According to the national standard (GB681), in order to facilitate the identification of the roles and categories of various wires in the complete set of equipment, the color markings for each type of wire are clearly specified as follows:


1. Black - internal wiring of devices and equipment;

2. Brown - positive pole of DC circuit;

3. Red - the third phase of the AC three-phase circuit;

——The collector of a semiconductor transistor;

——The cathode of semiconductor diodes, rectifier diodes, and thyristors;

4. Yellow - the first phase of an AC three-phase circuit

——The base of a semiconductor transistor;

——The gate of thyristors and bidirectional thyristors;

5. Green - the second phase of the AC three-phase circuit;

6. Blue - the negative pole of the DC circuit;

——Emitter of semiconductor transistor;

——Anodes for semiconductor diodes, rectifier diodes, and thyristors;

7. Light blue - the neutral or neutral line of an AC three-phase circuit;

——Grounding intermediate line of DC circuit;

8. White - the main electrode of the bidirectional thyristor;

——Semiconductor circuits without specified colors;

9. Yellow green dual color - safety grounding wire;

10. Red and black parallel - an AC circuit connected by a pair of core wires or twisted pair wires.