Double oven/hob- single circuit or double

[gazdkw82]

Hi,

Friend of mine wants a new feed for double oven, however now it's a double oven and a hob.

Double oven is 7.4kw and hob is 7.4.

My Calc applying diversity is

7400/230 = 32a

32+32 = 64a (14720w)

First 10a+30% of remainder +5a for socket so

10a+16.2a+5a= 31.2a

My questions are, is diversity applied to individual items or items combined? So hob and oven seperate or together? (As you can see iv done it together)

Next question, is it advisable to run 2 seperate circuits for this or could it run on 1 circuit (with carefully selected fuse/cable)

 

[Ian1981]

On site guide suggests one circuit for 2 supplies can be used for a design current of upto 50 amps.
As long as the cooker control switch is within 2 meters of Each appliance

 

[gazdkw82]

Ok so in this case that's fine.

However if I can't apply diversity to say the hob it may be over 50amps

 

[Ian1981]

If it's an induction hob then diversity can be applied

 

[Ian1981]

 

[gazdkw82]

Yes it is so my calculations are valid?

As for isolation I plan to use a 2 DP switch with a plug as I thought it would be good to have individual control between oven and hob

 

[gazdkw82]

Just dotted these calc down. Look right?

 

[Ian1981]

Just dotted these calc down. Look right?



View attachment 37388

CCC is not 38 amps as this is for 6mm 3 phase supplies buried try 46 amps, tho you would need to apply a 0.9 cc correction factor as the tables give the ambient temp as 20 degrees Reference method D and not 30 degrees as the other reference methods are .this correction factor corrects for overload but need not be applied to a cable underground if overload is omitted say for a fixed load.
is the cable buried?

 

[gazdkw82]

Yeh it's buried, so the correction factor need not be applied?

Ah yeh I see about the CCC. It's 46A ref method D.

 

[Ian1981]

Yeh it's buried, so the correction factor need not be applied?

Ah yeh I see about the CCC. It's 46A ref method D.

Needs to be applied and there also depth to consider, ambient temperature of ground etc.
You could argue that overload isn't a factor as the load is calculated using diversity but I never personally omit overload protection for cookers.
Others might I don't.

The cable CSA you've selected 6 mm looks fine.
Only you know how it's being installed so be wary if you need to apply any more derating factors which might affect your cable CSA choice