A question that has been on my mind lately, and one I haven’t been able to clarify yet since I don’t have an electrician, is the following: What does a “standard” electrical installation (not KNX or similar systems) look like during the shell construction phase when the cables are routed inside empty conduit on the rough subfloor? Let’s assume that in room X there are 6 electrical outlets, 1 light fixture with a switch, and 1 switch for an electric roller shutter. Does a single cable run from the distribution panel into room X and then get distributed throughout the room via flush-mounted boxes? Or do the cables run individually from each load back to the distribution board? So, in this example, would there be 2 cables for the two switches and 1 cable for the six outlets wired in series? Is this approach repeated from room to room, or are separate cables grouped together at some point?
Electricity flows in an "analog" manner, meaning without protocol headers, and can therefore only be selectively addressed behind switches. The trend towards centralized control systems is increasing, so nowadays I would generally prefer to wire energy distribution in a "star" configuration.
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danixf schrieb:
Technically, it works. At least partially. But that's not how it's usually done. You would forcibly have two circuits in the same junction box. If they’re on different phases, it’s almost a short circuit.I don’t quite understand that yet. Where is the problem?
The only possibly wrong aspect is having to use 2.5mm² (approximately 3 AWG) cables in that setup. Normally, 5 cables of 1.5mm² (approximately 15 AWG) should be sufficient, especially given the lengths mentioned.
guckuck2 schrieb:
I don’t quite understand that yet. What is the problem?
The only supposedly incorrect part is having to use 2.5mm² (about 14 AWG) conductors for that setup. Usually, 5x1.5mm² (about 15 AWG) should be sufficient, especially for the lengths mentioned. As I said, technically all of this works, but whether it complies with standards—I believe it doesn’t.
In new construction or during renovations where everything is open anyway, this is definitely not how it’s done.
If it is done, there must absolutely be a disconnect device, for example an RCD (residual current device) that disconnects the circuit in all poles, but then you might as well run everything on one circuit and avoid this discussion altogether.
Try searching for “one cable, two circuits.” This is often a controversial topic.