Color code for lines in electronic circuits?

Posted by: @wolfgangw

Maybe there is no such thing. Then I would have to create my own "norm"

Yes, that's the current state of affairs.   In fact commercially different companies and industries often have their own color code systems.   I used to do wiring for the USA military and they used green for ground.  Black is actually a live hot wire.

But as a hobbyist I tend to use black for ground too.  Although black is also hot on the AC house current in the USA.   Having worked on military projects I also tend to continue to use green for grounds as well.

The colors of all other signals is entirely open to your choice. 

Having said the above, there are standards that can be found.   Various auto manufactures often have color codes they use on their cars.  You could adopt one of those.  Although different auto manufactures tend to use different color codes. 

Here's a web page that can give you a lot of ideas for various color-coding conventions:

Electrical Color Code

If you are building a project with a lot of wiring you would do well to create your own color code system in advance.  That will make troubleshooting and assembly much easier as you move forward with the project. 

@robo-pi

Thanks James for that.
I already thought so. And I will follow to your suggetion.