Questions about KNX components

[kimberlyfal]

Hello,
I want use KNX switches in a project that are less noticeable than the Loxone switches. I will also have Loxone switches in some places.
Do I need to have a separate wire loop of the Loxone Tree cable installed for this? Can it be connected to the same wire loop?

Thanks in advance!

[Labmaster]

KNX is KNX and not a Loxone Bus.
If you speak about the "standard" KNX you usually speak about KNX TP (twisted pair).
KNX TP is a system on its own where power (something between 22V and 29V) and data modulated on top of it are on two wire only.
That is possible as the Protocol is a KNX own system that was developed for making this possible and has nothing to do with Loxone Tree Bus what from the physical point of view is in fact a CAN bus.
So Loxone Tree needs 4 wires for Power and Data not only 2 as KNX TP .

The KNX spec. even gives you a very specific recommendation using a specific KNX TP wire type either YCYM2x2x0.8 or JY()ST)2x2x0.8,
where the first one is specified been tested up to 4000V and the second one only tested up to 2500V (according to EN50090)
This would mean that the first one is allowed to be placed directly next to a (230V) AC cable where the second one not.

Some people mixed both system KNX-TP and Loxone Tree in one cable. For this you need at least 6 wires and therefore a LAN cable type might be possible. One problem that could appear is, that the wire diameter of a standard LAN cable (AWG28, AWG26, AWG24) is something between ~0,3mm and ~0,5mm and this might make loose connection at the default KNX device connectors (Wago 243-211) as they are specified from 0.6mm to 0.8mm.
So even if using AWG24 LAn cable (the biggest with 0,5mm diameter) a loose connection could be possible.

Not again mentioning the official KNX specifications that only recommend the official KNX cables beeing used.

[Jan W.]

Do I need to have a separate wire loop of the Loxone Tree cable installed for this? Can it be connected to the same wire loop?

Yes, you need separate cables for both systems as explained by Labmaster. Both Systems (tree and KNX) are low-speed busses that deliver power to components that are not power-hungry. Tree is able to deliver some more power e.g. to lights. I would recommend to use specific cables for tree and KNX to be 100% compliant, however both may work with cables from the other system and even CAT6 or CAT7 if the number of devices is low and the length of cables is small.