We worked with some occasionally high voltage equipment that required handling from time to time. We built the stoplight as a way of tracking the voltage and staying out of the way when the system was hot.
Perhaps the best we had was to idea have all three lights flash when there was no signal at all. That way you're not deceived by disconnected cables.
I suppose this project owes big debt of inspiration to mkanoap's network stoplight though this project differs in the simplicity of the components used in the assembly. Thanks to the friendly components of Mouser electronics Arduino Tinker kit, it was built with almost no soldering.
Bill of Materials:
Replacement lamps (optional, if you want to get rid of the blinking, we used pricey LED ones so we didn't have heat issues)
TinkerKit Sensor Shield
TinkerKit Relay Module x 3 (one for each light)
DC Power Supply (we used a RS-15-15 which we dialed down to 12V)
Some small screws for mounting components (optional)
A couple resistors (depends on application)