Cable Capacity to Induction Hob

[self builder 123]

Hi

I have a 10.8kW induction hob supplied by a 6mm sq PVC coated 2 core cable direct from a 40A MCB, which is protected by an RCD. The cable is clipped to a timber joist with mineral wool fitted to the side of the cable along its full length.

From what I have read this cable is down rated to 32A for this installation. Is this correct ?

I also understand that the theoretical maximum current which could be drawn by the hob is 10800/230 = 47A.

By applying diversity the hob would typically be expected to draw 10A + 30% of 37A = 21A.

In your opinion was 6 mm sq the correct choice of cable as 21A is easily counducted or should 10 mm sq have been used ?

Should be 40A MCB be reduced to 32A ?

Cheers

 

[hairyben]

How often do you have all the burners on full blast?

Typically, never, which is why we use diversity.

 

[fattony]

christmas day

 

[ericmark]

On a normal hob your calculations would be correct. But with an induction hob there is normally a boost when only two areas are used. You have not given full specification but areas are also not of equal size so you could be looking at 15A for one ring and 30A for two even though total is only 47A so very likely 32A will be exceeded. As to if the time it is exceeded for will be long enough for the 32A MCB to trip is something else I would think unlikely and would expect a 32A MCB will hold without a problem but not enough experience with induction hobs to be certain so I would have used 10mm.
Eric

 

[hairyben]

christmas day

nope. evan with a full cooker, the oven, maybe 2 kw, cycles on/off via thermostat

hob, maybe 1 full blast? lets say 2 (not so likely) @ 2kW and 2 more simmering, in total you'd still be unlikely to push 7kW peak, probably sub 6kW continuous.

why people on here persist in telling people to rate their cooker circuits at it's full operating capacity I don't know.

 

[self builder 123]

The maximum loading for the hob is listed as 10.8kW.

Looking at the individual hot plates specs they are as follows :

Front Left 1.8 to 2.5kW ( with boost function )
Back Left 1.8 to 2.5kW ( with boost function )
Centre 1.8 to 4.4kW ( with boost function )
Front Right 2.2 to 3.3kW ( with boost function )
Back Right 1.4 to 1.8kW ( with boost function )

When the boost function is used then another hot plate must be off e.g. if you want to boost the front left then the bacl left must be off.

So if you do not use the boost functions I calculate the total load as being 9kW when all the 5 rings are on maximum.

Is a 9kW draw a lot of power for a hob ?

Is it fair to say that you would never have all 5 rings on at the maximum setting ( you may have guessed that I am not a cook !!!! ) even on Xmas Day.


At 230V the hob could safely draw ( 230 x 32 ) 7360W - based on Installation Method 15 in Table 4D5A the 6 sq.mm cable can provide 32A.

So each of the 5 hot plates could draw approximately 80% of their maximum power ?

Your feedback would be much appreciated.

 

[hairyben]

The maximum loading for the hob is listed as 10.8kW.

Looking at the individual hot plates specs they are as follows :

Front Left 1.8 to 2.5kW ( with boost function )
Back Left 1.8 to 2.5kW ( with boost function )
Centre 1.8 to 4.4kW ( with boost function )
Front Right 2.2 to 3.3kW ( with boost function )
Back Right 1.4 to 1.8kW ( with boost function )

When the boost function is used then another hot plate must be off e.g. if you want to boost the front left then the bacl left must be off.

So if you do not use the boost functions I calculate the total load as being 9kW when all the 5 rings are on maximum.

Is a 9kW draw a lot of power for a hob ?

Is it fair to say that you would never have all 5 rings on at the maximum setting ( you may have guessed that I am not a cook !!!! ) even on Xmas Day.


At 230V the hob could safely draw ( 230 x 32 ) 7360W - based on Installation Method 15 in Table 4D5A the 6 sq.mm cable can provide 32A.

So each of the 5 hot plates could draw approximately 80% of their maximum power ?

Your feedback would be much appreciated.

It's adequate. Given it's a 5 ring hob a 10mm/50A circuit would be ideal, but in reality it's never gonna trip.