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Induction Hob again

Former Community Member
Former Community Member
I hope that you don’t find me impudent but I am having difficulty finding an electrician to explain why they will not install the induction hob and double oven that we are looking to fit in our new kitchen.
We have chosen a hob 7.4 kW and oven 6.3 kW. The cooker radial circuit has 6mm2 cable with 40A MCB. The run is some 12 m. The house was built (converted) in 2002 and inspected last year (DPN18C). We cannot run an extra cable because the CU is separated from the kitchen without a horizontal floor or roof space and presumably runs the existing cable through the stud walls.
The kitchen fitting company electrician has visited but won’t carry out the work unless we sign an indemnity as it would invalidate our insurance and the appliance guarantee. He suggested instead two plug-in ovens which we could add to the ring main. I have contacted four other local electricians but they all use 13.7 kW means 59.7 A which means 10 mm cable and ignore my request to consider diversity.
Should I give up and accept the two oven solution or perhaps a gas oven?
Do you know of a way of finding someone who understands diversity?
Am I simply wrong?

Parents
  • Playing a bit of Devil's advocate, if you rely upon diversity, why do you need such powerful appliances?


    To my mind, one hob + one oven = one cooker.


    Paragraph 311 of BS 7671 permits diversity to be taken into consideration. Table A1 of the On-Site Guide allows 10 A of the rated current + 30% of the reminder = 10 + 15 = 25 A.


    If the cable runs in an insulated stud wall (insulation may be there for sound attenuation) the current carrying capacity of 6 mm² T&E is 35 A provided that the cable is in contact with the inner wall surface.


    One of the problems here is that a large proportion (the majority?) of the population have no idea about cookery. The big range on Christmas Day is the usual example. In engineering terms, if you turned everything on at the same time, it would briefly pull the full rated current, but as the thermostats click in and out, diversity comes into play. In culinary terms, you do not cook your vegetables when the turkey (yuk!) goes in, and you do not put your peas on at the same time as your potatoes.


    Don't even think of putting ovens on the ring.


    IMHO, there is no problem with the installation as described.




Reply
  • Playing a bit of Devil's advocate, if you rely upon diversity, why do you need such powerful appliances?


    To my mind, one hob + one oven = one cooker.


    Paragraph 311 of BS 7671 permits diversity to be taken into consideration. Table A1 of the On-Site Guide allows 10 A of the rated current + 30% of the reminder = 10 + 15 = 25 A.


    If the cable runs in an insulated stud wall (insulation may be there for sound attenuation) the current carrying capacity of 6 mm² T&E is 35 A provided that the cable is in contact with the inner wall surface.


    One of the problems here is that a large proportion (the majority?) of the population have no idea about cookery. The big range on Christmas Day is the usual example. In engineering terms, if you turned everything on at the same time, it would briefly pull the full rated current, but as the thermostats click in and out, diversity comes into play. In culinary terms, you do not cook your vegetables when the turkey (yuk!) goes in, and you do not put your peas on at the same time as your potatoes.


    Don't even think of putting ovens on the ring.


    IMHO, there is no problem with the installation as described.




Children
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