Replacement Hob Question of Available KW Load

[src1]

The double oven and separate electric hob share a 40 amp supply. I believe this to be on a 6mm cable rounding the distance up to 15 metres through the walls. Both have their own individual fuses with an available socket, this is not used. The double oven is 5.4kw. The separate electric hob is 5.9kw. The hob needs to be replaced and we are considering an induction hob but first we need to understand what our limitations are for the replacement hob. Upgrading the wiring could be a real pain and may not be an option. So I would appreciate a little advice on the total kw load that I can consider for the replacement hob.

While I’m currently looking at electric and induction hobs I see that some share the same kw loadings so in this case I guess that any decision is between an individual’s preferences rather than electrical loading.

 

[winston1]

Any domestic hob can be used. 4mm cable on a 32 amp circuit is quite OK. Who ever did your setup wasted money and the planets valuable resources of copper. Google diversity.

 

[ban-all-sheds]

Both have their own individual fuses

What does that mean?

 

[src1]

Really appreciate the swift response, this is my first post regarding this job so the advice and guidance is a great help, thankyou!

Apologies my comment "both have their own individual fuses" was incorrect, I should have said the double oven and electric hob both have their own red off switch with a plug socket that is wall mounted near the appliance.

Both share the same 40 amp from the fuse board.

I have just been looking at Siemens EH645FEB1E induction hob, although this has a total KW7.4 rating its also has a 20 amp rating and fits straight into the worktop. https://www.johnlewis.com/siemens-eh645feb1e-induction-hob-black/p3255902

 

[JohnW2]

Because of the concept of 'diversity', which takles into account the fact that all parts of cooking appliances will not simultaneously be drawing their maximum current for appreciable periods of time, a 32A circuit can support up to a total of about 19kW of cooking appliance loads, and a 40A one nearly 24kW total.

Kind Regards, John

 

[src1]

Thanks Winston1, Ban-all-sheds and John much appreciated, i will take some time as I look into this a little more and will probably return to pop a few more questions.

 

[ban-all-sheds]

the double oven and electric hob both have their own red off switch with a plug socket that is wall mounted near the appliance.

OK.

FYI, if you are ever having a new kitchen and associated upheavals, those switches are not mandatory, so if you don't want them you can get rid of them.

Both share the same 40 amp from the fuse board.

As others have said, cooking appliance circuits are not designed on the basis of the theoretical maximum load, because once an oven or hob zone is up to temperature it switches off, and then cycles on/off to maintain the required temperature. A heating element is not "dimmed" like a light is - it is either 100% on or it is off, but averaged out the load is assumed to be a lot less than the maximum.

You can read about it here: http://www.tlc-direct.co.uk/Book/6.2.1.htm

I have just been looking at Siemens EH645FEB1E induction hob, although this has a total KW7.4 rating its also has a 20 amp rating

And there you have it.

7.4kw @ 230V is 32A

30% of 32A + 10A = 19.6A

Even though your oven is separate I would say you do the diversity calculation on the total, i.e. 12.8kW -> 26.7A. You're supposed to add 5A for the socket, so even accounting for your two that's 37A, i.e. within the circuit limit.

and fits straight into the worktop. https://www.johnlewis.com/siemens-eh645feb1e-induction-hob-black/p3255902

The only thing I would advise about that is that you consider the practicality of touch controls, and controls built into the hob like that.

Firstly, to adjust any "ring" you have to first select it, and then start swiping your finger. That is nowhere near as fast as having dedicated knobs which can, if necessary, be twiddled two at a time.

Secondly, you might have problems accessing the controls in the first place. This is how that hob would play with my largest pan in use:

Rather impractical.

IMO, designs like that are a triumph of trivial cosmetic appearance over sound functionality.

 

[EFLImpudence]

7.4kw @ 230V is 32A

30% of 32A + 10A = 19.6A

Even though your oven is separate I would say you do the diversity calculation on the total, i.e. 12.8kW -> 26.7A. You're supposed to add 5A for the socket, so even accounting for your two that's 37A, i.e. within the circuit limit.

You forgot to deduct 10A first. Doesn't make a huge difference.

16.7 & 23.7

 

[ban-all-sheds]

I did indeed.

 

[Taylortwocities]

the double oven and electric hob both have their own red off switch with a plug socket that is wall mounted near the appliance.

I am sorry, me no understand this. What do you mean by a "plug socket".
I'm not being pedantic about terms. What DIYers call a plug socket is really a socket like this

into this goes a plug

and this has a fuse in it, maximum size 13amp.

13amp is not big enough for the double oven or for the proposed hob.
Can you describe what you mean. Or take a photo of what you have that connects the appliances to the power.

 

[ban-all-sheds]

You forgot to deduct 10A first. Doesn't make a huge difference.

Ah, but did I?

What is the guidance formula in the OSG?

 

[Taylortwocities]

.....or do you mean that each appliance has one of these

with the appliances being directly connected to some sort of connection plate?

 

[EFLImpudence]

I should have said the double oven and electric hob both have their own red off switch with a plug socket that is wall mounted near the appliance.

 

[Taylortwocities]

Are there two of thesse then, or one for both appliances?

 

[ban-all-sheds]

I am sorry, me no understand this.

Really?

What do you mean by a "plug socket".
I'm not being pedantic about terms. What DIYers call a plug socket is really a socket like this

Yes, a socket for a plug.

Not a socket for the head of a bolt.

Or a socket for the end of a ball on a bone.

Can you describe what you mean. Or take a photo of what you have that connects the appliances to the power.

I really am so looking forward to the fun that will ensue when you try to claim that you really had no idea that he meant something like this:

Please don't wait too long, as I need to get to bed.