In our daily lives, wires are everywhere. If you pay attention, you'll notice they come in a variety of colors. I believe many people don't quite understand the significance of wire colors. Our homes typically draw electricity from a three-phase power grid, and many people don't know what color each wire represents.
Common wire colors include black, white, green, red, blue, yellow-green, brown, and gray. The color of the insulation on a wire generally indicates its function. Therefore, during routine maintenance and inspection of electrical equipment, in addition to turning off the main switch, we also need to identify the specific wire we encounter.
First, what do the different colors represent?
1. Three-phase five-wire wiring: This system consists of three phases (A, B, and C) and one neutral (northeast). The national standard for three-phase five-wire wiring is: blue (green) for A and B, red for C, brown for N, and yellow-green or black for PE. Generally speaking, the three-phase wires are yellow, green, and red, representing A, B, and C, respectively. Blue represents the neutral wire, and yellow-green represents the ground wire. When connecting, the yellow, green, and red wires connect to the neutral wire, and the yellow-green wire connects to the polyethylene protective conductor or the equipment housing (which is already connected to the grounding network). Sometimes, when the colors of the four wires are not clearly distinguishable, three wires of equal cross-section are designated as the live wire, and the smaller wire is designated as the neutral wire. In a 220-volt single-phase power supply, there is one live wire and one neutral wire. In practice, safety is paramount, and red is designated as the live wire, blue as the neutral wire, and yellow or yellow-white as the ground wire. Phase wires are typically yellow, green, and red, while the protective neutral wire (PEN) is black. The protective neutral wire (PE) is a two-color yellow-green wire and must not be used as a phase wire under any circumstances.
Speaker Cable
Speaker Cable
According to the "Construction Specifications for Residential Decoration and Renovation Projects" (GB) 50327-2001, Article 16.1.4: "When wiring, the phase and neutral wires should be different colors; the phase wire (L) within the same residence should have the same color. The neutral wire (N) should be blue, and the protective conductor (PE) must be a yellow-green two-color wire. The protective conductor (PE), also known as the grounding conductor, must (mandatory) be a yellow-green two-color wire. The neutral wire should be blue (not mandatory; blue should be used where conditions permit). Three-phase wires should be red, yellow, and green, not blue."
2. After voltage reduction at the substation, the neutral voltage of a typical residential power supply line is 380 volts, and the voltage between the phase wire and the ground or neutral wire (i.e., the phase voltage) is 220 volts.
The common mains power supply in residential areas is a three-phase, four-wire system. Our single-phase system uses one phase plus the neutral wire. The phase wire (hot wire) of 220-volt AC power is red or brown, as these two colors are hot and eye-catching. The neutral wire can be blue or green, and the ground wire is black or yellow-green. Commonly used colors are red for the phase wire, blue for the neutral wire, and black or yellow-green for the ground wire.
3. DC power cord: Red indicates positive, black for negative.
Multi-strand power cords offer flexible layout. RVV22.5 and RVV21.5 wires are commonly used. These wires represent cores of 2.5 square millimeters and 1.5 square millimeters, respectively. They can carry currents of up to 10A and 6A, which are sufficient for small appliances.
This concludes our discussion of what wire colors mean. I hope this helps.
