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Manufacterer's advice/instructions

whjohnson
Been asked to connect up a used rangemaster all-electric cooker. No rating plate but model name is 'classic 90'. It has an induction hob.

Existing cable is 6.00mm on a 32A mcb.

Phoned the manufacturer who said it would be fine, since diversity could be applied but we would have to fit a cooker switch without a built in 13a socket and uprate the mcb to 40A.

I am a little troubled to say the least.

Comments welcome.
  • 0

    Alasdair Anderson:




    John Peckham:

    `You cannot apply diversity to a single piece of equipment for sizing circuit protection and cable sizing. Diversity can be applied to individual items of equipment when considering the maximum load on a distribution circuit or an installation.


    The cable and the circuit protection should be rated for the "Plated" load or the manufacturers instructions.




    This gives rise to a bit of an anomaly....

    If I have a cooker with a 7.5kW four plate hob and a 3kW double oven/grill I can't apply diversity.

    If I have a fitted kitchen with a built-in 3kW double oven/grill and a separate 7.5kW four plate hob then I can apply diversity.

    They surely can't both be right.



    They can be if the manufacturer has applied diversity when it specifies the size of the supply.

  • 0

    John Peckham:

    `You cannot apply diversity to a single piece of equipment for sizing circuit protection and cable sizing. Diversity can be applied to individual items of equipment when considering the maximum load on a distribution circuit or an installation.


    The cable and the circuit protection should be rated for the "Plated" load or the manufacturers instructions.




    This gives rise to a bit of an anomaly....

    If I have a cooker with a 7.5kW four plate hob and a 3kW double oven/grill I can't apply diversity.

    If I have a fitted kitchen with a built-in 3kW double oven/grill and a separate 7.5kW four plate hob then I can apply diversity.

    They surely can't both be right.

    Alasdair

  • 0

    AJJewsbury:




    You cannot apply diversity to a single piece of equipment for sizing circuit protection and cable sizing. Diversity can be applied to individual items of equipment when considering the maximum load on a distribution circuit or an installation.



    Where on earth did you dig up that quote from? AFAIK that kind of thinking was dropped from the regulations decades ago - about the time we started using 13A sockets - and cooker diversity was well established even before that.


    Isn't this a bit like rating a double 13 A socket at 13 A? The rating is what it says it is.


    So I just looked up a range cooker on John Lewis's web site which specifies (for a particular model) a 45 A fuse. Note, fuse not MCB! This is for 7.4 kW @ 230 V, which by my maths is 32 A.


    However, the technical specs specify a maximum power of 14.8 kW, so clearly the manufacturer has applied some diversity.


    Oh yes, and don't install it in your bathroom. No, seriously! "The cooker may be installed in a kitchen/kitchen diner but NOT in a room containing a bath or shower." ?

  • 0

    You cannot apply diversity to a single piece of equipment for sizing circuit protection and cable sizing. Diversity can be applied to individual items of equipment when considering the maximum load on a distribution circuit or an installation.



    Where on earth did you dig up that quote from? AFAIK that kind of thinking was dropped from the regulations decades ago - about the time we started using 13A sockets - and cooker diversity was well established even before that.

      - Andy.

  • Former Community Member
    0 Former Community Member
    And "the short of it" - isn't that a fault?


    No such thing as an electrical fault....................


    All mechanical or chemical failures!!!!!!


    Regards


    BOD
  • 0

    perspicacious:
    Who said anything about fault conditions?


    Ah, I was quoting out of the 17th: 433.1 "Every circuit shall be designed so that a small overload of long duration is unlikely to occur." and earlier editions echo the same.


    My 18th isn't to hand so apologies if I've got the wrong Reg no.




    Still there in the 18th. But surely, the all-singing-all-dancing range cooker only ever draws its full whack for a short duration (a few minutes) before pans start to boil and the rings are turned down? I distinctly remember this being discussed during my training course. Diversity is an odd thing if you have never heard of it.


    And "the short of it" - isn't that a fault? ?

  • Former Community Member
    0 Former Community Member
    Who said anything about fault conditions?


    Ah, I was quoting out of the 17th: 433.1 "Every circuit shall be designed so that a small overload of long duration is unlikely to occur." and earlier editions echo the same.


    My 18th isn't to hand so apologies if I've got the wrong Reg no.


    Regards


    BOD


  • 0

    perspicacious:

    And conversely, when I was doing a lot of pub PIRs (as they were at the time), it was quite usual to find an innocent looking twin basket deep fat fryer with two 13 A plugs prefitted when it was actually one appliance. The landlord saw nothing wrong with plugging it into the nearest double socket with the consequence of there being less than 3 kW left on the rfc in a very busy kitchen........




    Let alone overloading the twin socket!

  • Former Community Member
    0 Former Community Member
    I fear that the problem is that one-upmanship encourages the manufacturers to declare the maximum possible power. However, it is perfectly reasonable for them to specify a smaller cable in the small print than may otherwise be expected.


    And conversely, when I was doing a lot of pub PIRs (as they were at the time), it was quite usual to find an innocent looking twin basket deep fat fryer with two 13 A plugs prefitted when it was actually one appliance. The landlord saw nothing wrong with plugging it into the nearest double socket with the consequence of there being less than 3 kW left on the rfc in a very busy kitchen........


    Regards


    BOD
  • 0

    perspicacious:

    Is that the long and short of it Chris?


    How long is the turkey in the oven for?!!!!!


    Regards


    BOD


    PS check your PM.........!




    Who said anything about fault conditions?


    Don't know. I have never cooked one.


    Back to the OP: what is the CSA of the cooker cable? That must give some indication as to the appropriate size of the fixed wiring.

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