Number of wires in KNX/EIB installations – taken from the cable reel.

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It’s just that I don’t use 3x4mm² instead of 3x2.5mm². Instead of 3x, I use 4x.

Why are you using 4x, thereby increasing the cost, instead of 3x?

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The fourth wire is a spare, allowing for future expansion with new features.
The best example is RGB LED lighting, which requires four wires.
Upgrading a 15-year-old installation basically involves removing the old light fitting and fitting LEDs plus a controller.
In the case of sockets, a four-core cable allows you to control specific sockets.
For example, in the living room, we might have a socket that’s on 24 hours a day, connected to an aquarium, and next to it a controlled socket that switches off the TV set at night or whilst we’re on holiday.
In the children’s room, we could have an uncontrolled socket, to which, for example, a lamp is connected, and next to it a socket to which a computer or TV is connected, which we can switch off, for example, via a smartphone.

Wouldn’t it be better to lay a 20-core cable?
How much spare capacity would we have then?
Right, I’ve gone a bit over the top.
However, I’m wondering what you’ll do if you need to install another circuit with additional control?
Is there any point at all in leaving a spare fourth core?
In lighting, it’s understandable that 4- and 5-core cables are needed, but in the case of sockets, this is a typical waste of resources, because 2.5 mm² 4-core cables are expensive due to their low popularity and limited sales, and, what’s more, you’re forgetting that with such a cable, one of the cores will act as a common conductor – usually the neutral. Explain to me how you’ll handle the power distribution?
After all, you can’t just connect these cores to two separate phases and use them to power single-phase appliances. The total power draw from both conductors is limited by the capacity of the shared neutral conductor, and for this reason you cannot load each conductor with 16A from a single phase, as the capacity of the shared neutral conductor would be too low.
I believe that running 4-core cables to sockets is simply an ill-considered waste. For the money spent on that extra cable, you could buy more 3x2.5mm² cable and install separate circuits where they’re needed. If, in the future, you need to control sockets or lighting, you can easily add components to the junction boxes that allow for control via radio or through the power cables.
Looking ahead, when building a house, you can run a data bus using a 2-pair twisted pair cable or even a standard 4-pair UTP twisted pair cable. It will still work out cheaper than installing a 4-core cable.
As for RGB control in the case of LEDs, this is not a problem either, as there are ready-made driver modules that allow control via the bus, by radio, or via the power supply cables.

Plumpi wrote:

Is there any point in providing a spare fourth wire at all?

In an LCN system – yes. The fourth wire (red!) is a signal (control) wire.
An installation set up in this way can gradually be converted into a smart system.
But whether this makes sense in detached houses or flats – I’m not sure about that.

The thing is, this system is rather unpopular and outdated. What’s more, it creates a number of problems relating to the decoupling of the neutral conductor. The need to use isolation modules for individual circuits protected by separate RCDs increases the cost of building the infrastructure. So what was supposed to be cheaper turns out to cost just as much as other systems.
Somehow, this system doesn’t really convince me.
Running a separate twisted-pair cable probably offers more possibilities, as, in fact, it can also be used for this system as a transmission bus.

Hello

Mate, sort yourself out and clarify your thoughts, because I’ve lost track of what you’re on about.

In post 113 you wrote:

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....
It’s just that I’m not using 3x4mm² instead of 3x2.5mm². Instead of 3x, I’m using 4x.
....

Post 117:

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In the case of sockets, a four-core cable allows you to control a specific socket or sockets.
For example, in the living room, we can have a socket that’s on 24 hours a day with an aquarium connected to it, and next to it a controlled socket that switches off the TV equipment at night or whilst we’re on holiday.
In the children’s room, we can have an uncontrolled socket to which, for example, a lamp is connected, and next to it a socket to which a computer or TV is connected, which we can switch off, for example, via a smartphone.

In post 121, you write:

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It’s possible, but the clattering of the relays in the living room isn’t exactly pleasant.
Control via the power cables is highly debatable, and practically nobody does it.

Could you comment on that?

As for the switches you’ve shown, our own Polish company offers devices that are two or three times cheaper; they don’t currently control audio systems, but it’s only a matter of time.

Perhaps my colleagues have forgotten, but the discussion in this part of the thread begins with post 92.
In post 94, however, I explained exactly what (which theory) is the reason behind it.
So I would ask you to at least roughly ‘stick’ to this line of argument and either confirm or refute this theory.

kkas12, this thread has strayed from the topic quite a while ago – if possible, could you please separate the topics related to IB?

Mate, as usual, in your typical style, I’ve heard your reply.
So what’s the situation? Do you have a fourth wire laid as a spare, which could be used, for example, to control IB sockets, but you’re not using it because the modules in your living room keep tripping? Yes or no – is it difficult to answer?

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kasprzyk wrote:

Mate, as usual, in your typical style, I’ve heard your reply.
So what’s the story? You’ve run a fourth wire as a spare, to be used for controlling IB sockets, for example, but you’re not using it because the modules in your living room keep tripping – Yes or No – is it hard to answer?

I simply don’t believe it.

I see – you don’t believe what you’re writing; you keep contradicting yourself.

The thread hasn’t been split off yet, but since you’ve continued it, I’ll reply here. You wanted to show off with the IR remote modules in Nexo, but you’ve failed again.

Have another read on how these modules work in the Nexwell system, then go back to my reply about the programmable switches/buttons, and you’ll realise that this feature hasn’t yet been implemented in the device I’m describing.

The prices aren’t just plucked out of thin air, mate; they should be available to the general public before long.

So am I to understand that, for you, using a 3x4 mm² cable is already a sign of bourgeois snobbery and a waste of money – money that everyone is short of – only for you to go and write straight away that you yourself use 4-core cables, just to be on the safe side (just in case)?

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Are you having trouble understanding what you’ve read?
Although, on the other hand, if you think there’s no difference between a traditional electrical installation and an IB/ID installation, that’s your problem.

No, not at all
I just wanted to make sure, as I wasn’t certain I’d understood correctly.
After all, it’s obvious that in a smart installation we can afford to build in a bit of extra capacity, just in case, for the future, (...), whereas in a standard installation there’s simply no room for that.

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So is it this module that controls the AV system, or is it that bit of metal sticking out of the ceiling?

Yes, that ‘piece of metal’ sticking out of the ceiling controls the AV equipment, but that ‘piece of glass’ I mentioned doesn’t yet.

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Really? Very interesting. So how much does a Nexwell distribution board actually cost? As usual, it’s been top secret for the past six years.
Anyway, it doesn’t change anything.

I don’t know, I don’t use their switchboards – wouldn’t it be better to give them a ring? Or do they not like you there either?

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PS.
Spare us the sarcasm – it doesn’t come across at all.

That’s all from me

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So I’ll ask again: what benefits will you gain from using a 3x4mm² cable instead of a 3x2.5mm² cable on the section between the distribution board and the room?

I’ll leave aside the financial circumstances of those with standard installations and ID systems. After all, this isn’t a financial forum.

The problem with this whole discussion is that the benefits have already been outlined – and not just once, unfortunately:
Or:

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Are you having trouble understanding what you’ve read?

Or perhaps these arguments simply aren’t enough for you. If the latter is the case, then unfortunately, even if I were to write a detailed essay on the potential advantages, you could simply dismiss it with your counter-arguments – too expensive/too much work (as you’ve been doing so far, in fact).

Also, if you were able to take a step back from this discussion, you’d notice a certain pattern and understand the point of my question posed two (of my) posts ago.

At this point, I could ask him to outline the benefits of using a fourth (spare) core in smart installations, and counter every argument by saying that it doesn’t justify the increased cost or the added difficulty in laying the cable.

The problem is that neither the use of 4 mm² cable in traditional installations nor the use of a fourth spare core in smart installations is standardised; consequently, the discussion is limited to an exchange of arguments, the weight of which depends on individual perceptions of the importance of certain issues.
For example, for one person, the priority will be to maximise safety, regardless of the financial outlay, whilst for another, the priority will be to keep costs as low as possible whilst maintaining the necessary minimum level of safety.

Furthermore, returning to the original topic, namely the question: “Is it possible to use a 3x4mm cable on the section between the distribution board and the room (just in case), and is this justified? Thank you and best regards. Michal”
It’s not clear-cut, as one of my colleagues has already pointed out. Would you advise the author against this solution if it turned out that these sections are straight, there’s no problem with the grooves (because the walls are terribly crooked and the plasterboard will have to be replaced, leaving a large gap between the board and the wall) and the author already has this cable? Or would you still urge him to buy 2.5 mm², even though this would increase the costs?