Life span of arduino We are students of Pragati Engineering College -AP. We are currently working on Automatic Street Light  project selected in Smart India Hackathon 2017 under ministry of steel. For this project  We are using Arduino nano to control street lights in industries. Now we are requiring some general following  information about arduino nano. 

What is the life span of Arduino nano?
We need a micro-controller with on analog input pin to read analog voltage and four digital pins for output. The program that we are dumping include  serial communication with Java UI in PC. The program occupies 6750 bytes, 318 bytes for global variables and 1730 bytes for local variables. We would like to know which arduino board is best suitable for our project?
Atmel chips (the ones used in the Arduino) have been used in all sorts of industrial appilications way before Arduino came along. Same for other micro controllers like the still popular 8051.
What you want to focus on might be the enclosure, seal it against the outside.

Rather than using a (chunky) pre-manufactured Arduino board, you'll have to pick the right chip for your application and design a board around it. http://www.atmel.com/products/microcontrollers/avr/