Wire color: The neutral wire is blue, and the color of the phase wire (A phase is yellow, B phase is green, and C phase is red) should meet the standard. The wiring color codes are the standard safety language of electricity. They make it easy to identify immediately which wires are live, neutral, or grounded (avoiding costly mistakes and hazardous accidents). Please refer to local regulations. Wiring Color Codes in Europe (IEC) for AC Supply Wiring Color Codes in Europe (IEC) for DC Supply Is this faq. Sometimes wires are marked with black or red tape to indicate they are “hot or “live”, meaning they carry electricity. If you have ever opened an outlet box or light fixture and seen a bundle of different colored wires, you are not alone.