# Please review my MCB calculation for 16amp 3.5kw oven

#### pbryd

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

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.

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?
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

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.

Yes.

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

Yes.

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

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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