[Solved] Is 4x1mm2 cable instead of 3x1.5mm2 a good idea for lighting?

Hello.
Is 4x1mm2 wire instead of 3x1.5mm2 a good idea for lighting?

Maybe I can explain why I want it that way first. I am in the process of shopping around for laying out the wiring in the house. I want to do it in a star topology so that in the future I will be able to do some kind of automation in the house. I don't want dimmers, so I've come up with the idea of having two bulbs for each light point (which will de facto also be a separate circuit at once). Normally, I understand that a 3x1.5mm2 cable would go to the double pushbutton and then a 4x1.5mm2 cable would come out of the pushbutton (although I think it could be smaller) to the chandelier, which has two separate lighting options. As I want to have automation I will dispense with the standard push buttons and the control of what is lit will be "in the switchboard" so to speak. The 4x1.5mm2 wire is more expensive and the 4x1mm2 wire is almost the same price as the 3x1.5mm2 wire.

In addition, it seems to me that with a 4-core cable I have the possibility of doing the lighting directly on direct current, e.g. 24V keeping the same scheme, that the light point has two bulbs lighting independently, because I have two pairs of wires + and - (dc probably does not need earthing).

With the current wattage of the bulbs, this cross-section of wires should not be a problem (especially as the circuit will consist of a single light point). From what I have read, even 0.75mm2 would suffice, but it is accepted that 1.5mm2 is used because it has greater resistance to mechanical damage (some wire breaks).

Now my concern:
Maybe I'll point out right away that I'm not going to stitch it up but want to hire an electrician, I'll lay out the wires myself.

1) How do I protect this as it will be on AC, I didn't see 2F differentials as it will actually be a bit like a two phase circuit then (earth, neutral, phase 1 and phase 2)?
Two 1F differentials somehow bundled together? Is it even possible to protect this well?

2) Similarly, when this will be on DC, I understand you would also need something anti-short-circuit? Although I must admit that doing the lighting as a DC circuit I understand less.
The way I see it is that there is a 24V power supply in the switchgear and to it there are somehow, just as there are rather no separate outputs for each circuit just one, to which all lighting circuits are connected via some relays. And now the power supply gives 24V all the time, but when I switch on one bulb, say 12W, it should give 0.5A, then I switch on another 12W, and again another 0.5A. How will it know to increase the current and by how much. What if I switch on a 6W bulb now, will it know to increase it by 0.25A? Is this because, for example, a 12W bulb has half the resistance of a 6W bulb and this will happen automatically, because the power supply will adapt to the resistance?

3) All kinds of connectors, inputs in some differentiators are probably designed more with 1.5mm2 in mind and won't 1mm2 sit "loosely" there? You probably need to take this into account when buying accessories or at least buy some sleeves to make 1mm2->1.5mm2 so that it sits nicely and the contact is decent.

Are there any hazards I haven't thought of? Maybe this is a silly idea in general and it is done differently?

AI: What will be roughly the lengths of the individual lighting circuits and what will be the maximum wattage (W) per circuit? .
I think a maximum of 15m and a total power of probably a maximum of 30W.
AI: Do you eventually plan to power the lighting from the 230V AC mains, from a DC power supply (24V), or do you want to be able to have both solutions? .
Both solutions.

Not possible because 1.5 mm² is the minimum permissible cable cross-section for the supply of electrical appliances in homes, due to mechanical strength.

And you write that it was supposed to be cheaper and you are combining with DC like a horse uphill.

So as I understand it, I won't get a house acceptance if I use 1mm² wires for lighting? Poorly .

Yes with DC it's a bit of a combination, but as a layman I see it like this. If I have DC power, then the LED bulb doesn't have to have any electronics, meaning it's cheaper and in my opinion more durable (less things can break in it). With AC it's the LED bulb that has to have electronics, meaning it's more expensive, more chance of breaking and probably the efficiency of its power supply (because as I understand it, it has a mini power supply that does AC->DC) is certainly poor and on top of that it probably heats up more, so more current loss, than the combination of a decent power supply and a normal LED bulb.

Well, but I don't know, I certainly don't want AC and then somewhere closer to the lighting a DC power supply, as I won't have false ceilings so have nowhere to bury it. Also, a separate power supply for each circuit is also a cost. If it's lame, I'll use 230V AC powered LED bulbs and that's it.

With 24V dc you would have to give much thicker wires because the currents would be higher. And double wiring of everything... and also some central power supplies, a big distribution box, maybe even with ventilation because it heats up. But the question is why, when now every led lamp has its own power supply inside?
Without electronics, it won't be cheaper because you'll still buy with a power supply which you'll then throw away (ignoring the money you'll spend on the DC installation). Besides, efficient led lights don't work on 24V but on e.g. 200V DC, depending on the configuration....
I am not familiar with home automation, but wireless communication is convenient and can be used for a large number of simple devices which do not require a large bandwidth. It is only worth ensuring that power is available at all times in the junction boxes in which you place the 'dongle' (and not, for example, only when the light is switched on using a mechanical switch).
Alternatively, an Ethernet connection could be made to at least some of the junction boxes which would be used to control nearby receivers (such local mini-centres) - although I don't know if this makes sense, as it's difficult to buy anything cheap that has Ethernet at the moment, everything runs on WiFi. Maybe in combination with PoE it would make sense - then when installing various automation gadgets it would be possible to power them from Ethernet and avoid installing a separate power supply in each 'control panel', at the same time ensuring connectivity, but in the end it will probably turn out that you need radio because you didn't foresee this or that and the cables aren't led where they should be (but there are plenty of unused ones somewhere else). Certainly Ethernet/PoE makes sense in the case of IP cameras; it is worth thinking about in advance, as they are usually installed in places where neither power nor network have been foreseen.

gurth83 wrote:

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Yes with DC it's a bit of a combination, but as a layman I see it like this. If I have DC power then LED bulbs don't have to have any electronics, which means they are cheaper and in my opinion .....

Then maybe this layman should at least finish primary school. There will be physics and mathematics there, which will enable him to count the cross-sections of wires to get to know the documentation a little.
Because, as colleagues have rightly pointed out, the lower the voltage and the power of the device the higher the current flowing in the circuit, which follows from the law he has, but unfortunately you need to finish primary school to know at least this law. On 24 v dc there are no electronics fridge no no super. Well, let me tell you, it's got practically the same one. Because, after all, the standard diodes used in such devices operate at between 3a 3.5V. Apart from the occasional power LED they are not used, it is cheaper to give 10 diodes for 50 gr each than one for 15 zł. Such a detail as energy conversion, i.e. the change of voltage from 230V to 24V, which is obligatory in Poland, does not take place for free.

gurth83 wrote:

As I have a DC supply then the LED bulb doesn't have to have any electronics, meaning it's cheaper and in my opinion more durable (less things can break in it). With AC, the LED bulb has to have electronics, which means it is more expensive, more likely to break and probably the efficiency of its power supply (as I understand it, it has a mini power supply that does AC->DC) is certainly poor and on top of that it probably heats up more, so more power loss than the combination of a desirable power supply and a normal LED bulb.

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And this is where you are wrong. Every 'LED bulb' has an LED driver in it. And their lifespan depends primarily on the power given off by the LEDs themselves. They are the ones that overheat and get damaged in the first place.

On the other hand, using 24VDC and a decent power supply, i.e. more power, is just trouble because:
- it has to be switched on constantly - it consumes several watts of power even when idle
- thicker cables
- in the event of a short-circuit, I prefer not to think about how to interrupt the direct current - I don't know if you are aware that electrode welders already weld at around twenty volts mostly DC.

In my opinion you are pushing yourself into trouble and also costs and a huge risk of e.g. fire.

That is, for your own peace of mind and total cost, it is better to pay extra for the 4x1.5 cable and 230V LED bulbs than to combine with central DC.
Thanks for your help (leaving out one troll looking for attentions).

4x1.5mm2 cable and 230V AC LED bulbs.