Kitchen main ring

[mk2000]

Hi, I wonder if anybody can help me please. I need to rewire my kitchen and planning for a new 32a kitchen main ring on 2.5mm cable for below applainces.

1. Washing Machine
2. Dishwasher (13A)
3. Cooker hood
4. Single Oven (16A)
5. Gas Hob ignition

All the kitchen appliances have there own fused plugs which will be connected to switched or unswitched outlets,

All grid switches are 20A

Any advice on the below diagram if it make any sense,


View media item 81221
Your help will be highly appricaited

Thanks,MK

 

[Taylortwocities]

I am sorry top be hard on you, but some very basic points

1. are you aware of the legal requirements regarding the installation of new circuits? You are going to have to raise a building notice with your local authority first, and be prepared to demonstratete that everything you have done complies with BS7671 and Building Regulations. My guess is that you wont be able to. Get a registered electrician.

2. You cannot connect a 16amp load to a ring final. It needs its own dedicated circuit.

3. Does your consumer unit have RCDs on the circuit(s) that will be added?

 

[mk2000]

Thanks for your reply TTC

1. This circuit is suggested by an registerd electrician, please dont take it wrong, so assuming this circuit is designed as per legal requirements, (possibilly my electrician is not fully aware of it)

I am not sure about raising a building notice with my local authority, how does it work, do i need to get some sort of approval before carrying out this work. ?

2. This is where i am quite confused, so raised this issue in the form to have more opinions on this, my electrician told me that this is OK to connect 16A single oven to 20A DP Grid switch as per circuit in the picture

3. Yes, this circuit will be added on RCD

Thanks, MK

 

[ericmark]

The rules are confusing I will admit.

1) The load current in any part of the circuit should be unlikely to exceed for long periods the current-carrying capacity of the cable (Regulation 433.1.5 refers). This can generally be achieved by:
(i) locating socket-outlets to provide reasonable sharing of the load around the ring
(ii) not supplying immersion heaters, comprehensive electric space heating or loads of a similar profile frog the ring circuit
(iii) connecting cookers, ovens and hobs with a rated power exceeding 2 kW on their own dedicated radial circuit
(iv) taking account of the total floor area being served. (Historically, limit of 100 m² has been adopted.)
2) 560.6.8 Special requirements for safety services having sources capable of operation in parallel.

So first are you fitting a ring final or conductors in parallel? The grid switch will not take 6mm² cable and the link to next switch so using two 2.5mm² feeds allows one to physically get the cable into the switches. If there is nothing else from the pair of cables then it's not a ring final and you could feed a 15A oven.

Dedicated may be seen as stretching to include cooker hob with cooker but not dish washer.

It is common to have a ring final for kitchen alone but you have to satisfy the LABC inspector and it is all dependent on how much he wants to follow BS7671 so only person who can say yes or no is the LABC inspector.

Electricians have to satisfy their scheme provider and DIY has to satisfy LABC inspector. In the main the same but there are some differences. For example one could fit a German Schuko socket to supply your 16A oven and the LABC could pass it but an electricians scheme provider would not permit it as against BS7671 but not against the law.

I know it seems daft but BS7671 is not law Part P is but the electricians contract with the scheme provider means for him in real terms the BS7671 is law.

 

[JohnW2]

2. You cannot connect a 16amp load to a ring final. It needs its own dedicated circuit.

Whilst that is obviously true, per se, there appears to be a bit of confusion/uncertainty about the situation, given that (as also confirmed by the diagram in the OP):

... 4. Single Oven (16A) ... All the kitchen appliances have there own fused plugs which will be connected to switched or unswitched outlets

Kind Regards, John

 

[JohnW2]

I am not sure about raising a building notice with my local authority, how does it work, do i need to get some sort of approval before carrying out this work. ?

Quite apart from the electrical issues (including the design and required testing etc.) ... probably the most important thing for you to know is that if you do the work yourself (indeed, if it is done by anyone other than a registered 'self-certifying' electrician), and IF it really is a 'new' ring circuit (rather than a modification of an existing one) you have to submit your 'notification' to your LA before any work starts, and that notification has to be accompanied by a fee which, depending on which LA you have, could be anything up to 'a few hundred pounds'. If a self-certifying electrician does the notification, the fee is trivial.

Kind Regards, John

 

[mk2000]

Thanks for your reply Mark,

The original plan was to fit a ring final to feed all kitchen appliances including oven, but after checking rule (iii) in your reply, i checked my oven(Bosch HBA63B251B) specification, it says require 3.6kw electrical connection with 16A fuse,

Does that mean oven need to be on its own dedicated radial circuit on 2.5mm cable, which i believe can be manage in my case as doing complete rewiring in the kitchen. and rest of the appliances on 2.5mm ring final, please confirm if this will work. ?

Please check and confirm if this new diagram make any sense

View media item 81223
Thanks,MK

 

[JohnW2]

The original plan was to fit a ring final to feed all kitchen appliances including oven, but after checking rule (iii) in your reply, i checked my oven(Bosch HBA63B251B) specification, it says require 3.6kw electrical connection with 16A fuse,

Fair enough - I take it that this means that it doesn't come with a (13A) fused plug,a s you had suggested?

Does that mean oven need to be on their own dedicated radial circuit on 2.5mm cable, which i believe can be manage in my case as doing complete rewiring in the kitchen. and rest of the appliances on 2.5mm ring final, please confirm if this will work. ?

Yes, you could do that, provided the dedicated circuit for the oven had a 16A or 20A MCB in the CU. However, whilst you were doing it you might want to consider using 4mm², or even 6mm² cable for this 'cooker' circuit (those sizes being 'normal' for a cooker circuit), in case you (or someone) wanted to use it to power a whole cooker (over+hob) in the future, rather than just an oven.

Kind Regards, John

 

[JohnW2]

Please check and confirm if this new diagram make any sense
View media item 81223

I'm sure that bit wasn't there when I just replied!

No, you can't do that. You can have neither a (13A max) FCU nor a (13A) socket/plug supplying an appliance which requires 16A. For the 'dedicated oven circuit', you need a 16A MCB in the CU and then a hard-wired direct connection (probably using a 'cooker connection' outlet) to the oven.

You seem to have an oven which was designed for the European market, where 16A circuits and 16A plugs are the norm.

Kind Regards, John

 

[ban-all-sheds]

MK - I really don't think you know enough about circuit design to be doing it. Please get an electrician.

 

[JohnW2]

MK - I really don't think you know enough about circuit design to be doing it. Please get an electrician.

... and probably not the 'registered electrician' who suggested the design that the OP initially proposed.

Kind Regards, John

 

[ericmark]

using a plug like this

you could plug in a oven as to a socket like this

the IET/BSi does not permit there use so an electrician who is a scheme member can't use them. But he can fit these

rated at 15A but the big thing with a 16A and 15A socket the plug does not have a fuse so can't be used off a supply any larger that 16 or 15 amp.

There is an advantage with plug and socket in that it is easy to remove for maintenance but really it is not required a cooker connection unit does the same thing.

You can get 15A plugs with a fuse but the fuse is only 5A not 15 amp so rather pointless.

There was one guy on this forum who wanted to DIY and paid the LABC but it cost a lot more then he thought as on top of the £200 fee he was also charged same again for inspecting and testing.

The job I did I was lucky both before the double charge came in and for disabled so no charge. However the checks before they allowed me to DIY were extensive my son are the time with just a C&G 2391 and 2381 (as it was then) was not allowed to test and inspect I was permitted as I had a degree. Had I not been permitted then it would have cost around £200 for testing.

So theroy may say you can DIY but in practice you can't. Clearly you can try to find loop holes in the law but in real terms it does not matter if nothing goes wrong unlikely the LABC will start a court case and if it does any attempt to show how you did not need to notify will come to nothing you will still be found guilty. So be under no illusion if you DIY the buck stops with you including likely problems with any insurance.

 

[ban-all-sheds]

a plug like this

you could plug in .. to a socket like this

 

[mk2000]

Thanks to you all lovely people for taking time to reply on this post...

first of all i am not an electrician and do not intend to do any sort of diy electric job, luckily i can afford to pay a reasonable amount to a registered electrician for the right job.

I called 3 electrician to rewire my kitchen and all of them told me the different stories and none of them bothered to know about what power is needed for the oven and all of them assumed that oven can be run on 13a unswitched socket with 13a fused spur or 20a DP grid switch isolation on 32a main ring.

I didn't know about dedicated radial circuit is needed as per the regulation for my 3.5kw oven until checked the below post from ericmark,

(iii) connecting cookers, ovens and hobs with a rated power exceeding 2 kW on their own dedicated radial circuit

One of the electrician told me that all sockets in my house are not on main ring rather they are on radial, and its quite risky and i was so scared and the very next day i called another electrician to check the existing circuit and kitchen rewiring quote and he told me that all existing sockets are on main ring.. and i was shocked to hear this..

so i started exploring all about this not by choice.. but to have right job to be done for the right price

I have redesigned the kitchen wiring circuit with dedicated radial on 16amp or 20amp mcb with 20amp DP grid switch isolation with16 amp fuse to hard wired outlet and running another 32amp main ring for all other kitchen appliances with 20amp dp grid switches to unswitched outlets with fuse on appliances plug.

please check, if the new circuit makes any sense.

Untitled

• mk2000
• 18 Aug 2014
• 1

Thanks, MK

 

[ban-all-sheds]

please check, if the new circuit makes any sense.

It's not us to whom it has to make sense - it's your electrician.