wire size for cooker AND hob

[adam10]

Hi, I am building a new extension including a new kitchen but this will not be ready for many months. With impeccable timing my current cooker has died Fortunately I have been given an oven (7.2kW rated) and a separate hob (6.4kW rated) to tide me over. Since this installation will be temporary i was wondering if I could run a single 10mm cable to power both units (20m from consumer unit) then reuse the cable for wiring a new oven into the new kitchen when the time comes. i only have one spare space in the consumer unit so wiring 2x 6mm cable is not really an option. I'd be very grateful for any ideas and assistance - there is only so much salad a man can take! Thanks

 

[sparkticus]

Your total load is 13.6KW which is roughly 60 amps at 230 volts.

10mm CSA cable clipped to a wall is good for about 64 amps so you are ok there. Voltage drop will also be fine at about 2.5%.

In reality a diversity factor can be applied to a cooker load since it is not likely that it will switch-in all loads at the same time for continuous periods.

It will be fine. However as a long term solution I would go with two separate supplies, one for the hob and one for the cooker. That is just a personal choice based upon experience. I take on board that you only have one spare way at your consumer unit but adding an additional CU does not have to be expensive.

 

[echoes]

If the current cooker supply from the CU is 32A / 6mm² that would also be OK with diversity for your oven + hob, but close to the limit.

 

[adam10]

Thanks guys, I really appreciate your help on this.

 

[ban-all-sheds]

Hi, I am building a new extension including a new kitchen

Properly designed, the new kitchen will need new circuits.

i only have one spare space in the consumer unit

So as you've got an electrician involved anyway, now would be an ideal time to have him replace the CU in readiness.

 

[adam10]

Thanks for response.
Fear not - the new kitchen will get new circuits - as will the whole house.
CU will also be moving and replaced with bigger one. Until then I'm trying to keep the old house working - hence the need for the temporary solution.

 

[ban-all-sheds]

The moving part might make it more awkward, but often the way to deal with this sort of situation is to install the new, larger, CU in addition to the existing and begin to use it for a few circuits, then later transfer all the others.

 

[THRIPSTER]

If it were me, then I'd use diversity calcs to assess the total demand at the head only but would still size cables to the appliances based upon maximum possible demand - am I wrong?

Regards

 

[sparkticus]

If it were me, then I'd use diversity calcs to assess the total demand at the head only but would still size cables to the appliances based upon maximum possible demand - am I wrong?

Experience tells me to be very careful about diversity in a domestic environment. Many people work from home these days and we live in a 24 hour/7 day world where just about anything that can be turned on and often is turned on and for long periods. A cooker has a natural diversity in the sense that the various heating element temperatures regulated by the thermostats will almost certainly not all be on at the same time and if they are then not for very long. Some modern cookers don't use conventional on/off thermostats they use a thermistor and electronic phase angle control (often a TRIAC) which provides a more even temperature control and therefore a more even load. I would always size a cooker supply based upon its maximum load. If the combined oven and hob were more than about 10 KW then I would make it two separate supplies especially if the house was being rewired.