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  • Any sparkies about?
  • granny_ring
    Full Member

    Getting the kitchen done soon. At the mo we have a free standing gas hob and elec double oven which has a 6mm cable feed.

    Can I run an induction hob and oven from a 6mm cable?
    Fitting a 10mm cable is going to be too much hassle so if it’s not possible then will replace like for like.

    Thanks.

    rwamartin
    Free Member

    What are the ratings of the hob and oven? These are required to calculate the load.

    Rich

    andyg1966
    Full Member

    Whats the existing current rating of the breaker. We have just done exactly the same. Our breaker was already 45A (assumed cable was appropriately rated). New Richmond 1100ei cooker has a required fuse of 32A.

    Works fine for the last year.

    granny_ring
    Full Member

    I’m no good with understanding electrics 🙂
    Fuse is 32A. How do I work out the load and ratings ie what’s the safe max for the 6mm cable?
    Thanks again.

    andyg1966
    Full Member

    What is the current rating of the cooker circuit breaker in your consumer unit?

    That will tell you if your existing cable is OK. If your breaker is 45A, your cable will be at least 45A and your new cooker will say in the specs. If less than the rating of the existing breaker you are OK.

    rwamartin
    Free Member

    6mm installed in a wall is rated at 47A.

    As Aandyg1966 implies, the mcb must be less than the current rating of the cable whilst the load has to be less than or equal to the current rating of the MCB. In essence the cable must be able to carry the load and the mcb break before the cable acts as a fuse and burns.

    To complicate matters you can apply “diversity” to the load as the oven will not be pulling full whack all the time.

    The problem you have is the hob is only going to have a small cable to it as it only requires a small current to fire the gas ignitor. As a consequence the cable to the hob will be undersized (probably only 1.5mm at most) for the mcb you’ll be fitting for the oven.

    Now, the regs allow this if the cable is less than 3m, the load is fixed (ie can’t vary) and the cable size is such that the prospective fault current (PFC) can be carried until the MCB clears the fault.

    Optimally you’d need to check the PFC, work out the mimimum cross sectional area of the cable from the adiabatic equation and see if it is big enough.

    Alternatively feed the hob from the kitchen ring fused down via a fused spur to 3A.

    Rich.

    Blazin-saddles
    Free Member

    You can get an induction hob that will run from 13a these days, so you could have the ring extended to provide power for one of those

    or

    you could run a single oven instead of a double and use the 6mm supply for the induction hob and extend the ring for a single oven (normally 13a these days)

    Your 6mm cable won’t have enough capacity for a double oven AND an induction hob, however you do the math.

    granny_ring
    Full Member

    Thanks guys, I’ll try and find a hob or oven that will run off a 13A spur, consult with the boss and decide which.
    Failing that I’ll revert to default 🙂
    Cheers.

    russ295
    Free Member

    I’d say probably. I’ve fitted quite a few and never had any problems.
    As Rich says “diversity” can be applied which will in theory reduce the demand. Have a look at the link.
    https://www.tlc-direct.co.uk/Book/6.5.2.htm
    The 13a ones don’t have the ohmph that a proper one has!
    You really need to find the rating in kilowatts of both appliances to determine the maximum demand.

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