I plan to run about 4-5 arduino pro micro in my backyard to handle controlling of solenoid valves for garden watering based on measurements of soil (so we keep it well watered).
My question regards the supply voltage, I wish to use cat 6 over maybe a 20m run in total to supply both power and RS485 networking over the twisted pairs.
Based on previous answers regarding cat6 I know the amperage should be fine assuming all arduino even run full without sleep around 45mA that's some 250mA.
The solenoid valve says 8w at 12v which is 0.6A, assuming the current is required to keep it open (not closed - is this correct?) which I'd hope so otherwise loss of power would cause it to open.
I guess I'd need to run 12v anyway, should I run 12v and 5v down the pairs? If I run just 12v I need a linear voltage regulator, which get quite hot does that mean they are inefficient? If I run 5v as well, how well does 5v perform over that distance due to voltage drop on cat6 pairs?