Relay control using ethernet cable

Hi,

I need to control a light at a distance of 10-20 m There is an Ethernet cable already installed inside the house In fact there are two cables so I can use all 8 wires of one cable for the task if needed Can I use it to connect Arduino to a remote relay that will switch a lamp on and off? Relays are controlled by 5 volts, will it work over the 10-20 meter distance using Ethernet cable? There will be some voltage drop

I guess feeding 12v power current for LED lamp through ethernet cable is even worse

If you use 2pairs tied together for supply and the others for return, you will have no problems turning on the relay with 5v.

Depending on the power required, you may even be able to turn on the LED. As it will be driven by constant current, you can adjust the voltage to give the current required.

Weedpharma

12V power is even better! Think about long-distance power transmission towers. They're really high voltage (in addition to being high off the ground.) The high voltage reduces current losses in the long lines.