cooker installation

[Klien]

Thanks John.. will have to read on that.

 

[JohnW2]

Thanks John.. will have to read on that.

You're welcome. The concept of 'diversity' is based on the fact that it would be very rare for all bits of it to be 'on' at any one time (heating elements go on and off with thermostatic control, even if they are all switched on).

For cooking appliances, the guideline is "the first 10A of current plus 30% of the rest". Hence, if one calculates at 230V, your 7,600 kW cooker would take a maximum of about 33A - so, applying diversity, one is allowed to consider it as a load of 10A plus (30% of 23A), namely about 16.9 A.

However, as I said, I'm not sure that helps you all that much (other than to indicate that a 20A MCB and 2.5mm² cable would theoretically probably be adequate), in terms of what you've told us about the instructions, since even 16.9A is too much for an FCU (for which largest available fuse is 13A).

Kind Regards, John

 

[Klien]

Yea makes sense that John - was also thinking about resistance of wires & that there will be some losses somewhere. I have already purchased a 35A cable & it appears that circuit breaker fuse is rated @ 32A.. Will it make a difference if size of cable is higher than req?

 

[JohnW2]

Yea makes sense that John - was also thinking about resistance of wires & that there will be some losses somewhere. I have already purchased a 35A cable & it appears that circuit breaker fuse is rated @ 32A.. Will it make a difference if size of cable is higher than req?

No, that's not a problem. Provided that the cable's capacity is not less than the rating of the protective device (your 'breaker'), that's fine. In fact, as others have said, if you really do have 6mm² twin & earth cable, the capacity of that is a going to be a lot more than 35A - but that's still fine.

Kind Regards, John

 

[Klien]

Cheers.... Its just confusing about the cable as that is what the label on reel & shelf says... still, thanks

 

[PrenticeBoyofDerry]

I'm a little surprised that no-one has mentioned diversity. By my reckoning, a 7,600 kW cooker amounts to some 16.9A after diversity if one calculates at 230V, 16.5A if one calculates at 240V. Still too much for an FCU, though.

I didn't mention it as I did not want to confuse the issue and all the evidence that Klien has given, there was no great concern over loading with respects to the full load demand, protective devices and cable rating.

 

[PrenticeBoyofDerry]

Cheers.... Its just confusing about the cable as that is what the label on reel & shelf says... still, thanks

So am I, would appreciate a picture of it, just to ease my sanity/insanity!

 

[JohnW2]

I'm a little surprised that no-one has mentioned diversity. ...

I didn't mention it as I did not want to confuse the issue and all the evidence that Klien has given, there was no great concern over loading with respects to the full load demand, protective devices and cable rating.

Fair enough, but I was attempting to give 'pre-emptive reassurance', since I was half-expecting the OP to express a concern that his '33A' cooker was being run off a circuit which had a 32A MCB.

Kind Regards, John

 

[JohnW2]

Cheers.... Its just confusing about the cable as that is what the label on reel & shelf says... still, thanks

So am I, would appreciate a picture of it, just to ease my sanity/insanity!

Indeed. However, if it is 6mm² T+E, although it's obviously a bit silly to label it with a 'current carrying capacity' (given that it varies so much according to installation method), maybe they chose what they regarded as a 'fairly conservative' figure? 6mm² T+E has a CCC of 35A (as quoted by OP) with Method 102, and an even lower CCC with Methods A, 100, 101 & 103.

Kind Regards, John