Jaime wrote:

As I said this is the problem, what link in the chain prevents this. I

fidn

it odd as theres cookers are quite popular and so are electric showers

so

surely theres some kind of preventative feature in the chain.


The Regs allow you to apply diversity in a situation such as this, in
the specific case of a domestic electric cooker, you take the first 10A
of the total load, then add 30% of the remainder, plus another 5A if the
control unit contains a 13A socket. So, if the total load of the cooker
is 67A, then the circuit needs to be rated 10A + (0.3 * 57)A = 27.1A. so
a 32A MCB will be fine (at a pinch even if there is a socket in the
control unit) and in most normal circumstances 6mm^2 cable will also be
fine. The reason for this is that each heating element will have its own
thermostat, all of which will cycle 'out of sync' so the full load in
practice is unlikely to be drawn for anything other than a very short
time.


Thanks very much thats exactly the information I was looking for.


You rate the MCB not on the cooker load, but on the grade of cable going
to it. The purpose of the MCB is to prevent cables catching fire, so if
its decent grade cooker cable 45A or 50A MCB is in order.



Regards

Jaime