Cooker Instal

[Caledonia]

Another boring cooker question. I have to instal a new freestanding double oven cooker, total power consumption 11.5 Kw. The manufacturer recommend cable rating 6mm. They offer no advice on MCB rating but the existing one is 45A. There is an isolation switch adjacent to the cooker the value of which I cannot establish but which I assume is 45A.
Does this seem O.K and is the manufacturers cable recommendation based on the 10A + 30% of remaining load formula?

 

[Big_Spark]

Another boring cooker question. I have to instal a new freestanding double oven cooker, total power consumption 11.5 Kw. The manufacturer recommend cable rating 6mm. They offer no advice on MCB rating but the existing one is 45A. There is an isolation switch adjacent to the cooker the value of which I cannot establish but which I assume is 45A.
Does this seem O.K and is the manufacturers cable recommendation based on the 10A + 30% of remaining load formula?

Firstly it is likely the switch is 45A rated, and the existing MCB being 45A is acceptable in this case IF you upgrade the cable to 10mm2.

Given the potential full load potential of the cooker being 50A (11500/230V = 50A), I think you should look carefully how you will use the cooker.

Are you likely to use all four hotplates at once? If so add all their respective ratings together to calculate their probable full load potential. Then you should assess if you will be using the oven at the same time and add this potential load to the figure you already have.

Many people advocate using diversity on cookers, I don't, but on a coker of this potential load 6mm2 cable will be too small in my opinion and should be uprated to 10mm2 for safety's sake if nothing else.

The IEE recommend that you assume an 80% load potential for cookers, that is 40A, 6mm2 will not handle this load and comply with BS7671.

 

[Caledonia]

Thankyou FWL_Engineer for your prompt reply. I had my doubts but could not understand why the manufacturer had recommended 6mm. It is very unlikely that ovens and all hobs would be in use but there are a few occasions when this might occur . I know that the trip rating of an MCB is more complex than just tripping on immediate overload but would the 6mm cable be offered protection if the MCB was reduced from 45A to 30A

 

[Big_Spark]

Thankyou FWL_Engineer for your prompt reply. I had my doubts but could not understand why the manufacturer had recommended 6mm. It is very unlikely that ovens and all hobs would be in use but there are a few occasions when this might occur . I know that the trip rating of an MCB is more complex than just tripping on immediate overload but would the 6mm cable be offered protection if the MCB was reduced from 45A to 30A

Yes, if you reduced the MCB size to 32A then you would be OK.

 

[Caledonia]

Thanks again for replying so quickly. I suppose the ideal solution would be to upgrade but human nature is such that----------. Just for information my father was a plumber, of the old school, when to plumb meant, I believe from Greek, "the working of lead"and plastic piping was unknown.

 

[ban-all-sheds]

Latin - the word for lead was plumbum, which is where we get words like plumber, plumb-line, plumbing the depths, and the chemical symbol for lead; Pb.

But don't worry - the Simplified Spelling Society want to do away with all that nonsense, and utterly destroy any links to Latin, Greek, Norse etc.

 

[Caledonia]

Thank you for the correct derivation of plumber ban-all-sheds. That will teach me to do things properly and check my facts.

 

[ban-all-sheds]

Hope you don't think it was a yah-boo-you're-wrong post - just thought some people might find it interesting.

Man cannot live by BS7671 alone.

 

[Big_Spark]

Man cannot live by BS7671 alone.

You'll burn in hell for that one if you mention it anywhere near the IEE!!

 

[Caledonia]

No, Ban-all-sheds I was very happy to receive the information. It will teach me not to post when the wine bottle is at my elbow. Anyway how could a Saintly scientist have any bad intentions.
Thanks again to you and the engineer for the help given.