Kitchen Wiring Assistance

[vigalent]

Hi All....Long time lurker, 1st time poster.

Looking for some advice / guidance regarding proposed wiring for our kitchen which is to be completely renovated.

Now before the obvious, I don't intend to do the wiring myself (I will get a qualified sparks), and I know its notifiable etc etc.... What I may well do is the chasing out of the walls and installing required back boxes.

Hence what I'm trying to do, is get a feel for what I need and if I'm on the right track or not.

View media item 44007
Currently we have an old 4 way fuse box, which will be replaced with a new consumer unit as part of the process. I intend to split the existing ring main (which serves the whole house) so as to form a dedicated kitchen circuit as shown.

The second (new) ring main will serve a wall oven, combination microwave and cooker hood (if possible)..

I'm not sure of all the loadings just yet (appliances not yet fully decided) but the microwave (Zanussi) I understand is 3.4kW. Cant find loading details on the matching single Oven. The hob will be probably be an induction type.

The only items I havent included for are the under cabinet, plinth lighting and 2 illuminated shelves... Do these get wired to the lighting circuit, or can they be taken from the ring (if so how, via FCU's)?

 

[plugwash]

Now before the obvious, I don't intend to do the wiring myself (I will get a qualified sparks), and I know its notifiable etc etc.... What I may well do is the chasing out of the walls and installing required back boxes.

Make sure you agree your plans with your electrician before starting work. Different electricians often have slightly different interpretations of some of the vauger regs and you want to clear up any such issues upfront, not after you have cut big gashes in your house.

Hence what I'm trying to do, is get a feel for what I need and if I'm on the right track or not.

Sounds reasonable.

The second (new) ring main will serve a wall oven, combination microwave and cooker hood (if possible)..

I'm not sure of all the loadings just yet (appliances not yet fully decided) but the microwave (Zanussi) I understand is 3.4kW. Cant find loading details on the matching single Oven. [

3.4KW is too high for a 13A plug or FCU and too high to put on a ring. I would suggest installing a pair of dedicated 16A circuits instead.

 

[riveralt]

3.4KW is too high for a 13A plug or FCU and too high to put on a ring. I would suggest installing a pair of dedicated 16A circuits instead.

For some reason there is a tendancy for european microwave manufacturers to quote the total power for the machine by adding up the power of each of the elements together to get the '3.4kw'.
This, as you quite rightly say, equates to a 16Amp UK circuit.
But when the microwave arrives it will have a 13Amp fused plug attached.
This is because the microwave is programmed in such a way that all three elements cannot be on at the same time, or at least not all on at the same time and fully powered.
I too recently renewed the wiring in my kitchen following the building of a utility room extension. I bought this microwave combi from Ikea/Phillips.
http://www.ikea.com/gb/en/catalog/products/90123756/
I was told by the manufacturers that the oven was rated at 3.7kw so I installed a 16Amp radial for the microwave and the appropriate cooker connection unit.
When the oven arrived it was fitted with a 13Amp fuse.
Back to the OP...
If I where you I would put the main kitchen items dishwasher, washing machine, tumble dryer and fridge/freezer on there own RCBO protected circuits. I would also build capacity into your cooker circuit 10mm T&E and connection both the induction hob and oven on the same circuit.
This would reduce the need to have two ring final circuits in your kitchen and present a more balanced load across the remaining circuit.

 

[vigalent]

3.4KW is too high for a 13A plug or FCU and too high to put on a ring. I would suggest installing a pair of dedicated 16A circuits instead.

Point taken, I guess 3.4kW works out about 14amps (doh). The manual for the microwave we're looking at says...

The electric connection is made via plug (where accessible) or via an omnipolar switch,

Have I assumed wrong they meant a 13a plug?

How about the rest....does it look feasible

 

[vigalent]

If I where you I would put the main kitchen items dishwasher, washing machine, tumble dryer and fridge/freezer on there own RCBO protected circuits. I would also build capacity into your cooker circuit 10mm T&E and connection both the induction hob and oven on the same circuit.

This might not be possible. The hob and oven will be on oposite sides of the room.

 

[riveralt]

If I where you I would put the main kitchen items dishwasher, washing machine, tumble dryer and fridge/freezer on there own RCBO protected circuits. I would also build capacity into your cooker circuit 10mm T&E and connection both the induction hob and oven on the same circuit.

This might not be possible. The hob and oven will be on oposite sides of the room.

If you oven is over 2kw then it is recommended it should be on its own radial circuit.

 

[ericmark]

Think you need to go back to basics. The fuse/MCB/RCBO were there is a plug and the appliance is not fixed only protects cable. However if either the appliance is fixed or required direct connection not using a plug then it also needs to protect the appliance.

Going to the ridiculous you clearly could not run a 16mm ring and connect everything from that feeding it with a 63A RCBO as the appliance would go up in smoke before the RCBO tripped. As a result it would be normal to supply every fixed appliance from it's own RCBO/MCB so that it can be selected to match manufactures recommendations.

This would also include large free standing appliances like the washing machine and tumble drier. Although washing machine and tumble drier could be feed from a ring without overload, because the regulations say over 2kW it should have it's own supply it just not worth the hassle to feed both from same MCB/RCBO in case some one decides to be pedantic in the future.

The major problem is your not signing the installation or completion certificate and although many will look at it and use common sense the guy could decide he does not like it so will refuse to sign it off.

I have seen many times where two 2.5mm cables are taken to a grid switch which in turn feeds washing machine and tumble drier this is not a final ring it's just two conductors in parallel, often only done so one can get them in the terminals. It's being pedantic I know but you do need to get the guy who is signing for the design to do the design. As silly things like that can result in loads of hassle latter.

There are three signature installation certificates with design, installation and inspection and testing separated but you can only use them when using the LABC to issue the completion certificate.

 

[ban-all-sheds]

Looking for some advice / guidance regarding proposed wiring for our kitchen which is to be completely renovated.

Now before the obvious, I don't intend to do the wiring myself (I will get a qualified sparks), and I know its notifiable etc etc.... What I may well do is the chasing out of the walls and installing required back boxes.

Hence what I'm trying to do, is get a feel for what I need and if I'm on the right track or not.

View media item 44007

You are going into this far too deeply, and straying way into territory which belongs to the electrician.

Tell him what appliances you have.

Tell him where you want sockets.

Tell him where you want lights and switches.

Tell him what you would like on their own circuit (e.g. F/F).

And let him get on with his job.

 

[vigalent]

You are going into this far too deeply, and straying way into territory which belongs to the electrician.

Tell him what appliances you have.

Tell him where you want sockets.

Tell him where you want lights and switches.

Tell him what you would like on their own circuit (e.g. F/F).

And let him get on with his job.

Probably, but I'm an engineer by trade, planning is what we do!

Thanks all for your assistance, much appreciated.

 

[vigalent]

For some reason there is a tendancy for european microwave manufacturers to quote the total power for the machine by adding up the power of each of the elements together to get the '3.4kw'.
This, as you quite rightly say, equates to a 16Amp UK circuit.
But when the microwave arrives it will have a 13Amp fused plug attached.
This is because the microwave is programmed in such a way that all three elements cannot be on at the same time, or at least not all on at the same time and fully powered.

Ok, so now I'm slightly confused.... Just found the manual for the microwave we like and it says...

AC Voltage 220-240 V / 50 Hz
Power required 3400 W
Grill power 1500 W
Hot-Air power 1500 W
Microwave output power 1000 W
Microwave frequency 2450 MHz
Exterior dimensions (WHD) 595 455 542 mm
Interior dimensions (WHD) 420 210 390 mm
Oven capacity 35 l Weight 38 kg

But then goes on to say

The electric connection is made via plug (where accessible) or via an omnipolar switch, which is suitable for the intensity to be tolerated and which has a minimum gap of 3mm between its contacts, to ensure disconnection in case of emergency or when cleaning the microwave.

Seemingly indicating it can be fitted with a plug or via a FCU... If it is a plug, surely wont it be rated 13a and thus under the max load?

 

[riveralt]

Pretty much every domestic microwave in the uk is fitted with a 13Amp fuse plug - and certainly every free standing (appliance) microwave oven requires to have one fitted by law.
For built in ones the plug option rests with manufacturer but as I said above most domestic microwaves have them fitted.
Your only real option is to identify the oven you want and then go to a store that sells it and see if the store one has available to check it has a plug fitted.

 

[vigalent]

Pretty much every domestic microwave in the uk is fitted with a 13Amp fuse plug - and certainly every free standing (appliance) microwave oven requires to have one fitted by law.
For built in ones the plug option rests with manufacturer but as I said above most domestic microwaves have them fitted.
Your only real option is to identify the oven you want and then go to a store that sells it and see if the store one has available to check it has a plug fitted.

I'm not really bothered if it has a plug or expects a FCU, just what I need in terms of the load size as this will dictate how its wired.

The oven we are looking at (Zanussi ZYB460X) says it can be connected via 13a plug.

Either way, I guess I need to have a seperate circuit for each, so more ways required in the CU.

 

[ban-all-sheds]

AC Voltage 220-240 V / 50 Hz
Power required 3400 W
Grill power 1500 W
Hot-Air power 1500 W
Microwave output power 1000 W

As riveralt said, you can't use all 3 things at once - probably not even 2.

It'll be fine on a plug, but as it's built in and you should have an accessible means of isolation, use an FCU going to a flex outlet inside the unit.

Ask your electrician to tell you about engraved grid switches.

 

[JohnW2]

Power required 3400 W
Grill power 1500 W
Hot-Air power 1500 W

As riveralt said, you can't use all 3 things at once - probably not even 2.

I'm a bit confused here. What is 'the third thing' people are talking about? - if just the fan/light, that will always be on when anything else is on - so that's at least two at a time. However, more to the point is the fact that, as I understand it, the whole point of a 'combination oven' is that one can have microwave and conventional ('hot-air') heating working simultaneously.

Kind Regards, John.

 

[riveralt]

Power required 3400 W
Grill power 1500 W
Hot-Air power 1500 W

As riveralt said, you can't use all 3 things at once - probably not even 2.

I'm a bit confused here. What is 'the third thing' people are talking about? - if just the fan/light, that will always be on when anything else is on - so that's at least two at a time. However, more to the point is the fact that, as I understand it, the whole point of a 'combination oven' is that one can have microwave and conventional ('hot-air') heating working simultaneously.

Microwave power is the third element.
The point here is that the manufacturers adopt different ways of expressing the 'power' of their ovens. Bit like electric shower manufacturers rate their shows at both 230v and 240v but only display the 240v equivalent watt value on the box.
The critical issue is that if the manufacturers provide a plug then you use the plug.