Why is a cooker circuit generally 6mm and 32a

[joehat]

As above why is this as I have had a thought and a 20a 2.5 mm cable would be sufficient?
Even in my new built it has an oven and hob both 32a radials for each on 6mm cable? Each with a 13a plug on the appliance as diversity shows around 10a max.
so even with an upgraded appliance I don't see more than 15a a max. ?


Regards Joe

 

[Darkwood]

Diversity is often used to give a average demand of an installation, when you are weighing up for a final circuit you must be cautious when applying diversity to the circuit as there will be times when say the oven is at full power for a long duration like when its heating the oven up and maybe you have just put the grill on too (on models where this is applicable of course).

I normally wouldn't recommend diversity be applied to a standard electric oven but when you get these big monster ovens sat in a domestic house (not for commercial use) then you can reasonably apply a diversity factor IMHO..

If the oven or hob come with a 13amp plug on then cable calcs allowing their is no reason you cannot run a 20amp circuit, 6mm gives a future proof in case you change the oven or hob.

 

[Andy78]

Your new build house will have been built to a specification. It will also have been built with no idea of the type of cooking appliances the end user will install, so the worst case scenario has been catered for.
I have seen both hobs and ovens that require a 32A supply according to manufacturer's instructions.

I tend to install 4mm 32A circuits if the installation method will allow, which is the majority of the time. I have also installed 20A and 25A cooker circuits.
The use of 6mm cable for a 32A radial could be down to derating factors along the cable run or just a hang over from the traditional use of 6mm for a cooker radial. I believe this is down to when 6mm, or imperial equivalent, was protected by a 30A fuse and was not allowed to be any smaller (see appx 4 factor cf ) It just never changed in the general conciousness with 32A MCBs that you could get away with a smaller cable in some situations.

 

[ruston]

Mainly carried on because electricians carried 6mm when 4mm was less in demand. Showers were getting fitted with 6mm, the added expense of buying 4mm for cookers didn't add up

 

[HandySparks]

...Even in my new built it has an oven and hob both 32a radials for each on 6mm cable? Each with a 13a plug on the appliance as diversity shows around 10a max..

What sort of hob is this that can run on a 13A plug?

 

[Andy78]

What sort of hob is this that can run on a 13A plug?

I've seen a couple of induction hobs that come fitted with a plug top. I was amazed too !

 

[123]

What sort of hob is this that can run on a 13A plug?

A gas one :bucktooth:

 

[yellowvanman]

I think the use of 6mm for 32A cooker circuits is historical.

In the days of BS3036 re-wireable fuses, only 6mm met the extra current carrying requirements associated with those fuses. The relevant reg nowadays is 433.1.101 (only got green book indoors, so maybe slightly different number in BYB)

 

[7029 dave]

As above why is this as I have had a thought and a 20a 2.5 mm cable would be sufficient?
Even in my new built it has an oven and hob both 32a radials for each on 6mm cable? Each with a 13a plug on the appliance as diversity shows around 10a max.
so even with an upgraded appliance I don't see more than 15a a max. ?


Regards Joe

That is standard radial for cooker circuit, has been for decades, which is good enough for me.

 

[Marvo]

I don't think a 6mm 32A circuit is a bad idea considering some of the oven or even double oven and hob arrangements that are all the rage in houses nowadays.

 

[telectrix]

as all the above have said. also, fwiw, you may have a 32A RFC for your upstairs sockets, yet add up all the things you are likely to plug in in bedrooms, and the demand will be <5A.

 

[Guest77]

As above why is this as I have had a thought and a 20a 2.5 mm cable would be sufficient?
Even in my new built it has an oven and hob both 32a radials for each on 6mm cable? Each with a 13a plug on the appliance as diversity shows around 10a max.
so even with an upgraded appliance I don't see more than 15a a max. ?


Regards Joe

How do you know what size oven will be installed? the person moving into a new house may want a 20kw range, even with diversity it is still a large unit.

 

[plantpot]

Is this thread in connection with the "cooker cable" in general discussion thread via the back door so to speak.