I have just bought a stand alone Smeg(John Lewis) electric cooker with a ceramic hob. On the instructions it says it requires a 45A popwer supply. The current cooker is installed with a seperate circuit and 32A mcb as wll as seperate cooker swich. As The maker of my distribution unit only makes 40 or 50 MCBs. Which should I use
Connecting a smeg cooker
- Thread starter cheddardave
- Start date
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You cannot simply replace the mcb to a higher rated one, it is there to protect the cable from overload as much as the appliance. So if the cable supplying your current cooker is not big enough to carry the load of the new cooker then the cable will have to be replaced aswell as the mcb.
Your cable needs to be at least 6mm this can carry 47A, it could be possible to calculate diversity but you must follow manufacturers instructions. So if they say 45A, 45A it must be.
Why can you not get a 45A mcb what type of CU do you have?
Now for the tricky stuff, introducing a new MCB to your board will be notifiable work under part p of building regs.
//www.diynot.com/wiki/electrics:part_p
You will also need RCD protection.
Why can you not get a 45A mcb what type of CU do you have?
Now for the tricky stuff, introducing a new MCB to your board will be notifiable work under part p of building regs.
//www.diynot.com/wiki/electrics:part_p
You will also need RCD protection.
The CU is a Hagar and they dont do 45a mcb. The current cable is 6mm with a 32a mcb installed into the cu. I was going to use this existing cooker circuit with an upgraded MCB.
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How does the 6mm cable run distance and method ie does it run through any thermal insulation or grouped with any other circuit during it's run to the cooker. This could have an effect on the current the cable can carry safely.
Assuming the cable is Twin and Earth, the cable will not carry 50A as 47A is the max it can carry with no de-rating factor calculated.
As I stated changing the MCB size will be notifiable work (building controls must be informed) as this will now be deemed a new circuit and new circuits should have RCD protection.
A 40A MCB will not effect the safety of the installation, providing cable can carry this (de-rating as mentioned) but will mean your cooker will not function at it's optimum.
Out of interest, what output rating is the cooker?
Assuming the cable is Twin and Earth, the cable will not carry 50A as 47A is the max it can carry with no de-rating factor calculated.
As I stated changing the MCB size will be notifiable work (building controls must be informed) as this will now be deemed a new circuit and new circuits should have RCD protection.
A 40A MCB will not effect the safety of the installation, providing cable can carry this (de-rating as mentioned) but will mean your cooker will not function at it's optimum.
Out of interest, what output rating is the cooker?
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