On the relay side, this is a solved problem. Have a look at devices like the Shelly pro 4pm.
On the sensor side, there are a few very nice esp32 based boards. Have a look at the https://www.olimex.com/Products/IoT/ESP32/ESP32-POE-ISO/ and friends. These kind of things are fairly cheap and will handle most sensors really well. They're also perfectly supported by esphome.
I'm fiddling with a setup somewhat like what you describe at our countryside cottage. Star topology for literally everything into the technical room: 230v power, proper cat6 for the high speed data network, and cat5e for sensors.
I tried to keep the wiring super standard. All sensor cables get terminated centrally in a patch panel, ethernet style. On the sensor side, I break out the wires I want using simple couplers.
I don't do PoE up to the sensor. I haven't found cheap super compact PoE devices . That's not a problem though. With some multiplexing, an ESP32 can handle a surprising number of sensors both at the data and the power budget level. So I use a few PoE powered ESP32's in the central network rack, and I power my sensors through those.
On the sensor side, there are a few very nice esp32 based boards. Have a look at the https://www.olimex.com/Products/IoT/ESP32/ESP32-POE-ISO/ and friends. These kind of things are fairly cheap and will handle most sensors really well. They're also perfectly supported by esphome.
I'm fiddling with a setup somewhat like what you describe at our countryside cottage. Star topology for literally everything into the technical room: 230v power, proper cat6 for the high speed data network, and cat5e for sensors.
I tried to keep the wiring super standard. All sensor cables get terminated centrally in a patch panel, ethernet style. On the sensor side, I break out the wires I want using simple couplers.
I don't do PoE up to the sensor. I haven't found cheap super compact PoE devices . That's not a problem though. With some multiplexing, an ESP32 can handle a surprising number of sensors both at the data and the power budget level. So I use a few PoE powered ESP32's in the central network rack, and I power my sensors through those.