Breaker for separate oven and hop

[KenB]

My question is similar to this one I found:
//www.diynot.com/forums/viewtopic.php?t=36208&highlight=hob
but there was no conclusion.

I have an elecric oven and gas hob, and want to replace the gas hob with an electric one.

+ Current the single oven is on a 32A breaker. The oven is being replaced with a double oven that suggests a 40A breaker.

+ The new hob is 6.3 KW.

+ I'm am not sure of the wiring used for the existing oven so plan on replacing it with 6mm wire rated to 12 KW to ensure it is correct. The new wire is stated as being suitable for ovens and showers.

+ The oven and hob will be within 2 meters of the switch. The switch as it happens is also within 2 meters of the breaker.


Now if I have both ovens and all four hob rings on by my calculation I will have just over 12 KW so a 50A breaker is on the limit.

Questions:
+ Can I have both cooker and hob on the same wire from the same switch and to the same breaker? Previous questions/answers on this forum seem to suggest yes but it seems marginal to me.

+ What size breaker should I use? Is it ok to have a 50A breaker if I only have the oven on and not the hob?

Thanks for any advise.

 

[Steve]

One thing i can see straight away - you need a 10mm² cable.

6mm² can not carry 50amps and is not rated to any amount of power, it is rated to a current, 47A i think, when clipped to a wall with no insulation. And it is always better to over-specify when designing circuits

However, a 50 amp breaker can be used with the load you describe as long as you use 10mm² cable. When do you ever have both ovens and all the hob rings on at once? Hardly ever would be my guess.

Will your consumer unit take a 50A breaker? Show us a picture and we will tell you

 

[Adam_151]

Install two 10mm² circuits...

 

[KenB]

Hi Guys,

Thanks for the fast response!

I agree two separate circuits is the thing to do. Mrs KenB will have to put up with two switches

10mm cable would also seem worth while although over spec if wired separately.

Having just read this:
http://www.house-signs.co.uk/info/electrical-safety.html
it seems I shouldn't be doing this myself any more anyway. I need to research this more but comments would be good. Do I really have to get someone round from building control to check what I have done?

 

[Steve]

yes you need to inform building control what you are doing, they will take much interest in this. They will test and certify your work (they cannot make an extra charge on top of their standard charge for this) Called part p of the building regs. search for it on here. alternatively see ban's explanation of part p (read the entire post made by ban)

 

[Adam_151]

This work is notifiable under part p, you can either have an electrician who can self cert do this work for you, or you can pay building control your fee and tell them what you are doing 48 hours in advance, do the work, and they should send someone round to make sure its all correct, but they like to mess around, you'll probably be told you have to find an electrician willing to fill in the inspection and testing part of an EIC at your expense..., as well as paying them, the silly beggars that they (building control) are... I'll leave ban-all-sheds to take it up from here, this is his speciality

If it was me tho I'd just do it anyway (making sure I did it properly though, of course ) ...but I can't advise you to break the law