Depending on what you are working on, red and black have different meanings. I have come across this a bit in my life and want to take note of it, finally.
Financials
Black = Profit
Red = Loss
Electronics
Black = Ground
Red = Volts
Electrical
Black = Live
White = Neutral
Green = Ground
Coming from a knowledge base in electronics, the electrical color-coding is completely confusing. Came across an article from Angie’s List with more details.