What's 15A? As I said, the self-cleaning cycle is 8.7 - 10A and, as for actually cooking, if one accepts application of the concept of diversity )which apparently yoiu don't), then that's about 11.7A (after diversity).Ah whoops. Missed the h... It’s still 15A though.
Such an oven would not have only one element.
If (far from impossible - and certainly can't be 'discounted'), one switched on all of the 'rings' and oven(s) simultaneously from cold, then all would be 'on' for as long as it took them to 'get up to temperature'
They would certainly cycle on and off, but you couldn't guarantee that there would not be times when all, or most, were on. The 'standard'; diversity calculations must therefore be considered to be acceptable even if that 'worst case' happens.
One can't, in the sense that you are trying to do. However, as I keep saying, one can have 'diversity over time' as well as 'across loads' - i.e. one can consier the average load over a 'reasonable' (say 30 min) period of time. I fairly recently illustrated (see here) that in relation to my ('single element) 1.7 kW fat fryer, the average draw over the first 15 mins (from cold) was 1,200W, and that settled down to about 600W (and remained at that level thereafter) within the next 5 minutes or so. Extrapolating from that to a ('single element') 3.6 kW oven, one might expect that the average over any 15 min period would quite rapidly settle down to about 1,270 W (i.e. around 5.5A) ......
I respect your view but, as I suggested before, by saying that one has to consider the maximum instantaneous current, rather than the after-diversity (i.e. 'average') current, you appear to be effectively rejecting the application of diversity.
Fair enough, and thanks for confirming that you would not apply diversity.
That's not how it works.
I realise that, and I'm grateful for your giving us your professional opinion. The 'hypothetical questions' have been my attempt to gain a fuklkl understanding of what your professional opinion (as regards the application of diversity) actually was.
I was not suggesting that the oven would be supplied through a 13A plug. What I was asking was, if the oven and a hob were hardwired into the same circuit, whether you would apply diversity when designing that circuit and, if so, whether you would include the 3.6 kW of oven load in your diversity calculation.
As EFLI has explained, you have got all that entirely wrong.
Are you suggesting that a fire could result from ~15A flowing through a 13A fuse (even if for a long period)? If so, I wonder if that has ever happened (particularly given that it takes ~22A to blow a 13A fuse).
As far as the cable is concerned, in the situations we have been discussing, it has been assumed that the cable would be adequately protected by the circuit's protective device. This means that the cable is considered to be 'safe' no matter what current flows through it for how long, for whatever reason - since the protective device will cut off the supply if the magnitude/duration of the current reaches a level which might damage (or seriously overheat). The concerns voiced therefore relate only to the currents that will sometimes flow through protective devices, plugs/sockets, accessories etc.
That is precisely the point. Concepts like diversity are statistical in nature, so one could describe them in lay terms as 'intelligent/informed gambles' - but they are gambles based on what are (or were) believed to be reasonable/sound foundations, and have stood the test of time. However, as you imply, there will never be certainties in a probabilistic situation.
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