrician, to comply with Building regs and obviously when it come to selling house to have ALL necessary paperwork!

Which means you must apply for Building Regulations approval before you start, and they must agree with what your idea of "involving" an electrician means, and you must find an electrician who also agrees, also before you start.

Well of course their will be an FCU to support a 7.4Kw hob

There won't.

or why else would they manufacture it!

They don't.

They cannot.

It is not possible to make one.

Try a Rangemaster at about 13.4kw!!

Why?

Its kinda basic

I will however, employ an sparky to sign off and approve all work at every aspect and stage despite his help!

Does he know about this?

I guess having built the house ground up

So you must have applied for Building Regulations approval. So, again, when you did that, what did you say, or allow to be assumed, about who would do the electrical work?

Will post detailed solution ASAP but its complex as it involves all the above, x3 outside lighting, outside garage RCD and wifi underfloor heating and a X4 multi zone RGBW LED switch in additional to another 3/ 4 lighting zones ALL with a concrete sub floor!

You cannot do work of that scope with your current method. Wiring a house, installing new CUs, outside supplies, submains etc is not a trivial job, and I can assure you that it involves knowing far more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. You've already shown that you have some dodgy misconceptions - what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

I agree that it's quite possible for you to learn, but I think you have underestimated how much you have to learn. If you are going to press on and DIY the electrics, you'll have to put that on hold, not for days, not for weeks, but for months.

 

[JohnW2]

6mm cable may surfice indeed for oven/hob radials (which I also have) but I have 10mm incase dependent on wiring. ... Well of course their will be an FCU to support a 7.4Kw hob or why else would they manufacture it! Try a Rangemaster at about 13.4kw!! ... Its kinda basic (sorry to sound rude)... but if the load exceeds the wire capacity it will trip...

One of the many things you need to learn about is the concept of diversity. After application of diversity, a domestic cooking appliance rated at 7.4kW (at 240V) is considered to be a load of about 15.6A (at 230V), whilst a "13.4 kW (at 240V) Rangemaster" would be considered as a load of about 22.8A (at 230V) after application diversity. Although one wouldn't usually go to such extremes, give ideal installation methods, the former could theoretically be supplied by 1.5mm ² on a 16A MCB and the latter by 2.5mm² cable on a 25A MCB. In practice one would probably choose 4mm² cable.

Although 6mm² cable is often seen in domestic cooker circuits, it is nearly always totally unnecessary - 4mm² cable on a 32A MCB will (after diversity) usually support about 19kW of "rated cooking appliance loads".

Maybe it is "kinda basic" (certainly for an electrician or competent DIYer), but that only becomes the case after you know and understand the concepts and issues involved.

Kind Regards, John

 

[EFLImpudence]

Although 6mm² cable is often seen in domestic cooker circuits, it is nearly always totally unnecessary - 4mm² cable on a 32A MCB will (after diversity) usually support about 19kW of "rated cooking appliance loads".

Just to say that it is unnecessary now with MCBs.

It had to be used with rewirable fuses because of their characteristics

Because it was always used, people still use it because that's what was always used so that's what they use.

Having said that, in case they read this, from reading other forums the 'fashion' seems to be to use 10mm² just in case.
Just in case you need to supply a flat from your cooker circuit, I suppose.

 

[JohnW2]

Although 6mm² cable is often seen in domestic cooker circuits, it is nearly always totally unnecessary - 4mm² cable on a 32A MCB will (after diversity) usually support about 19kW of "rated cooking appliance loads".

Just to say that it is unnecessary now with MCBs. ... It had to be used with rewirable fuses because of their characteristics

True, IF one wanted to use a 30A rewirable fuse (which semed to be 'the norm'). However, given that, after application of diversity, a 20A fuse would presumably have been OK for up to about 10.8kW (at 240V), in which case 4mm² cable would presumably have been adequate, even then, wouldn't it?

Kind Regards, John

 

[ericmark]

It is near impossible for any DIY guy to do his own electrics for a reasonable price. The test gear required costs too much even if you know how to use it.

However people do clearly DIY electrics and get away without testing the Emma Shaw cases are thankfully small.

Getting power to an island is always a problem be it from above or below and as a result clearly you need to work out the pros and cons. Much depends on what the floor is made from.

Keeping water, heat and electrics apart is also a challenge with commercial we use power track or similar and the island simply plugs in.

but these can be expensive. You could have a simple socket

dangling down from the ceiling into which the island plugs into. Or it could be hard wired.

It is likely somewhere you will want to be able to isolate and clearly some careful planning is required and also some thought as to time scale before next refurbish. Commercial office and kitchens are continually changing and so they want plug in systems. I have changed cooker, dishwasher, and fridge/freezer but kitchen layout has not changed in 20 years since extension was built.

B&Q is not really going to give you ideas on how to supply an island. Their display is changed regular so likely sockets in the floor. So question one is will there be a distribution board in the island or will it have multi-feeds.

The same questions arise for most other kitchen outlets. Using a grid switch arrangement and a row of isolators with radials or using a ring final system needs careful consideration.

As we look at equipment we need to consider how it will be used. For example will the washing machine and tumble drier be in the kitchen? They are nothing to do with cooking. Other than tumble drier every item will auto switch on and off so it's not as simple as adding all power requirements together.

Christmas day is not the worst as Turkey is cooked normally over night to me the most prolonged load is the pressure cooker for normal cooking and mashing beer for specialised cooking. The large pan used for beer can take half an hour on full heat at 3.7kW on the induction hob nothing else will ever need heating for so long and with so much power.

Downdraft extractor hood with motor kw?/ 13 AMP I would assume means a large cut out in the floor to the outside. I would consider making it a bit larger and having the supply cables in the same channel with of course some fire stopping divider between them. Since the extract channel will need cleaning from time to time I would assume there would be access panels which would also mean power could also be accessed. Having a mini-consumer unit in the kitchen means no need for any grid switches.

When you have planned out your kitchen then is the time to ask questions. And really one at a time. Be it how to get power onto an island or how often does a down draft extractor air way need cleaning. I personally don't know the answer but I would hope you do by now.

 

[EFLImpudence]

True, IF one wanted to use a 30A rewirable fuse (which semed to be 'the norm'). However, given that, after application of diversity, a 20A fuse would presumably have been OK for up to about 10.8kW (at 240V), in which case 4mm² cable would presumably have been adequate, even then, wouldn't it?

Yes, but installing standard circuits with no knowledge of the intended future use a 30A 3036 would require 6mm² cable.

I've never seen an old 20A or 25A 3036 with 4mm² cooker circuit.

 

[JohnW2]

Yes, but installing standard circuits with no knowledge of the intended future use a 30A 3036 would require 6mm² cable. ... I've never seen an old 20A or 25A 3036 with 4mm² cooker circuit.

[I can't say I've seen that, either - but my experience is very limited] Interesting - so 'they' were perhaps not acting particularly logically (or not applying diversity as we know it) back then, either?

Kind Regards, John'

 

[Chri5]

Hi all,

I'm currently in the process of extending my home to make one large living area (kitchen/living room).

I have to re-wire the entire kitchen from scratch and have done some research. I have a wall lined with units and a separate island in the middle of the room. (hob and downdraft extractor only on island)

I have X8 double sockets
X2 single oven (electric) 3.65kw / 16Amp
X1 induction hob (electric) 7.4kw/ 25Amp
X1 microwave oven (electric) 2.5 kw/ 13Amp
X1 wine cooler (electric) 0.09kw/ 13Amp
X1 warming drawer 0.40kw / 3 Amp
X1 downdraft extractor hood with motor kw?/ 13 AMP
X1 Washing machine 2.5kw/ 13Amp
X1 Dishwasher 2.5kw/ 13Amp
X1 American fridge freezer
X1 plinth fan (electric)


Read more: //www.diynot.com/diy/threads/h...appliances-help.426123/#ixzz3RGJ8CycW[/QUOTE]

Island served with two circuits, one for hob radial 4mm or greater. Run another 4mm and have a 32 amp radial for sockets.

Rest of room two radials 4 mm or (if you want to be old fashioned) 2 x rings.

Although you have concentrated on the fixed appliances don't forget the toaster, the coffee maker, the kettle, the tap boiled water.

You need to consider the use on each circuit including the stuff I've mentioned. The key being if everything is on, on a circuit you really shouldn't be going over the circuit rating.

If you are likely to have everything on and the plinth heater, there might be a requirement for an additional circuit.

The island extractor will be a feed over the ceiling, likely a spur from one of the general circuits. It's acceptable to have a switched fuse spur remote from the hood. The hood will have its own on/ off and speed buttons.

The ovens will be fine on the cable you have, one feed to a 40 amp+ switch and split feeds on to the ovens.

Have you considered banking switches in to groups to avoid peppering walls with back boxes. MK or similar grid systems?

Have you considered what will happen with smoke detectors, a freezer on a general main when the rcd trips while your on holiday and counter lighting?

Is your existing board big enough? Is it a split rcd or rcbo per circuit?

Not all electricians bite, the earlier you bring someone in the more likely you can agree a method that allows you first fix, a proper design and importantly a cert at the end of works.

 

[EFLImpudence]

[I can't say I've seen that, either - but my experience is very limited] Interesting - so 'they' were perhaps not acting particularly logically (or not applying diversity as we know it) back then, either?

Mmmm. They probably were.
Don't forget they always had a socket with the switch.
So, 25A after diversity.

A 25A (20A for cooker) would allow a 10.4kW cooker (doubtful?) and
a 20A (15A for cooker) would have been too low.

Also, a 30A fuse was used for the ring so they din't need any 20 or 25A fuses.

 

[JohnW2]

Also, a 30A fuse was used for the ring so they din't need any 20 or 25A fuses.

That much is certainly true.

Do I take it that, for the same reason, 4mm² sockets radials protected by a 30A 3036 were also not possible?

Kind Regards, John