as stated in forum.velleman.be/viewtopic.php?t=964,
a cat5 cable can be used as combined data and power line (where power is prefereably used with 2 wires per pole).
what is the max cable length for transporting data over the Velbus using this cable
what is the max cable length for supplying power using this cable.
We have no experience with max. cable lenghts.
In our building, there are kilometers of cable, without any problems.
We have separate power supplies for each floor, to avoid voltage drops.