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Please review my MCB calculation for 16amp 3.5kw oven

Discussion in 'Electrics UK' started by pbryd, 7 Oct 2019.

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  1. pbryd

    pbryd

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    Hello guys.

    To accomodate a new 16amp / 3.5Kw oven, I have laid a 6mm T/E from my consumer unit to a new 45amp cooker switch, going onto a CCU.

    There is a spare 16A MCB in the consumer unit but my calculations tell me I need a higher rated (19) MCB.

    I = 3500 / (230*0.8) = 19.02

    Can some confirm this is indeed the right way to calculate the rating for the MCB?


    Notes
    Only the oven connects to the CCU, no other appliances
    I will be using a gas hob
    I have connected the oven to the CCU with 2.5mm T/E heat resistant
     
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  3. EFLImpudence

    EFLImpudence

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    3.5kW @ 240V (3500/240) = 14.58 Amps. That's it.

    If the 0.8 is a correction factor for some other reason, this is not necessary for calculating the current, and the cable will still be alright as 2.5mm has a maximum rating of 27A; 27 x 0.8 = 21.6A.
     
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  4. JohnW2

    JohnW2

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    Where did that "0.8" come from?

    You'll very probably find that the "3.5kW" is quoted at 240V (to make it sound more powerful?!) - which would mean a current of 14.58A (3500/240), which would reduce to about 13.98A [14.58 x [230/240)] at 230V - all well under 16A.

    Kind Regards, John
     
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  5. pbryd

    pbryd

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    You guys are very helpful.

    The 0.8 came from some calculations on an Youtube video I just watched.

    I knew I'd be better asking here, thanks.

    So just to spell it out, my 16A MCB is fine in this scenario.
     
  6. EFLImpudence

    EFLImpudence

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    Yes.

    You could change it for the usual 32A MCB if you ever buy a large cooker or larger oven and hob.
     
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  7. pbryd

    pbryd

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    Thanks. It's already too big for my kitchen, but I got it cheap, so adding the cable to support it was worth it :)
     
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