Cooker wiring

[sterod1971]

This may be in wrong forum, aplogies if it is from a newbie.

Right I have a neff 3640 and the instructions are rubbish! I need to wire in the ovens. The ovens are rated at 4.5kw which I understand is around 20 amps. There is no electrical connection for the cooker. there is a plug socket nearby which is connected to 2.5 twin and earth. I understand from cruising around the variious cable sizing calculators on the web that 2.5mm cable is good for 20 amp.
So can I change the double socket for a cooker conection and leave it be. Or would I need to run a radial circuit in 6mm back to the consumer unit from a 45 amp cooker switch. then run cable from the switch to a terminal box, then connect the cooker to the terminal box. There is no spare MCB on the consumer unit (damn) so would I have to upgrade the consumer unit too? This would have to all surface mounted and clipped. The run is about 10 meters

 

[Chri5]

Why post twice ??????????????????

A ring main can't be used- so lets not go there.

4500 w / 230 v = just under 20 amps.

Use a 6mm TE cable for the run and the cable rating is about 30 a, so a bit over designed.
Use a 4mm TE cable and the rating is 26 a
Use a 2.5 TE cable and the rating is 21 a, so too near to the required demand to use.

As you know, new circuits and working in kitchens are both notifiable under Part P

 

[sterod1971]

Why post twice ??????????????????

Cause I is Fick!

A ring main can't be used- so lets not go there.

4500 w / 230 v = just under 20 amps.

Use a 6mm TE cable for the run and the cable rating is about 30 a, so a bit over designed.
Use a 4mm TE cable and the rating is 26 a
Use a 2.5 TE cable and the rating is 21 a, so too near to the required demand to use.

As you know, new circuits and working in kitchens are both notifiable under Part P

Thanks. The double socket in question is a radial direct from the consumer unit. I had hoped that it was originally a cooker circuit but furthur investigation proves it to be 2.5 twin and earth.

I suspected that 2.5 was too close to comfort

Divergence factors were never mentioned during part P training!

So i'll be running a new radial circuit back to the consumer unit in 30amp, is it ok to run it in plastic square conduit? will it be necessary to install a cooker switch as well?