Designing a circuit

[1livewire]

hi

Just out of interest. Suppose a customer has an electric cooker like this one say.

The manufacturer doesn't say, The cooker is rated at x kW? (could be 12kW say for a cooker)

They give me the following information:

• Main oven energy consumption 0.90kWH.
• Top oven energy consumption 0.70kWH.

How do i design a circuit for it then? Do I

0.90 + 0.70 gives us a total of 1.6kWh of electricity used - for one hour.

Then assume the cooker could be on for 10hrs, say, in any one day, so 10x1.6kWh=16kWh of electricity for ten hours.

Using P = VI then i get 16000/230 = 70A say, now apply diversity!

The point i'm trying to make here is not to do with my mathematical ability, its my assumptions! Is this a realistic way of designing a circuit??


help please

 

[Mark.W]

No, when working with kWh, you are actually working with the cost of using the appliance.
In order to design a circuit, you need to determine how much current the appliance is going to be pulling, once that is known you can work out cable sizes, size of protective device etc.

Regards
Mark

 

[Steve1412]

Seems a sticky one that. Why don't they just tell you the power rating.
I could be wrong but I can't see how you can calc the total power required from the information given.
Its okay them saying it takes 900 watts per hour but this is basically an average of the time the element is actually energised.
It may well be a 6kw element but due to the insulation properties of the oven is only energised for 9 minutes per hour which equates to 0.9kwh.
It may well be a 3kW element which is energised for 14 ish minutes again roughly 0.9kwh.

 

[1livewire]

No, when working with kWh, you are actually working with the cost of using the appliance.
In order to design a circuit, you need to determine how much current the appliance is going to be pulling, once that is known you can work out cable sizes, size of protective device etc.

Regards
Mark

...ah, thanks. Just to clarify then, would the relevant information be included on (or with) the unit somewhere?

 

[Mark.W]

Yes, normally when you buy an appliance like a cooker, it will come with a booklet. The power rating should be in that booklet, or it could be on a sticker at the back of the appliance.

 

[1livewire]

Yes, normally when you buy an appliance like a cooker, it will come with a booklet. The power rating should be in that booklet, or it could be on a sticker at the back of the appliance.

seems obvious, but i had to ask, thanks again!

 

[Spudnik]

Most built in ovens and some freestanding, have the rating label on the inside of the door frame of the main oven.

Or If you have the model number you can check the makers websie.

Or, you can just put in a 10mm and be done with it

 

[1livewire]

Most built in ovens and some freestanding, have the rating label on the inside of the door frame of the main oven.

Or If you have the model number you can check the makers websie.

Or, you can just put in a 10mm and be done with it

the third option sounds good.......lol

 

[the jock]

what you all seem to have missed is that a main oven will have a 2kw - 2.5kw element
add to this 1.8 kw for top oven/grill
add to this 6-7 kw for the rings

take diversity into consideration

fit a 10 mm cable somebody has worked it all out before use their exp.

 

[Mark.W]

what you all seem to have missed is that a main oven will have a 2kw - 2.5kw element
add to this 1.8 kw for top oven/grill
add to this 6-7 kw for the rings

take diversity into consideration

fit a 10 mm cable somebody has worked it all out before use their exp.

What have we missed? now I'm missing something!

 

[michaelw6]

you can always take out the elements.... no thats not a constructive idea is it.
just put in a 10.mm i have not fitted a household oven with any more that that as its feed cable b4.

 

[xraytek]

...ah, thanks. Just to clarify then, would the relevant information be included on (or with) the unit somewhere?

You will probably find all the information you need in the equipment manual including recommended minimum mcb & cable size.

Here is a usefull link for finding manuals