you are right, it is better to provide more details about my actual setup in order to have suggestions.
At the moment I have a Claber unit that is positioned outside my home, more or less at 15 meters from the building, and that unit receives just one cable with 220 power (less than 1 centimeter of diameter).
This unit is located inside an ip65 container, and is linked to 5 valves that are positioned at 1 meter from the unit, using original cables bundled with valves.
Due to the fact that I’m moving to OpenSprinkler, I have some doubts that the external positioning is safe (especially for robbers), so I would like to install the new OS unit in my house, bringing only the connection to the external valves.
Having a lot of connections from the building to valves, around 15 + 1 meters, requires too much space in the grounded container of cables, so I have thought that replacing the existing power cable with an UTP cable (having more or less the same diameter) will be easily managed, and should allow me to control up to 7 sprinklers (if working of course).