Cooker + Hob

[walec]

Hello all,

Need a little help here, never done seperate hob an Oven before.
Just been asked to look at a job for a friends Dad who was brought a ground floor flat.
He has taken out his old cooker and wants to replace it with a seperate Oven and Hob.
Oven - 2.1KW
Hob - 6.6KW
It is fed by to a cooker switch with 6mm cable with a 30A breaker (board is early 80`s)

If I feed from the cooker switch (no socket) to a JB can I connect both?
The Hob pulls 28A and the Oven 9A, Thats 37A on full load, working out diversity its 28A.
So I am thinking should I spur off the kitchen ring for the oven with a 13A plug or fused spur.

As he also wants to replace his shower and change a shaving socket to a light over the sink
I have suggested a new board with RCD as there is no RCD at present but he says he can not
afford it. I am going to have to put a seperate RCD in here anyway, special location etc.
There is little room to do much beacuse of all the storage heating controls. All hidden in a broom
cupboard.

Any help much appreciated

 

[Mac]

Hello all,

Need a little help here, never done seperate hob an Oven before.
Just been asked to look at a job for a friends Dad who was brought a ground floor flat.
He has taken out his old cooker and wants to replace it with a seperate Oven and Hob.
Oven - 2.1KW
Hob - 6.6KW
It is fed by to a cooker switch with 6mm cable with a 30A breaker (board is early 80`s)

If I feed from the cooker switch (no socket) to a JB can I connect both?
The Hob pulls 28A and the Oven 9A, Thats 37A on full load, working out diversity its 28A.
So I am thinking should I spur off the kitchen ring for the oven with a 13A plug or fused spur.

As he also wants to replace his shower and change a shaving socket to a light over the sink
I have suggested a new board with RCD as there is no RCD at present but he says he can not
afford it. I am going to have to put a seperate RCD in here anyway, special location etc.
There is little room to do much beacuse of all the storage heating controls. All hidden in a broom
cupboard.

Any help much appreciated

No you can't mate,anything over 2KW has to have it's own dedicated circuit.What happens on Xmas day when everything is going full load.Just use RCBOs on the circuits that need protected and note it on the cert.If the customer doesn't want the CU changed,you can only advise and note it again on the cert.

 

[walec]

Thanks Mac,

Just so I understand, I need a circuit for the cooker and a circuit for the hob?
If thats the case this is not good news as it is a ground floor flat and the bathroom is between the
kitchen and the board, which is also on the far wall!
I don`t think I will be able to get a RCBO to fit this board, its an old ceramic Crabtree with MCB`s, what do you think of putting a RCD main switch in before the board, I saw this recently, I was not sure but from the feedback received it conforms.

 

[Mac]

Thanks Mac,

Just so I understand, I need a circuit for the cooker and a circuit for the hob?
If thats the case this is not good news as it is a ground floor flat and the bathroom is between the
kitchen and the board, which is also on the far wall!
I don`t think I will be able to get a RCBO to fit this board, its an old ceramic Crabtree with MCB`s, what do you think of putting a RCD main switch in before the board, I saw this recently, I was not sure but from the feedback received it conforms.

Main RCD switch is ok if the customer won't pay for an upgrade.How old is the installation.When you replace MCBs/rewireable fuses with RCDs,this is when the problems start.

 

[andyb]

One supply can feed two cookers up to I think 50amps.

 

[Mac]

One supply can feed two cookers up to I think 50amps.

On a 6mm cable,you are jestingSeparate supplies mate

 

[flukey]

from memory you can supply 2 items from the one switch as long as theyre no more than 2 metres from it. will look in the book later

 

[Mac]

from memory you can supply 2 items from the one switch as long as theyre no more than 2 metres from it. will look in the book later

No worries mate.How many CUs are within 2 metres of the kitchen.Me personally would still run separate supplies for each appliance.Good practice in the long run

 

[flukey]

No worries mate.How many CUs are within 2 metres of the kitchen.Me personally would still run separate supplies for each appliance.Good practice in the long run

didnt mention cu mac, said switch (cooker isolator)

 

[Mac]

Sorry mate,my mistake

 

[Deleted member 9648]

I dont see any reason why the oven (2.1 kw) cant be plugged into a single socket wired onto the kitchen ring circuit, PROVIDED it is a dedicated kitchen ring...and other heavy loads are taken into account, ie washing machine etc. I also dont see any reason why the existing cooker circuit cannot supply both appliances,but I wouldn't use a JB. A better arrangement would be to split the cooker lead coming from the isolator with a fixed adaptable box and large flex glands to secure the cables.A 6.0mm (will be fused at 32a) could feed a single socket to plug the oven into. Fully agree that if dedicated circuits can be installed so much the better,but with the loadings of the appliances given by Walec I dont think i'ts worth major upheaval to achieve.

 

[andyb]

On a 6mm cable,you are jestingSeparate supplies mate

No Mac, I'm not for one second sugesting you run 50 amps on 6mm cable,
I'm just quoting the regs which say that a cooker circuit can supply two cookers up to a rating of 50 amps.
Of course all the other factors would need to be in place such as cable size, procetive device, reference method etc etc.

 

[sparks1234]

I dont know how this works in a physical way as in where your switches etc are but you could install a cooker switch with integral socket, that would cover what you need

 

[walec]

Guys, Thanks for all your comments, the guy is on hoilday now until Monday, I will re-visit and take another look, I have just read in the Electricians Guide to the building regs (Green Book) that a lightly loaded oven of 13A or less may be connected into a ring final circuit. I will asess again though and let you know what I do. Cheers

 

[Spudnik]

Personally i dont see a problem with connecting the 2 cooking appliances to the existing circuit.

The 6mm cable is rated above 30Amps and the diversity brings the load within that.

This work would not need certifying or notifying as no work is being done on the fixed wiring.



Having said that, I would carry out a few quick tests on the circuit to make sure everything is in check, mainly for peace of mind.

It would be better to have a 40A circuit installed, however as long as the client is aware of the possible problems.