Choice of wire color

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Article 3.1.9 of GB50258-96 "Code for Construction and Acceptance of Wiring Projects of 1KV and Below for Electrical Installation Projects": When multi-phase wires are used for wiring, the colors of the phase wires should be easy to distinguish. The colors of the phase wires and the neutral wire (i.e. neutral wire N - Editor's note) should be different. The color selection of wires in the same building or structure should be uniform. ； The protective ground wire (PE wire) should be a yellow-green insulated wire. ； The neutral line should use light blue (should be "blue" - editor's note) colored insulated wire. Violations of this provision are common in electrical wiring construction, and many people misunderstand this provision. Since this article is not explained in the specification description, the author will give some insights based on the situations encountered in actual projects. 1. The colors of phase wires should be yellow, green and red. Taking a residence with three phases into the building as an example, when the three-phase power supply is introduced into the three-phase watt-hour meter box, the phase wires should be yellow, green, and red. ； When a single-phase power supply is introduced into a single-phase watt-hour meter box, the phase wires should be yellow, green, and red respectively. The color of the phase wire of the three-core sheathed wire introduced from the single-phase watt-hour meter box to the household distribution box does not need to be the same as the phase wire of the connected household line. Only when the user uses a three-phase watt-hour meter box, the color of the box wires introduced from the three-phase watt-hour meter box to the household distribution box should be consistent with the phase wires entering the three-phase watt-hour meter box. The box wires entering the household distribution box in rooms 2 to 4 can be any one of yellow, green, or red, because GB50258-96 only stipulates that when multi-phase wires are used for wiring, the color of the phase wires must be easy to distinguish. For example, when a user in room 2 experiences a power outage, the incoming wire of the single-phase electricity meter in room 2 is red. You only need to use a test pen to check whether the red phase wire entering the building has power, and you can determine the fault. The residential design regulations stipulate that the cross-section of the wires from the watt-hour meter box to the distribution box of each household shall not be less than 10mm2. If the color of the phase wire from the household distribution box to the single-phase watt-hour meter box is the same color as the incoming wire of the single-phase watt-hour meter box, then you need to purchase 10mm2 sheathed wires in three colors. , will inevitably increase construction investment. If constructed according to the attached picture, you only need to purchase a 10mm2 three-core sheathed wire, one of which is a light blue neutral wire, one is a yellow and green two-color PE wire, and the third is any one of yellow, green, and red color phase wires. 2. The neutral wire color specification stipulates that the neutral wire should be light blue insulated wire. “"Appropriate" means: Light blue should be used first when conditions permit. some * * The neutral wire should be white. If the owner of the building requires white as the neutral wire, then all neutral wires in the building should be white. If the color of the neutral line is dark blue, then the color of the phase line should not be green, because under dim light, there is not much difference between dark blue and green. At this time, when the color of the phase line refers to single-phase power supply, red or yellow should be used. 3. The color specification of the protective ground wire stipulates that insulated wires of yellow and green colors should be used. “"Should" means must. Under normal circumstances, yellow and green insulated wires must be used. 4. When ordering cables or sheathed wires, you must indicate the color of the wires. In actual projects, it is often found that the colors of the wires in cables or sheathed wires do not meet the requirements. Some projects use three-phase lighting cables. The three phase wires are of the same color. ； Some projects use single-phase three-core lighting cables with yellow, green and red wires. This is not allowed by the specification. In addition, the remedy of wrapping ribbon on the wire should not be used. Therefore, when ordering cables or sheathed wires in the project, in addition to the model number, the cross section and color of the wire should also be indicated.