Maximum distance from Arduino ports to sensors

Other Hardware Sensors
5

I would suggest scenario "A" with the following details:

  • use twisted wire. Could use Cat 5 and ground all the other wires at the arduino.
  • Add an opto isolator at the Arduino end.
  • heavily filter the input at the board.
  • use a lower resistance for R1, like 500 ohms.
  • put the switch to switch to ground not high

The opto may not be too useful if you must power the switch from the same Vin.