Wiring a double oven and separate hob

[kirton]

Hi,

I am about to wire in a new electric hob 7.1 kw and a separate double oven 5.4kw.

My old oven is 11kw and was hard wired into a 40 amp fuse spur.

I have been told my hob 7.1 kw should be wired into this, with it's own isolator.

I have a normal 13 amp plug socket for the new oven (5.4kw) as I was told all new ovens can plug into normal sockets. This socket also has it's own isolator switch.

I have since been told this is incorrect and it should be hard wired into the same socket as the hob, and it's ok to share the isolator switch.

Can anyone tell me which is correct please?

Thank you

 

[industryspark]

7100 watts / 240 volts =29.6A
5400 watts / 240 volts = 22.5A

total is 52.1A ish........

so the 40A mcb you have is not suitable for wiring both into the same point as it is likelly to trip should you have a lot of the hobs rings on and the cooker raging away (think xmas day)

the 5.4KW oven cannot be put on a 13A plug top for the obvious reason shown above.

 

[Taylortwocities]

What, no diversity?

 

[kirton]

Hi,

Thank you Industry spark for your reply.

Not what I wanted to hear, but there you go.

I am guessing I need my electrician to redo the plug socket he fitted for a 40 amp fuse spur?

The problem I have is that my units are all in now, does this mean, holes in my new ceiling to pull new cables through? Or can they increase the fuse to a 45 amp? (still slightly under I know, but would this be allowed?)

With the help of your calculations my husband worked out our old cooker 11kw with our old circuit which I believe was 32amp, and this was well over. Although in 7 years we never experienced any problems.

Thank you Taylortwocities for your reply, but what does "diversity" mean?

As I said I am not experienced with electrics.

Thanks again for the replies.

 

[industryspark]

diversity means in laymans terms that you allow for the fact that the cooker and hob (in this case) may not need full power at all times.......i.e you may not need all rings on at same time as cooker, ect.

in this case you may be ok to have both appliances running from the existing point because as stated you may not need full power all at same time (therefore not going above the 40A 'limit' of the mcb).......... but then again you may find you get nuisance tripping of the mcb should you have everything running at the same time which is why i said maybe its not suitable, but again this depends on what is going to be running at any one time.

you may find you get away with it (as with your old cooker if i read your post correctly).

can you clarify what the circuit actually is?

is it a fuse in your consumer unit or an mcb (circuit breaker)?
do you know the cable size for the circuit? 6mm perhaps?
length of run and where the cable passes through?

 

[kirton]

Hello again,


The 40 amp circuit breaker is inside the consumer unit (mcb ?) with a 6mm cable traveling approx 12m to an isolator switch with a further 2 m to the box which the appliances would be wired into.


Another thought, is it possible to up the circuit breaker to 45 or 50amp ?

Thanks again