What is the color code for 24 volt wire?

What is the color code for 24 volt wire?

There is no color code. You can use any color on low voltage. Look at a phone system, there are plenty of colors used. In HVAC, thermostat wiring is typically coded because of the code on the thermostat. With regular voltage the only restriction is that you can't use green as a conductor. The best thing to do is to number the wires. In auto wiring you need a schematic to follow wiring since there is no standard color code.