Wire selection for Siemens induction hob

[elliott138]

Hi Guys,

i just wanted some confirmation of the size of cable i need for my new siemens induction hob. The hobs electrical connection is 10.8KW and i've used the tlc-direct calculator and it states i need 16mm is this correct for the 47amps the hob needs?

the hob will be on it's own 50a MCB circuit.

many thanks

 

[ban-all-sheds]

1. http://www.tlc-direct.co.uk/Book/6.2.1.htm
   
   
2. What do the installation instructions say?
   
   
3. What are you doing about Building Regulations compliance - getting approval, notifying, getting a completion certificate etc?
   
   
4. What about testing?
   
   

 

[riveralt]

Follow the hob instruction guide but 10.8kw after applying diversity equates to 21Amps or so - if you have a socket at your cooker switch then add 5Amps so total 26Amps. These figures assume no derating factors apply.
32 Amp MCB (probably will need an RCD as well) 6mm T&E cable.

 

[elliott138]

1. http://www.tlc-direct.co.uk/Book/6.2.1.htm
   
   
2. What do the installation instructions say?
   
   
3. What are you doing about Building Regulations compliance - getting approval, notifying, getting a completion certificate etc?
   
   
4. What about testing?
   
   

i've looked through them and they just state that qualified installer should be used, not much help really. the main problem is that at full power the hob can demand 47amps, how ever unlikely that would be i'd rather put in 16mm now instead of finding out 10mm wasnt enough.

a family friend will be testing the circuit and making all the final connections i just want to lay the cable ready for him

 

[riveralt]

i've looked through them and they just state that qualified installer should be used, not much help really. the main problem is that at full power the hob can demand 47amps, how ever unlikely that would be i'd rather put in 16mm now instead of finding out 10mm wasnt enough.

If you feel 16mm cable is required then carry on.

a family friend will be testing the circuit and making all the final connections i just want to lay the cable ready for him

One assumes he will be contacting your Local Authority Building Control via his competent persons scheme then.

 

[TonOfSand]

If this is a domestic hob then it's very unlikely that you'll need 16mm wiring.
Bear in mind the manufacturer is giving worst case because of litigation and, as it's an induction hob, size and number of pots make a difference. Cable ratings are vastly overcompensated in my opinion. For your piece of mind go for 10mm.

 

[Taylortwocities]

Cable ratings are vastly overcompensated in my opinion.

I wonder why they go to all the trouble of producing those tables in the Wiring Regulations then?

You sound like one of those people who just bung in whatever cable they have in stock, never mind if its suitable for the job.

....oh, I wonder where that fire engine is going......

 

[ericmark]

at full power the hob can demand 47amps

Are you sure? My induction hob is so arranged that boost can only be used when the other area in the pair is not being used. So although we have 2 x 3KW and 1 x 3.7kW and 1 x 2.4kW only 6.7kW could be used and that has a time limit of around 4 minutes.

Manufacturer states with my induction hob it needs a 32A supply even though it also includes two ovens and one of them has 4 elements fitted.

Think you need to read instructions again? If it really needs 47A then I would say it's not for domestic use.

 

[EFLImpudence]

Apart from anything else; how are you going to connect 16mm² to a hob?

Some flats only have 10mm² supplying everything.

 

[TonOfSand]

I wonder why they go to all the trouble of producing those tables in the Wiring Regulations then?

Table: Nominal current-carrying capacity of general-purpose, two-core, PVC-insulated copper cables at 30 degrees celcius. Source: IEE Wiring Regulations table 4D2A
Conductor size Current rating (amps):
(mm) Enclosed in a wall Enclosed in conduit Clipped to a surface Free

1: 11 13 15 17
1.5: 14 16.5 19.5 22
2.5: 18.5 23 27 30
4: 25 30 36 40
6: 32 38 46 51
10: 43 52 63 70

I remember being surprised at the current carrying capactiy of 2.5 when studying this stuff.

there's the table, say no more...and they go to all the trouble of producing those tables again and again so they can charge you a fat fee for their literature, inspections, affiliations, membership, tuition, certificates etc. as a result of legislative government job creation policy where everyone needs a licence from the state to earn a living.

 

[EFLImpudence]

10800/230(probably 240)=46.96-10=36.96x0.3=11.09+10=21.09A (+5=26.09)

Twin & Earth - Table 4D5.

OP is entering the wrong number in TLC cable calc.

 

[ban-all-sheds]

i've looked through them and they just state that qualified installer should be used

Ah.

a family friend will be testing the circuit and making all the final connections i just want to lay the cable ready for him

That's not how it works.

//www.diynot.com/wiki/electrics:part-p

 

[ban-all-sheds]

OP is entering the wrong number in TLC cable calc.

He's not assuming any diversity:

the main problem is that at full power the hob can demand 47amps

Which is his prerogative as designer. But you'd hope that someone deciding to assume the role of electrical circuit designer would be more certain of his knowledge and competence.