Why distinguish the color of the wire?

Domestic standard

There are five different color wires in the general electrical box, which correspond to:

Yellow: L1 phase in three-phase circuit, ie phase A green: L2 phase in three-phase circuit, ie phase B red: L3 phase in three-phase circuit, ie phase C blue: working zero line N yellow green: protection Zero line PE

Three-phase electric energy meter wiring

Yellow-green protective ground wire

Who specified the color of the wire? In the national standard GB50258-96, when the wiring adopts multi-phase wires, the color of the phase line should be easy to distinguish, and the color of the phase line and the zero line (ie, the working zero line N) should be different. The protective earth wire (PE wire) should be insulated wire with yellow-green color and phase; the neutral wire (N wire) should be light blue insulated wire. GB/T6995.2-2008 specifies that the color of the L1/L2/L3 three-phase cable is yellow, green and red.

Why distinguish the color of the wire? National standards require different cables to be used in different colors, mainly to correctly distinguish the phase, neutral, and ground wires in the wires to prevent erroneous operations. In the general power construction unit, although there are strict operating specifications, in the real construction, there will always be people who are careless or mishandled, resulting in wiring errors and serious electrical accidents.

International standard

According to IEC: 60446: phase conductor color: black, brown, red, orange, yellow, green, purple, gray, white, pink, turquoise; neutral line recommended color: blue; ground line recommended color: yellow green Stripes (specified that this color cannot be used as other conductor colors)

Table. Color requirements for three-phase wires in some countries and regions of the world

Knowledge expansion: The neutral line is called the waterline in Taiwan; the phase line is called the fire line and the live line; in order to prevent the occurrence of short circuit, the color regulations of the neutral line and the ground line are hard requirements in the world.