UK Need help with cable size and breaker size

[Uplight99]

I’m still an apprentice electrician so the whole thing around diversity is still a bit confusing to me

A family member has moved into a new flat. The existing cooker circuit is 6mm on a 32A MCB. She has bought a cooker which pulls 9.6Kw.

I know you do 9600/230 = 41.7

This is telling me that a 32A isn’t going to suffice for this, or am I wrong?

I am going to recommend to her that I rewire the cooker supply in 10mm and put it on a 40A MCB. Is this correct? If not, if someone could break it down to me how you work out the diversity it would be appreciated

 

[James]

Check out the manufacturers instructions for recommended supply.

 

[newfutile]

Diversity can be applied to cookers as there on thermostats , once they reach the set temp they turn off until its cooler than set temp when they turn on.
Therefore we can apply diversity as follows: Cooking: 10A + 30% of cooker full load above 10A and + 5A if there is a cooker socket

10+(30% x 31.7) 9.5 = 19.5 amps +5 amps if you have a cooker socket =24.5 amps

 

[pc1966]

It is probably OK as unlikely they would turn on everything at once. That 42A max on a 32A MCB would trip somewhere between around 1 and 10 minutes so there is a sporting chance that the thermostats would have started acting and reducing the average current to something closer to the diversity rating.