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  1. Soulsurfer
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    Soulsurfer Electrician's Arms

    Location:
    Channel Islands
    Hi all,
    Just looking into a kitchen refit where the customer has gone a bit excitable with the cooking side of things !

    Have done lots of installs with two appliances on the one circuit but anyone know of any issue with feeding three rather than run a new circuit for say the new hob alone ?

    I have an existing 32A rcbo on a 6mm twin for built in oven now and hob but new kit is an oven at 3.45kW
    Combi oven / micro at 3.6kW

    and finally an induction hob at 5.6kW
    24.3A fuse rating on spec sheet so they haven't allowed any diversity.
    Anyone fitted them with a diversity applied ? as I haven't fitted any induction before.

    I'm making it a shade under 27A for the oven and combi together,

    and if allowed on induction 18.7A approximately but I'm thinking likely run a new circuit from cu at the full load rating the manufacturer of the hob has given.
     
  2. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Looking at OSG Appendix A and noting coffee not kicked in yet so hopefully I've understood correctly ...
    10+13.5+5(say)=28.5A for domestic and
    24.3+12.5+9=45.8A for small shop.
    Translation : if the customer likely to go nuts with new kit (ask them?) try to sell them on the idea of a new supply :)
     
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  3. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    When I've calculated diversity for domestic ovens, I've applied diversity to each appliance individually, not the total load added together.

    I'm not sure if that is the right interpretation, but my thinking is the end user can operate each appliance as they choose to, as opposed a singular appliance preventing them from using all heating elements, if you get my drift. Like a single oven, where you can't use the grill & main oven simultaneously.
     
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  4. Richard Burns
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    Richard Burns Trusted Advisor

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    Cambridgeshire
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    Richard Burns
    It would probably be OK on the standard arrangement (subject to Wilko's caveats) but if you have the option to run a new supply for the hob then this means you are very safely covered.
    The customer will need to be informed that they are using a lot of power and be sensible!
    If you turn everything on and then jump in your 10.5kW electric shower you could get the main 60A fuse to go!
     
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  5. Murdoch
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    Murdoch Electrician's Arms

    Location:
    Woking
    2 appliances - OK, adding a 3rd may push it............ I would probably recommend a 2nd supply OR changing the induction hob for one with a 13A plug!
     
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  6. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
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    Wilko Electrics
    It would be interesting to compare the two methods, hopefully it would have the same outcome :)
     
  7. buzzlightyear
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    buzzlightyear Electrician's Arms

    Location:
    star command
    looking at that loading you have given .I makes more sense.reg 433.1.103 (111)connecting cookers hobs
    exceeding 2kw on own dedicated r/circuit.
    how many times we have been around the houses with hobs &cookers on this forum!
     
  8. buzzlightyear
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    buzzlightyear Electrician's Arms

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    star command
    I forgot soulsurfer in channel islands .by the time the bong drums start banging. he would be able to hear it!
     
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  9. hightower
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    hightower Electrician's Arms

    Location:
    Durham
    My understanding is, using a dedicated radial circuit means not connecting it among other appliances such as on the RFC etc. It doesn't mean a radial for each appliance over 2kW.

    You can have a dedicated radial for all three appliances, just so long as that circuit meets design requirements. It's still a dedicated circuit for those appliances.
     
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  10. buzzlightyear
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    buzzlightyear Electrician's Arms

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    star command
    when I do installs cookers hobs ,on the own dedicated circuit. but that's for me only.
    with this day and age you will never know .
     
  11. Phil Thompson
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    Phil Thompson Let us light up your life! Electrician's Arms

    Location:
    Newtownards
    Business Name:
    Brite Spark Electrical
    After being caught out a few times by being given incorrect (smaller) kw ratings of induction hobs, I now just pull in a seperate feed for them than the oven when I hear induction hob mentioned.

    Last time was given a similar rating to the OP, however on day of fitting it was actually 7.8Kw.

    I see more and more folks on my Facebook feed doing batch cooking at weekends due to work commitments during the week. So they are using all rings and ovens to be doing as much as they are doing, no longer just a Christmas dinner thing anymore for some households to be using full ratings of cooking appliances as it used to be.
     
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  12. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    Don't think your following what I'm suggesting Wiko.

    For the three appliances of 3450w, 3600w & 5600w, using Table A1 (applying diversity separately) I get a figure of 37.5amps (no sockets).

    Or have I got my maths wrong?
     
  13. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

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    all 3 in use are never going to pull >45A, so a single 45A isolator, fed 6mm on a 40A breaker if method C. 10mm cable id insulation correction required.
     
  14. Soulsurfer
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    Soulsurfer Electrician's Arms

    Location:
    Channel Islands
    What's the bong drums dare I ask !
     
  15. buzzlightyear
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    buzzlightyear Electrician's Arms

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    star command
    [​IMG] their you go soul train!
     
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    Last edited: Aug 10, 2017
  16. Midwest
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    Midwest Electrician's Arms

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    Oxfordshire
    buzz are you sparksburntout's twin or doppelganger or even his alter ego, as he never seems to bring you to task about your atrocious spelling and grammar o_O
     
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  17. Soulsurfer
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    Soulsurfer Electrician's Arms

    Location:
    Channel Islands
    Ha ha loads of them today ! Battle of Flowers on. Bongo bongo time lol, only the other Bong thing you'll find down where I surf but that's nothing to do with electrics :grimacing:
     
  18. Soulsurfer
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    Soulsurfer Electrician's Arms

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    Channel Islands
    Ha ha loads of them today ! Battle of Flowers on. Bongo bongo time lol, only the other Bong thing you'll find down where I surf but that's nothing to do with electrics :grimacing:
     
  19. buzzlightyear
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    buzzlightyear Electrician's Arms

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    star command
    upload_2017-8-10_17-2-25.png sorry sir !
     
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  20. Wilko
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    Wilko Electrician's Arms

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    Berkshire
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    Wilko Electrics
    You're right, but I've got it now. Your maths are correct, or I make the same mistake :)
    The answer is quite different using Table A1 method, as its got 3 lots of 10A, vs only one lot when using Table A2. I think A2 is the one to use for this, just going by its name (?).
     
  21. Soulsurfer
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    Soulsurfer Electrician's Arms

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    Channel Islands
    So table A2 by using the total loads, I'm getting 41.5 A after diversity ?
     
  22. Dave OCD
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    Dave OCD Electrician's Arms

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    Cornwall
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    Hendry Electrical Services
    Hmmm you could be on to something here, another little known fact is that Tel and Pete are actually twins. :D
     
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  23. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

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    not treue. pete is 4 months older than me. that,s 18 weeks to correct the minor defects and create perfection.
     
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  24. Midwest
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    Midwest Electrician's Arms

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    Oxfordshire
    According to the introduction on Appendix A, Table A1 is used to calculate the current demand for a final circuit, making an allowance for diversity. Table A2 is used for calculating the current demand of an installation consisting of a number of final circuits, also making an allowance for diversity.

    The 'definition' used in both (for cooking appliances) is the same (IMO), although they are written differently.

    Appendix H, and H4 advises the use of Table A1 for cooker circuits in household premises. It states that a 30 or 32 A circuit is usually appropriate for household or similar cookers of a rating up to 15kW. It also advises about the connection of two or more appliances on one circuit.

    Mind you, these diversity tables were composed 'hundreds' of years ago, before induction hobs, steam ovens etc were introduced. Down to the designer. :)
     
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  25. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

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    steam ovens? are we now regressing back to the age of steam, when things were designed and engineered to perform, regardless of accountants going for cheapest option,, broken within weeks instead of decades?
     
  26. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    No not steam engines, steam ovens bit like this;

    Hot tub.png
     
  27. Rpa07
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    Rpa07 2000 posts - only 46379 behind Telectrix! Electrician's Arms

    Location:
    Bristol
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    Ebenezer electrical
    18 week wonder well that's another whole topic on the forum - out with the old 5WW in with the new!
     
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  28. Wilko
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    Wilko Electrician's Arms

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    Berkshire
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    Wilko Electrics
    Re reading the docs, I see what you mean and I'm seeing the wisdom. Table A1 title has "points of utilisation or current using equipment" and in this case there are 3 of them, so apply it 3 times :)

    Learning everyday, cheers !
     
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  29. Soulsurfer
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    Soulsurfer Electrician's Arms

    Location:
    Channel Islands
    So in your opinion Wilko would you go by 3 different applications of the 10A +30% calc and cover all (15kW) on one 50A control switch or seperate radial say for one appliance and seperate isolator of course ?
     
  30. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    I think if you have one existing 32A radial, I'd be inclined to drag in another. If you have a butchers at H4 OSG (described by some, as a storybook with pictures), it makes reference to isolation, and refers to reg 536.2, which I can't make sense of, but think says refer to manufacturer?
     
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  31. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
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    Wilko Electrics
    Isn't the problem that you've only got 6mm and a 32A mcb? Now I've smelt the cooking I def would not add this new hob to that circuit, a change from what I implied at 6:30 this morning ...(darn, too late to edit?). If circuit was at least 40A then it's a maybe but we are back to actual useage vs OSG advice. A 2nd 6mm and it can be Christmas every day :)
     
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  32. Soulsurfer
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    Soulsurfer Electrician's Arms

    Location:
    Channel Islands
    Yes mate, I did read that and the reg which is another quite flouncy sentence :D and in my mind is taken as add an isolation switch to switch the appliances conveniently rather than one switch to shut off 3 different appliances for instance. Either way thanks for input from all ;) I'm nearly off to the airport as Mallorca soon !
     
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  33. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    Lucky ****
     
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  34. Rpa07
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    Rpa07 2000 posts - only 46379 behind Telectrix! Electrician's Arms

    Location:
    Bristol
    Business Name:
    Ebenezer electrical
    At least take the OSG with you for lying by the pool reading material - you'll be clued up by the time you return!
    Happy holiday!
     
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  35. Soulsurfer
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    Soulsurfer Electrician's Arms

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    Channel Islands
    Got to get through Gatwick & out to Stansted & away first !
    It's all a struggle really :rolleyes:
    Enjoy your summer chaps ;)
     
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  36. Soulsurfer
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    Soulsurfer Electrician's Arms

    Location:
    Channel Islands
    Just need a postcard wall here now
     
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