For 12V Wiring on DC Circuits, Red Is Positive, Black Is Negative but What Is Yellow?

Question:

Hi Jeff. In your segment about battery cables, you said one of the reasons not to use welding cables was because all of the cables would be black, as opposed to black and red. Black and red being easier to differentiate negative and positive. That being the case, why are 12 volt dc circuits always wired with all red positive and all black, or, now yellow, for negative, as opposed to different colours for dc distribution, and black for negative, like those used in automotive and motorcycle wiring harnesses?  Thanks - Rob

Answer:

Good question, unfortunately don’t know how the standards came to be like that.  To avoid confusion, use yellow as DC negative cabling color. - Jeff