Hardwire Oven Connection

Hi

I'm looking to replace my current oven and I'm looking for some advice as I'm a novice when it comes to DIY.

From looking into it a bit, my current oven has a 13amp fuse and plugs into a switched socket which is located to the side of the oven void. This socket has a hardwired connection for the electric hob as well (see link to Imgur page for photos https://imgur.com/a/7Rkou ).

The socket is on a separate circuit and the cable leading from the socket is a grey rectangular cable approx 13mm x 5mm. 

I understand that I can buy ovens with 13amp plugs already fitted and that these are for ovens below 2.9kW. However, if I was wanting to go with an oven above 2.9kW;

• Is it easy to determine whether the grey cable that leads to the circuit is suitable for the new use? 
  
• How troublesome/costly is it to switch the socket over if the cable is suitable?
  

Just as a note, if this can be done, I'm going to get an electrician to do the install and socket switch. 

Any help would be great!!

Thanks

The usual arrangement is the cooker switch (with or without a socket) is above the worktop where you can reach it.  This then feeds to a cooker outlet plate behind the oven / hob.

You can get cooker outlet plates with two outputs for the situation of a separate oven and hob.

Your electrician has some rework to do and he first needs to determine the cable size and see if what is there is adequate for the new load.  Sometimes it is necessary for the oven and hob to have their own separate feed.