Replacing gas hob for ceramic - electricity question

Hello,
I've got a gas hob above an insert oven, but have decided to get rid of the gas hob because we're moving and we're going to rent the place out. The hob is in bad visual condition with knobs attached only thanks to Araldite, and we have to start paying extra money because of the rules for gas safety (maintenance etc.) so I thought I'd just go electric.
The insert oven is on its own cooker circuit, 40A, while the gas hob only is wired into a ring circuit (not the same as the cooker, obviously because the ignition doesn't need much power). There's the usual 13A socket on the cooker circuit switch. Nothing else is on the cooker circuit.
So my question: the existing oven is rated 2.3kW, while the cooker circuit is rated 40A. Using 240V as the calculation a 40A circuit should cope with 9.6kW, is that not correct?
So that leaves me with 7.3kW for the electric hob and other appliances plugged into the socket, as I presume the logical thing is to keep the oven and hob on the same cooker circuit.
Looking at the Whirlpool appliances for example they are rated around 6kW.
So that leaves me with +/- 1.3kW in excess on the cooker circuit. Of course it's unlikely that I (i.e. my tenants) will run four ceramic rings and the oven at full all at once, while still trying to boil a kettle of tea plugged into the 13A socked on the cooker circuit, however I'm wondering if this still is within the normal limits. The kettle that's there at the moment is 2.8kW...
So to stay safe: do I provide my tenants with an annoying <1.3kW kettle, get rid of the 13A socket on the cooker circuit alltogether, or replace the 40A circuit breaker with a 45A one? Are my general calculations above correct?
Thanks in advance!!!
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On Tue, 16 Dec 2008 21:02:45 +0000 someone who may be oh

down to the cooker bit at the end. That is the previous regulations, but still good. That should answer your two questions.

Why do you think the circuit breaker is provided?
Do you think that you can increase the rating of the circuit breaker without working out whether this will compromise the safety of the electrical installation in a house you are proposing to rent out? Either do the calculations yourself, or employ someone to do them for you.
--
David Hansen, Edinburgh
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David Hansen wrote:

or just post here, and Dave being the helpful chap he is will do them for you.
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Cheers,

John.

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oh wrote:

Nothing to worry about really. You can allow diversity in the calculation of the circuit capacity because of the point you highlighted about the improbability of running everything flat out (even assuming you could given the thermostatic control).
So for a 6kW cooker (or oven and hob combination) we get:
6000 / 230 = 26.1A
Applying diversity (10A + 30% of the remaining load)
10 + 0.3 * 16.1 = 14.8
Allow a further 5A for the socket on the cooker point, and you get a circuit requirement of just under 20A. The peak load is obviously higher, but you won't be able to achieve it for long enough to matter.
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Cheers,

John.

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John Rumm wrote:

As well as diversity, Ring & radial circuits can and do supply well over rated current for short time periods without harm. Theyre designed to.
NT
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oh wrote:

...whereupon they immediately stash it away somewhere because it's annoying, and replace it with a proper 3kW one, you mean? :-O
David
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Given how much more a decent ceramic hob is than an equivalent gas one, it could be a false economy.
If you have any other gas appliances, the extra cost of getting the hob checked at the same time as doing the boiler for instance is very little - 10 to 20 probably. I can't think of any other additional costs for sticking with a gas hob. The plumber would fit the new one when they do the gas check, so it would probably cost less to fit than a separate visit by an electrician to fit an electric one.
A
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Personally, I would say a "decent" ceramic hob is infinitely expensive, on account of being non-existent.
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snipped-for-privacy@sheldononline.co.uk wrote:

Arguably because (some) people prefer the instant nature of a gas hob (although others would disagree because it's harder to clean)
David
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