Induction hob -diversity

[Cabbyfan]

Hi, apologies of this has been covered already...

About to sort my kitchen out, keeping the current oven which is rated at 5.4Kw. Looking to fit an induction hob which according to the manufactures data sheet is rated at 32A / 8Kw.

If I apply diversity plus 5A for socket it comes out as about 35A which leaves me wondering if its best to run in a bit of 10mm as I need to run a new cable anyway.

Anyone got any comments ? This calc assumes I can apply diversity to both appliances.

 

[JohnW2]

About to sort my kitchen out, keeping the current oven which is rated at 5.4Kw. Looking to fit an induction hob which according to the manufactures data sheet is rated at 32A / 8Kw. ... If I apply diversity plus 5A for socket it comes out as about 35A ....

Assuming that the powers are (as normal) quoted at 240V, I make that 28.75A after diversity (including the socket) at 240V, or about 28.05A at 230V.

Kind Regards, John

 

[Cabbyfan]

Thanks John.

13.4kw = 58.26A ,minus 10A and 30% of the rest gives 29A I take it ?

I was treating the 2 appliances separately hence an extra 10A

 

[JohnW2]

Thanks John. 13.4kw = 58.26A ,minus 10A and 30% of the rest gives 29A I take it ?

Yep, in round figures, that's about it.

I was treating the 2 appliances separately hence an extra 10A

I suspected that. You'll see all sorts of debates about diversity, but I think that most people who use it would apply it to the combined load. Let's face it, if it were a cooker (including oven and hob), with a stated maximum power demand (for the whole appliance), rather than separate oven and hob, I don't think that anyone would bat an eyelid about applying diversity to the total.

Kind Regards, John

 

[Cabbyfan]

Thanks again John, it's a long time since I did my 15th edition !

I'm still favouring a 10mm cable mind, it's about a 12m run and I'm only doing this job once

 

[JohnW2]

Thanks again John, it's a long time since I did my 15th edition !

It would be. I suspect that some of those in this forum weren't even born when it was published

I'm still favouring a 10mm cable mind, it's about a 12m run and I'm only doing this job once

Well, it's obvioulsy up to you, but I think most people would probably say that 10mm² was 'way OTT' (after diversity, it would, if 'clipped direct', support a maximum cooking load of 170A, plus a socket!!), that 6mm² would be more than enough and that 4mm² would actually be 'OK'. I suspect that many/most would 'compromise' on 6mm².

Kind Regards, John

 

[ericmark]

I think diversity for an induction hob is rather special. The reason I say this is the induction uses less power to cook the same food as a hot plate or halogen hob so over say 1/2 hour cooking it clearly uses less power.

But the induction hob often has the option to bring food to temperature far more rapid than any other type of hob including gas.

So in a domestic (clearly with commercial use where pans are swapped about like draft pieces this may not be true) although you could get a load of 7 - 8kW switching on all heat areas together within 2 minutes this would reduce to more like 2kW over the 4 heat areas.

I think mine has one heat area where on boost it can give 3.7kW to the pan but with anything but water it would bake the food onto the pan and the cooker also has a maximum time it will allow this to run so I would say even though my hob could in theroy use 7kW over even 5 minutes the average would be more like 3.5kW for all heat areas.

With mine boost can only be used with one ring of a pair so really you can forget about the boost function.

So my stand alone cooker rated 220 - 240V, 10466 - 12455W has a manufactures (Belling) recommendation of a 32A supply. So with 52A total load it has a 32A supply.

 

[JohnW2]

I think diversity for an induction hob is rather special. The reason I say this is the induction uses less power to cook the same food as a hot plate or halogen hob so over say 1/2 hour cooking it clearly uses less power.

That may well be true but, if so, it would presumably mean that the standard guidance diversity calculation (which has been unchanged for many years) might be fairly 'conservative' in the case of an induction hob.

Kind Regards, John

 

[ericmark]

I think diversity for an induction hob is rather special. The reason I say this is the induction uses less power to cook the same food as a hot plate or halogen hob so over say 1/2 hour cooking it clearly uses less power.

That may well be true but, if so, it would presumably mean that the standard guidance diversity calculation (which has been unchanged for many years) might be fairly 'conservative' in the case of an induction hob.

Kind Regards, John

That does seem the be the case. But I am a little careful where used commercially as I have seem how the chefs swap pans around never turning the hob off clearly when used in that fashion there would be little or no diversity. But for domestic when using 4 heat areas (rings) it does not really matter what form of hob is used the same amount of energy goes into the pan. The only thing which changes is how much waste energy goes into the kitchen. So in real terms even though the rating of an induction hob may be higher than a for example halogen hob the power used is less because less energy is wasted.

 

[JohnW2]

That does seem the be the case. But I am a little careful where used commercially as I have seem how the chefs swap pans around never turning the hob off clearly when used in that fashion there would be little or no diversity.

Indeed - but the OSG guidelines are more than "a little careful" in that respect, allowing relatively little diversity for cooking appliances in commercial environments (100% for the largest cooking appliance, {i.e. no diversity at all}, 80% for the second largest appliance and 60% for the rest).

Kind Regards, John