I would not worry about the 2400/2300W ratings. The 2400W rating is from the days when we used 240V and the 2300W one is for the new fangled 230V that we now use.
Oven tripping RCD intermittently.
- Thread starter yakheart
- Start date
I would not worry about the 2400/2300W ratings. The 2400W rating is from the days when we used 240V and the 2300W one is for the new fangled 230V that we now use.
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The difference between 2,300W and 2,400W is certainly totally unimportant, but the explanation for the difference cannot be quite as straightforward as you suggest. An element which produced 2,400W at 240V would produce only about 2,200W (not 2,300W) at 230V.
Kind Regards, John
That is true if you are treating the old element as a fixed 24ohm resistive load (dunno what the resistance alters by when heated).
But as you noticed the point I was making is that the change from 2400W to 2300W is not important and the OP need not worry about it.
But as you noticed the point I was making is that the change from 2400W to 2300W is not important and the OP need not worry about it.
Indeed. In practice, the resistance would be a bit less with the lower voltage (hence lower temperature), so the power would not be quite as low as 'fixed resistance' calculations would suggest.
Again, indeed - we both made that point.
Having said all this, the majority of manufacturers (of most things - showers, immersions, kettles, cookers/elements etc.) seem to still quote power at 240V (to make then sound 'more powerful'?) even though we notionally (but not in practice) have a 230V supply!
Kind Regards, John
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Why?
The temperature will be governed by the thermostat and therefore the same.
Surely it's not a 'change' but a different element.
Are we not talking about the maximum power consumed by the element - not the 'in-service' power consumption when it is thermostatically controlled? That's what I had always assumed the 'power rating' of a cooker element (or whatever) related to - am I wrong?
As you know, I didn't write that - but the 'change' has surely been in the description/specification of what Neff are supplying for this oven. We can but speculate whether the element has actually changed, or whether they are merely quoting the power at a different voltage for an unchanged element.
Kind Regards, John
The maximum power must be when cold - i.e. a 2400W @ 240V will be measured at 24Ω when cold and so converting the wattage to 230V will be as calculated.
I realise it wasn't you but the OP said his present element was 2400W but now he can only find 2300W ones.
It was assumed that this was because of the change in nominal voltage but I would think this is still quoted at 240V, merely a slightly lower powered element.
I recently replaced one of mine.
It was 2500W originally but I could only find a 2000W one.
The oven still gets as hot, presumably taking a little longer to get to temperature.
Now you've got me thinking! If that's how the power of elements is specified, then, at operating temperature, they are going to have a lot less power than one might have 'expected' (which might have yet more impact on some of our 'diversity' discussions!). I'm not sure what material such elements are made out of but, fortunately, the resistivity temperature coefficients are roughly of the order of 0.004 per °C for a wide range of metals (including copper, tungsten and aluminium). That being the case, an element with a resistance of 24Ω at 20°C would, if I've done my sums right, probably have a resistance of around 46Ω at 250 °C - hence a power at 230V of only about 1150W (or about 1250W at 240V). Is that your understanding of the meaning of these 'specifications'?
I agree that is quite probable - but, as I said, without more information we can really only speculate as to whether it is a lower-powered element or the same element with the power specified in some changed fashion.
Kind Regards, John
Oh. I didn't mean to do that.
It can only be so.
I don't know the figures but measuring the current of a shower, for example, when working gives a surprisingly low reading.
I wouldn't go that far. If one took that method of specifying 'wattage' to it's logical conclusion, a 100W incandescent bulb would probably be described as a 500W one! As I said, you've caused me to think about this for the first time, but I remain unsure of what 'specified wattages' actually mean in relation to a resistive load which considerably increases in temperature in use. You may be right, but .....!
Interesting. I wonder if anyone has any figures? If that's true, and given that showers get up to operating temperature very rapidly, maybe we are being grossly over-generous in the cable CCCs we require for them?! Mind you, with things like showers (and immersions etc.), the temperature rise of the heating element (hence reduction in power consumed) will presumably be very much less than with a cooker element.
Kind Regards, John
Ah. I don't think the same goes for incandescent lamps.
It may be the other way round as the resistance of the filament when cold bears no resemblance to its wattage.
Again, I don't know but presumably the manufacturer can only produce an element to a certain resistance and then calculate and quote the other perameters or vice versa.
Perhaps they should also quote the temperature at which the values apply or will it be at the standard 20°C?
I think we are both wallowing around in ignorance here! You could just as easily have written "...resistance of the element when cold bears no resemblance to its wattage.", couldn't you? It's a question of what conventions are used - which, as you imply, probably varies between different types of product.
Indeed. If something varies markedly with temperature, then one would surely expect to be told what temperature the quoted figures related to. It could be that, for convenience, they quoted wattage "at normal operating temperature", but you are suggesting (probably correctly) that whilst that is probably true for incandescent bulbs, it is probably not true for cooker elements.
I have to say that I find this all rather odd. A cooker element heats up pretty quickly, and spends most of it's 'on time' close to its operating temperature. If it's wattage at that 'normal operating temperature' is, as I suggested, ~1150W, I'm not sure that it's all that useful to call it a "2300W" element, is it?
Kind Regards, John
I should have said "stated wattage"
That would seem to be the case.
That may be true but if it were the other way round you would be complaining that this 5A element is actually 10A until it heats.
I don't suppose it matters with a lamp.
I'm not sure that I necessarily would complain about the element, any more than I would about the lamp. We all know that 'start-up' currents are often much greater than 'running' ones, for a wide variety of loads.
If what you are saying (about "stated wattages") is true, then it clearly means that the normal power consumption of a cooker is probably far less than we would expect, even after diversity has been applied, since all the elements which are 'on' will spend most of their time close to 'operating temperature'.
Kind Regards, John
Yes but the 'stated wattage' comment was replying to your query regarding the light bulb, i.e. 100W incandescents are not 576Ω when cold.
Presumably they are when hot. How hot do they get?
Presumably they are when hot. How hot do they get?
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