How far can an arduino output go if I'll use a CAT6 cable to drive a solid-state relay?


How far can an arduino output go

There are no definitive answers for a question like this.
How far do you want to go and then we will see if it is on. Basically you have to light up an LED that requires 3.5V with a 5V signal so in theory you can afford a 1.5v drop along the wire. So work out the resistance of your cable and assume a current of 20mA and see a first guess.

Thanks Mike. I'm planning to close down a shutter around 300 meters away using arduino. I'll probably unreel a box of CAT6 and test.

That is a long way. If I were you I would drive a transistor with a pull up to 12V for that sort of distance.