Cooker / Hob Wiring Question

[richardg]

Hi

Our house is a fairly modern property built 25 years ago. The wiring for the double oven and separate hob is 6mm cable protected by a 32amp breaker at the consumer unit. At the moment, the 6mm cable goes into a 45amp cooker switch (no plug) and then to a 45amp junction box. This junction box feeds the oven and the hob. This configuration has worked quite happily over the years.

We are now replacing the oven and the hob with similar units. The new oven has a rating of 20amps (3.95kw) and the hob has a rating of 30amps (7kw). I would also like to move the hob to the opposite side of the kitchen, a distance of 5 metres around the wall. My initial plan was to put in an extra cooker switch (no plug) next to the hob and run 5 metres of 6mm cable below the work surface.

I have read many posts on this forum and I have also read The Which Book of Wiring and Lighting. The Which book states that 6mm cable is normally recommended for cooker circuits. However, I am concerned that the extended length of the cooker circuit (I would estimate a distance of 15 metres from the hob to the CU) means that the 6mm cable is not big enough.

I would like to avoid the need to run another cable back to the CU, especially as the wiring seems fine for the existing units but as I intend to get this work certified for Part P, I want to do this properly.

Any advice would be greatly appreciated.

Thanks.

 

[Adam_151]

I'm afraid that to do this properly you will have to run a cable back to the cu, because you need to install another circuit for the hob, use 10mm cable for future proofing, and go from a 32A breaker in the cu, to a cooker switch, to the cooker outlet plate, to the hob. Also change the breaker on the existing cooker circuit (which now supplies just the oven) to a 20A one. All breakers should be type B

 

[richardg]

Thanks Adam. It was one of those questions that I suppose I already knew the answer to. I will now re-think the work that needs to be done.