What kW is this oven/hob?

HappyHippyDad

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• Oct 8, 2021

• #1

Customer has a smeg sy921px8 symphony.

On line it looks like it is 15.8kW, but if you look at the rating plate in the picture it looks like it is less than this!

In the picture it has a squiggle then says 12.5kW. Is this the total rating of both oven and hob? Just seems weird it has the hob rating, then total rating but not oven rating.

The reason for the enquiry is relating to the cable size I will be using, 6mm or 10mm.

 

Rockingit

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• Oct 8, 2021

• #2

Even if it's 'only' 12.5kw you're into 10mm cable anyway so not sure of the dilema?

 

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Dustydazzler

• Oct 8, 2021

• #3

Whack it on 10mm cable , better to over size than under size

 

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• Oct 8, 2021

• #4

I think the difference in rating is due to the Booster function.
I'm not sure if it's a Smeg thing or whether it came up on a different make, but has been discussed before, an owner was complaining about the reduction.
Although the Booster can add 2.2kw to the front left hob I believe it does it by reducing power elsewhere if the Hob / Oven is in full use, so the max use never exceeds 12.5kw.

 

7029 dave

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• Oct 8, 2021

• #5

IMO the total rating is 12.5Kw, 10mm cable

 

telectrix

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• Oct 8, 2021

• #6

6.0mm cable ref.C has been fine upto 15kW for donkeys, allowing for diversity. never even hots up a 32A MCB above warm.

 

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Rockingit

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• Oct 8, 2021

• #7

telectrix said:

6.0mm cable ref.C has been fine upto 15kW for donkeys, allowing for diversity. never even hots up a 32A MCB above warm.

Click to expand...

6mm rated to 46A - 12.5kw being 53ish. Totally agree with you practically, however.

 

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Dustydazzler

• Oct 8, 2021

• #8

You could probably shove 100a up a 6mm and it wont even bat an eyelid

But following the regs for a 12kw load i would fit 10mm

 

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IAmSparkytus!

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• Oct 8, 2021

• #9

Dustydazzler said:

You could probably shove 100a up a 6mm and it wont even bat an eyelid

But following the regs for a 12kw load i would fit 10mm

Click to expand...

Whats your thinking behind your first comment out of interest?

 

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• Oct 8, 2021

• #10

telectrix said:

6.0mm cable ref.C has been fine upto 15kW for donkeys, allowing for diversity. never even hots up a 32A MCB above warm.

Click to expand...

I believe this actually includes a 5A allowance for a socket too. My diversity calculation suggests that without a socket, A 32A circuit will power up to 19kW of cooking appliances:

(32-10)=22
22/0.3=73.3
73.3+10 = 83.3
83.3 X 230 = 19159W

 

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Dustydazzler

• Oct 8, 2021

• #11

ToonSparky said:

Whats your thinking behind your first comment out of interest?

Click to expand...

Not very scientific but i have seen several vids on the web where people have passed rather large currents through small cables with no ill effect , i think John Ward did one with 1.5 and it took 70+ amps before he got it smoking

Now I am not suggesting that we should bend or ignore the manufacturers recommended current ratings but in reality a cable clipped in free air will take much more current quite happily than it is rated for

But as I say , you should install cable as per the regs and manufactures instructions

 

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• Oct 8, 2021

• #12

agree. tested one once, a 16mm T/E carrying 110A. it managed to reach 40 deg.after 20 minutes when the 63A MCB tripped. this was a pub/restaurant kitchen.

 

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• Oct 8, 2021

• #13

Rockingit said:

Even if it's 'only' 12.5kw you're into 10mm cable anyway so not sure of the dilema?

Click to expand...

Like some of the replies above 12.5kW is fine on a 6mm with diversity, whereas 15.8kW is pushing it.

I'm a bit surprised at all the suggestions of 10mm when only 12.4kW. Do you guys not apply diversity as in the OSG?

 

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• Oct 8, 2021

• #14

Just found the manufacturers instructions which says 6mm.
Im happy with that.
Thanks for all the replies ?

 

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robd

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• Oct 9, 2021

• #15

Haven't looked lately but there always used to be a bit in the on site guide on cookers..15kw 32a MCB 6mm cable.. something like that

 

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• Oct 9, 2021

• #16

HappyHippyDad said:

Just found the manufacturers instructions which says 6mm.
Im happy with that.
Thanks for all the replies ?

Click to expand...

How are manufacturers able to suggest a cable size without knowing length of the run and applicable rating factors etc?

 

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robd

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• Oct 9, 2021

• #17

ToonSparky said:

How are manufacturers able to suggest a cable size without knowing length of the run and applicable rating factors etc?

Click to expand...

Probably just talking about from the wall under the appliance I should think like when they supply a length of flex or make it pre flexed

 

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HappyHippyDad

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• Oct 9, 2021

• #18

ToonSparky said:

How are manufacturers able to suggest a cable size without knowing length of the run and applicable rating factors etc?

Click to expand...

Good point!