Sizing Cooker fuse / diversity...confused

[sparks1234]

Yes but I think you have just worked out the diversity on the installation rather than the cooker.

 

[scotsparky]

Diversity statement has just been removed.

 

[Wotsit]

What you are suggesting by "bang in a smaller breaker it will be all right mate" can lead to a potentialy overloaded circuit

And the post about diversity is utter rubbish



That part.!

Ok, From the BRB we are told to comply with reg 433.1.1 by putting in a smaller protective device than the design current we do not.

If you follow your calculations through It=In/CaCgCiCc
using a reduced value if In your Value for It is incorrect, leading to the incorrect selection of cable size
Incorect cable size of course will affect you disconnection time

Zs=Ze(R1+R2.Cf.L/1000)

 

[Mr Mark Sparks]

wotsit

will the 32a mcb be ok was the question
most people gave common sense answers for things to try to help the guy out
its all well and good quoting the regs and we shoulld follow them
however nobody said he should try anything dangerous just saying he could try the 32a and see how it goes
before he gets invoved with possible new circuits
another example of this must be shower upgrades im sure there are many on a cpd that is underated but run perfectly ok because these thing seldom run at full load


ps this is what the forum is here for discussion and debate and your post is as valid as any of the others

 

[scotsparky]

Wotsit. I agree with the maths not a problem.

But as its a new cooker with a larger load its the cable size thats a problem not the mcb?

 

[baldsparkies]

Wotsit,
I am going to make a very bold statement, 8 meter run of 6mm t/e clipped direct 40A BS EN 60898 typeB protective device complies with all current regs and no problems with a 9kw load or volt drop

So what exactly are you trying to prove here ?? after all the resitivity of a conductor is proportional to its cross sectional area, and inversely proportional to its length provided the temperature remains ambient. But then you already know that

 

[andyb]

The cable is not a problem , 6mm clipped direct is rated at 46 amps.

So the design current of the circuit will be 32 amps, I think that if you were to put a clamp meter on the circuit and turn all elements on the cooker you will get nowhere near 40 amps. My guess is about 20 to 25 amps.

 

[aaronstuart]

I've certainly opened up a bit of a debate, and don't want to cause ill feeling between anyone, as i think this is a fantastic forum and use it regular.

Sorry.

 

[baldsparkies]

Thats the one Andy, clipped direct it all works out on the calcs 40A mcb is a go,cable is protected and your cooker will never get near it anyway

 

[Mr Mark Sparks]

Buy Fuses Online from The Fuse Company

mcb anyone

aaronstuart its what we are here for

 

[acat]

Arron dont be sorry and dont stop asking questions thats what this forum is all about and we all learn from it some people tend to get a bit excited thats all


Chris

 

[sparks1234]

Do you ever get the feeling some people think too much?

 

[Wotsit]

So should we forget about the BRB and just do what we feel like? Because we know better? I know its not law but the book is there for a reason.

To me one reg is as important as another, esp if giving advice.

Pease read 433.1.1

 

[baldsparkies]

Dont worry Arron,
Your a thinking electrician and there is nothing wrong with that.calcs don't always reflect the real world though use them as a guide.

 

[Spudnik]

Indeed.

What has been posted about diversity are valid points.

It is well known that this can be applied to a cooking appliance.

Therefore if the calculations allow a 32A MCB to be used and the cable is suitably sized (6mm) then there is no problem.

Even 4mm is fine on a 32, but lets not go there.