Memera 2000 40 amp b mcb

[mcat74]

I have a kiln, 7.6kw 230 volts.

I understand that 10mm twin core wire connecting to a new 40amp b mcb should work.

But googling some are saying that 6kw is the max for a memera 2000 mcb?

Any ideas. Should I be ok.

 

[flameport]

40 amps at 230 volts is 9.2kW, which is obviously more than 7.6kW.

 

[mcat74]

Exactly so why are people saying 6kw max on the mcb? Makes no sense right and I should be ok as 10mm wire and 40a mcb should be more than enough

 

[Murdochcat]

Exactly so why are people saying 6kw max on the mcb? Makes no sense right and I should be ok as 10mm wire and 40a mcb should be more than enough

Which all depends on the installation method of the cable ...

 

[bernardgreen]

I have a kiln, 7.6kw 230 volts

In the UK, the declared voltage and tolerance for an electricity supply is 230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts.

If the supply voltage is the maximum 253 then the kiln will be taking 8.36 kW ( 7.6 / 230 ) x 253 which is 33 Amp.

Running an MCB for prolonged periods at more than 75% of rated current can make the MCB hot enough to affect the operation of adjacent MCBs

 

[RandomGrinch]

If the supply voltage is the maximum 253 then the kiln will be taking 8.36 kW ( 7.6 / 230 ) x 253 which is 33 Amp.

I make that 36.3A and 9.2kW as the resistance would remain at 6.97Ohms.
Where am I going wrong?

 

[EFLImpudence]

Nowhere. Correct.

Exactly so why are people saying 6kw max on the mcb?

Some people say the world is flat. I saw something on the internet once which was wrong.

There is no maximum for such things.

Makes no sense right

and I should be ok as 10mm wire and 40a mcb should be more than enough

Yes, literally more than enough as in too big and a waste - unless you have installed it in unfavourable surroundings.

 

[bernardgreen]

Where am I going wrong?

You did not go wrong. I went wrong. I left the square out of the formula

( 7.6 / 230 ² ) x 253 ² = 9.19 kW

 

[JohnD]

The actual voltage in your house us most likely around 240v

(Test it and see)

Which for a resistive load like a kiln will put the current up.

 

[mcat74]

So running wire from one room with the circuit breaker/mcb board into a garage behind the plasterboard for about 10 metres.

Looking at gettng one of two kilns. One is 7.5kw 230v the other reads 240v/29.13a/7kw.

I have a memera 2000 board.

If I'm right I concluded that a 40amp mcb type b with 10mm twin core cable would be ok?

Best wishes

Michael

 

[davelx]

Is there perhaps some confusion with the 6kA breaking capacity of the OPDs in domestic CUs?

 

[EFLImpudence]

Ah, well done.

I didn't think of that.

 

[JohnD]

Is there perhaps some confusion with the 6kA breaking capacity of the OPDs in domestic CUs?

I have some Memshield 2 MCBs and RCBOs, which fit.

 

[mcat74]

Is there perhaps some confusion with the 6kA breaking capacity of the OPDs in domestic CUs?

Yes this is the thing. I worked it all out upgrading from 6 to 10mm and a 40amp type b mcb. Then someone said the mcb has 6kw max. These kilns are 7 to 7.5kw, so what would I do?

 

[EFLImpudence]

No. It is 6kA.