Wiring for Smeg range cooker

[serengetisnow]

Morning,

We would like to fit a 100cm Smeg range cooker. We have an existing range with a gas hob and electric oven. It has a 6mm2 cable. Looking at the 3rd smeg suggested wiring scenario below would it be possible to use the existing 6mm cable plus other 6mm cables from neighbouring sockets? We are just looking at options as it is a long way to run a new 10mm wire and may involve considerable replastering....

Many thanks for your help! Jane



Morning

 

[bernardgreen]

would it be possible to use the existing 6mm cable plus other 6mm cables from neighbouring sockets

It is possible but to do that would be both dangerous and non compliant.

 

[RandomGrinch]

Hi,

I'm not an electrician, but your post leaves me with a couple of questions!

What model is the range cooker?
Is it one with an induction hob?
If your existing wiring is 6mm, what value MCB do you have in your Consumer Unit?

Looking at the 3rd smeg suggested wiring scenario

I believe that relates to a 2 phase supply, and the first wiring suggestion is probably correct in your case.

 

[EFLImpudence]

the first wiring suggestion is probably correct in your case.

There is no doubt about it.

 

[serengetisnow]

OK, thanks all. The MCB associated with the current range is 32W and it is 6mm. It is a Smeg Victoria range 100cm which does have an induction hob.

 

[EFLImpudence]

Then, it will be alright on the existing circuit and 6mm² cable if <15kW (possibly up to 19kW).

An induction hob doesn't really make any difference.

 

[RandomGrinch]

An induction hob doesn't really make any difference.

I was trying to narrow down the model - if it's the Victoria TR103IBL, that's rated at 20kW, which may be a bit tight on diversity?
...and nuisance trips?

 

[EFLImpudence]

Yes, 20kW would be too much but nothing to do with it being an induction hob or an ordinary hob.

 

[bernardgreen]

Then, it will be alright on the existing circuit and 6mm² cable if <15kW (possibly up to 19kW).

A glance at a cable calculator suggests that 6 mm² is less than adequate for 10 kW

 

[serengetisnow]

I was trying to narrow down the model - if it's the Victoria TR103IBL, that's rated at 20kW, which may be a bit tight on diversity?
...and nuisance trips?

Apologies- it is a TR013IP/G

 

[EFLImpudence]

A glance at a cable calculator suggests that 6 mm² is less than adequate for 10 kW

Its a cooker and why have you chosen those parameters?

If the existing circuit is compliant, then what I wrote is correct.

 

[RandomGrinch]

A glance at a cable calculator suggests that 6 mm² is less than adequate for 10 kW

But still protected by the 32A MCB

Its a cooker and why have you chosen those parameters?

It is nominally rated at 20kW, but has 3 ovens and 5 zones on the hob.

All in my non-expert opinion and I'm happy to be corrected!:

As above, if the circuit is compliant, it will be 'safe' to connect the range to your existing wiring.
However, it will not be correct; especially if you are a MasterChef who uses all the ovens and the hob at the same time!
Running any circuit at its limit, for an extended length of time is a bad idea.
You might run into nuisance trip issues, and if a trip causes damage to the cooker, your warranty may be affected, as the installation doesn't conform with the MI.

 

[JohnW2]

A glance at a cable calculator suggests that 6 mm² is less than adequate for 10 kW

Why 10 kW? Even a 19kW cooker is only about 7 kW with diversity.

Kind Regards, John

 

[bernardgreen]

Why 10 kW? Even a 19kW cooker is only about 7 kW with diversity.

That calculator could not find a suitable PVC twin and earth cable for a load greater than 10kW

Above 10kW it was suggesting SWA

As for diversity, It can be applied to most multi-element appliances in average use but unless the appliance has integral power management a rating based on diversity alone cannot be relied on.

If a 19kW cooker will in reality and due to diversity only be a maximum load of 7kW then why does the manufacturer describe it as a 19kW appliance.

My dual ring induction hob does have integral power management which prevents both rings being set to full power at the same time.

 

[JohnW2]

That calculator could not find a suitable PVC twin and earth cable for a load greater than 10kW

As I said, the 'after diversity' consumption of even a 19 kW cooking appliance is a lot less than 10 kW.

As for diversity, It can be applied to most multi-element appliances in average use but unless the appliance has integral power management a rating based on diversity alone cannot be relied on.

For decades it has been accepted that, in practice, the standard allowance for diversity works satisfactorily even without 'integral power management'. You're free to have a different view, but I think it is wrong to give the impression that yours is a widely-held or widely-accepted view.

If a 19kW cooker will in reality and due to diversity will only be a 7kW load then why does the manufacturer describe it as a 19kW appliance.

You know the answer to that as well as I do. The "19 kW" is the theoretical maximum that it would draw (for a very short period of time) if every part of it was turned on from cold simultaneously.

Don't forget that, underlying and underpinning the concept of diversity is the fact that a cable with a rated CCC of, say, 32A (i.e. 7.36 kW at 230V) is considered to be capable of carrying about 46 A (nearly 11 kW) continuously for an hour without coming to harm - so could carry a lot more than that without coming to harm for the much shorter periods for which any cooker will draw its 'maximum rates load' (e.g. "19 kW").

My dual ring induction hob does have integral power management which prevents both rings being set to full power at the same time.

One most often sees that sort of power management in hobs designed to be run from a 13A supply (i.e. a plug/socket). Otherwise, as above, it is usually unnecessary.

Kind Regards, John