Does anyone know if there are wired versions of things like light bulbs, switches or sockets? Or can you only get wireless versions?
Look at things like KNX
Wired how, like Ethernet jacks built into them for a network or some other low voltage COM wires?
The only thing I have ever seem have been dimmers or relay banks that control 8 devices but you have to run the power wires from the device to these from the rooms. They have Ethernet connections on them. I saw them a lot for environments like Control4.
I do not know anything that uses the higher voltage mains wiring to send and receive these signals on top of the normal mains power.