Which color represents 400 volts in color coding?

• A. Yellow
• B. Blue
• C. Red
• D. Green

Answer: (C)

In a three-phase system, the voltage of 400 V refers to the line-to-line potential between the phase conductors. The phase wires are color-coded with distinct colors to show they’re all live and part of the same high-voltage system. In many common standards, the three phase conductors are colored red, yellow, and blue, while earth is green (and neutral is handled separately). Red is one of the phase colors used to identify a live conductor in a 400 V three-phase setup. So, when you see red in this color-coding scheme, it signals a 400 V live conductor, as opposed to neutral or earth.