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Topic Title: 17.6 kw
Topic Summary: oven & hob
Created On: 23 July 2013 08:13 PM
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 23 July 2013 08:13 PM
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Ampman

Posts: 1021
Joined: 06 February 2006

17.6 KW .

Induction hob & oven .

Im thinking running 10 mm cable .

Can i apply diversity to induction hob ?
 23 July 2013 08:29 PM
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OMS

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You can, but I wouldn't apply much as the boost function can extend for some time on an induction hob.

What does the manufacturers data say ?

Regards


OMS

-------------------------
Failure is always an option
 23 July 2013 08:54 PM
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Ampman

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I aint got manufacture instructions , cant find a download sheet .

Its a Professional rangemaster plus 110
 23 July 2013 10:58 PM
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M.Joshi

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Is this the manual you are after:

http://www.manualslib.com/manu...c.html?page=24#manual

If so, have a look at page 24.

-------------------------
M.I.E.T - Forfeited this due to The I.E.T's ridiculous membership rules!
 24 July 2013 07:38 AM
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SherlockOhms

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100mA RCD?

Best make sure the CCU doesn't have S/O.

S.
 24 July 2013 09:26 AM
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ebee

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Antric`s post might have some relevance here

http://www.theiet.org/forums/f...id=53500&enterthread=y

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 24 July 2013 07:41 PM
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weirdbeard

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Originally posted by: ebee

Antric`s post might have some relevance here



http://www.theiet.org/forums/f...id=53500&enterthread=y


Hi Ebee, antric says he doesn't think that diversity can be applied.... in the OP's case thats 76 amps..... that would need a 25mm flex between the outlet and cooker! Also if the page of the MIs that m.joshi linked to is the correct document it says that the maximum conductor CSA for the cooker terminals is 10mm?

Compared with standard electric hobs I was under the impression that induction hobs were more efficient, so I would have thought this efficiency could also follow through to the supply cabling sizing.

If you take a snap shot of one hours heavy use for the same meal,as it's more efficient, the induction cooker should put less thermal stress on the supply cable than the same amount of food cooked on a standard electric cooker?
 24 July 2013 07:47 PM
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weirdbeard

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Originally posted by: SherlockOhms

100mA RCD?



Best make sure the CCU doesn't have S/O.




....and that the cooker circuit is wired in 16mm swa or similar, if no diversity and the customer doesn't like trunking or surface clipped T+E!
 24 July 2013 09:49 PM
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antric2

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What rating is the hob and what rating is the cooker.

I agree with what weirdbeard has pick up on with my comment but 17,5kw seems big draw and this job may be an exception to normal demand and may need splitting of supply, a supply for each appliance.
Most of the hobs and ovens we fit are approx 7kw ind hobs with a 3kw or 4.2kw double oven so can use 10mm supply with 6mm load cables.
I will try to find the piece on Ind hobs and diversity that I read.
Regards
Antric
 25 July 2013 12:40 AM
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geoffsd

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Originally posted by: antric2
Most of the hobs and ovens we fit are approx 7kw ind hobs with a 3kw or 4.2kw double oven so can use 10mm supply with 6mm load cables.


4mm would do with 32A MCB.

7 + 4.2 =11200 /240 = 46.7 -10 x0.3 +10 = 21A

Oh, 2.5mm with 25A MCB but that would be silly.

A lot of over-engineering goes on these days.
 25 July 2013 11:04 PM
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antric2

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Originally posted by: geoffsd

Originally posted by: antric2

Most of the hobs and ovens we fit are approx 7kw ind hobs with a 3kw or 4.2kw double oven so can use 10mm supply with 6mm load cables.




4mm would do with 32A MCB.



7 + 4.2 =11200 /240 = 46.7 -10 x0.3 +10 = 21A



Oh, 2.5mm with 25A MCB but that would be silly.



A lot of over-engineering goes on these days.



Evening Geoffsd,
Applying diversity in normal cookers and hobs,you are quite correct but what about the Christmas day scenario and the way Induction hobs use their boost function.
Is it not better to over engineer in this situation than not?
Regards
Antric
 25 July 2013 11:38 PM
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AJJewsbury

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the way Induction hobs use their boost function

Check the manual for yours - I'm pretty sure the ones I looked at "boosted" one ring by stealing power from another - overall consumption unchanged.

For the Xmas day scenario we still have the thermal equivalent current string to our bow - drawing 30A or even 40A for as long as it takes to bring a pan of sprouts to the boil won't warm a cable (or fuse or thermal element of an MCB) as much as a continuous 20A.

- Andy.
 25 July 2013 11:48 PM
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sparkingchip

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and we don't want to burn the pigs in blankets.
 25 July 2013 11:48 PM
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sparkingchip

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and we don't want to burn the pigs in blankets.
 26 July 2013 12:05 AM
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geoffsd

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Originally posted by: antric2
Evening Geoffsd,

Applying diversity in normal cookers and hobs,you are quite correct but what about the Christmas day scenario and the way Induction hobs use their boost function.

Regards

Antric


Dear Antric2,
Good evening to you.

I note you say that I am quite correct, therefore ...

I am a firm believer that the Christmas Day scenario is folk lore.
Would anyone contradict with multiple cases reporting this happening?

I can find no details to verify but logically I would suspect that the boost function is included in the given rating of the plate/hob.
After all, it would be illogical to state the rating of a plate is, say, 2kW without stating that it increases to 2.5kW on boost.
More likely, it runs at perhaps 1.5kW and increases to the 2kW on boost.

Also, as has been said before the induction hob is promoted as being more efficient than other methods. By definition, this means it uses less power.
It could use a lesser total amount of power in a shorter time but even so heating to the same temperature more quickly will not increase the maximum load at any given time and once to temperature the cooking will take the same amount of time but using less power.
I do not see why diversity cannot be used with these appliances.

There is a lot less wasted heat with induction hobs.

Is it not better to over engineer in this situation than not?

That depends what you mean by better and what the reason is.
If the circuit complies then what benefit is there?


If I am wrong about any of these points I should like to know.

Yours sincerely,
Geoffsd.
 26 July 2013 07:13 AM
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zeeper

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4mm would do with 32A MCB.

7 + 4.2 =11200 /240 = 46.7 -10 x0.3 +10 = 21A



Oh, 2.5mm with 25A MCB but that would be silly.



A lot of over-engineering goes on these days.




You do not use the above formula to work out the csa of the conductors for the cooker supply cable.

I suggest you read the first sentence of appendix A, in the on site guide. Page 109
 26 July 2013 08:14 AM
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ebee

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Zeeper,
So what I think you`re saying is, for our example (working on 240v not 230v in this case) is.

Cooker circuit protective cable and fuse must be selected for 46.7 amps or more and not for 21 amps.

However the 21 amp figure (along with the diversified figures of other such circuits ) may be used when calculating cable and upstream device such as tails and cutout.

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 26 July 2013 11:32 AM
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zeeper

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Cooker circuit protective cable and fuse must be selected for 46.7 amps or more and not for 21 amps.

However the 21 amp figure (along with the diversified figures of other such circuits ) may be used when calculating cable and upstream device such as tails and cutout.



Yes ebee, thats the way I see it with reference to the OSG.

In this case the diversity of 10A +30% and 5 amp for intergrated socket are for determining maximum demand for the installation.

And not for assessing the required CSA of the cooker conductors
 26 July 2013 12:08 PM
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daveparry1

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I think you've got that wrong! The first 10 amps plus 30% of remainder plus 5 amps if there's a socket diversity calculation is intended for domestic cooking equipment,

Dave.
 26 July 2013 02:16 PM
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zeeper

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I think you've got that wrong! The first 10 amps plus 30% of remainder plus 5 amps if there's a socket diversity calculation is intended for domestic cooking equipment,


Yes that is correct well spotted.

I didnt think I would need to over elaborate to much in my answer for the forum members. As they would know what I was suggesting. But maybe in this case I under stepped the mark.
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