"Dedicated cooker circuit with a 32/40 amp MCB"?

QTPie

Thanks Muckybucket.

Am slightly confused as details for cooker (100mm twin Britannia Delphi Induction) say 32A/40A, yet you think 50A. Are they under speccing it or am I reading their specification wrongly?

muckybutt

If it's 11.7kw 11700 watts then what they are saying is well out.

Calc : Watts divide by Voltage gives you the Amperage

so at 240 V - 11700 / 240 = 48.75A
230 V - 11700 / 230 = 50.86A

So you can see they are well out !

muckybutt

Just been looking at their info on your cooker and it does say 40A

The hob on the one I am looking at here is a total load of 10.8Kw or 45A which isn't what they say !

Dodgy to say the least !

Cable current carrying capacities http://www.elecsa.co.uk/Technical-Library/Wiring-Regulations/Inspection-and-Testing/Current-Carrying-Capacity-of-Cables.aspx

QTPie

This is the one I am looking at (can't connect to the exact Britannia page when using iPhone) - http://www.rangecookers.co.uk/britannia-delphi-100-twin-induction-product,4260.aspx

(But it definitely says 32/40A).

We are moving into a house with a Britannia Dynasty 100mm range with gas hob (on the 6mm cable, 32A MCB, hardwood floors ). I don't like cooking with gas and want to replace it with induction (hence Britannia Delphi Induction). Was hoping todo it quickly, but looks like we had better not rush into it since would need to replace cable etc...

muckybutt

QTPie wrote: »

This is the one I am looking at (can't connect to the exact Britannia page when using iPhone) - http://www.rangecookers.co.uk/britannia-delphi-100-twin-induction-product,4260.aspx

(But it definitely says 32/40A).

We are moving into a house with a Britannia Dynasty 100mm range with gas hob (on the 6mm cable, 32A MCB, hardwood floors ). I don't like cooking with gas and want to replace it with induction (hence Britannia Delphi Induction). Was hoping todo it quickly, but looks like we had better not rush into it since would need to replace cable etc...

Yes that's the same cooker I was linking to ... different colour though !

Definatley don't rush into it, as you can see from all the above what they are stating in their literature is wrong ! the calcs prove it !
With all the hobs on a 32 / 40A supply would trip out as you would be overloading the circuit.

zax47

muckybutt wrote: »

Yes that's the same cooker I was linking to ... different colour though !

Definatley don't rush into it, as you can see from all the above what they are stating in their literature is wrong ! the calcs prove it !
With all the hobs on a 32 / 40A supply would trip out as you would be overloading the circuit.

Have you applied diversity in your calcs?

Applicable load = 10A +30% of remainder of stated total load +5A extra if socket present.

Ben84

zax47 wrote: »

Have you applied diversity in your calcs?

Applicable load = 10A +30% of remainder of stated total load +5A extra if socket present.

I mentioned diversity in post three - but I think it's been missed as there's a good few posts in this thread now and it doesn't particularly jump out.

But here's the basic outcome of it - loads of electric cookers are connected to a supply and fuse/breaker that on paper is insufficient. Actual problems from this are rare however, and the worst that will happen is the fuse blows or the breaker trips. If in the unlikely event the OP has problems, they can simply be more careful how many elements they turn on at once or get a better supply for the cooker installed. Chances are however the designers have done various simulations and real world tests and know most people will have no problems with the recommended 32A.

I can see the source of the confusion as it does seem to contradict everything we usually think and do with appliance installations. But it's a special case and makes sense. People just don't cook with every element turned on at once, and there's no serious hazard from trying.

It's not that limited in real life situations either. My old electric cooker didn't allow the grill element in the top oven and the cooker element in there to be turned on at the same time, yet their wattage was added to the total. Also, turning on the main oven made the top oven very hot, so the element in there didn't have to switch on often when the main oven was in use. Meanwhile, the top oven/grill leaked a lot of heat in to the hob and vice versa. In practice, getting a cooker to draw it's total claimed wattage might be impossible in some cases, or at least very hard to do. You might manage it for a few minutes by turning on every element at once from a completely cold start. It won't be long however before they're each cycling on less and less and the average load per element is falling as the heat spreads throughout the cooker. When you get in to a big cooking session with a hot cooker the watts go much further as each one turned on makes the others work less. You'd hit some kind of equilibrium much below the actual rated wattage of the cooker eventually. That's probably how most people get away with cooking Christmas dinner on a 32A supply.