What Are Electric Cable Colours？

The colours of the wire is very diverse, mainly black, white, green, red, blue, orange, brown and gray. In the United States, the ground line is green, yellow-green striped, or bare, the neutral line should be white or gray, and the electrical line may be black, red, blue, yellow, orange, or yellow, depending on the voltage.

These colours standards are American, other country codes are different (Canada's are very similar to the United States). For example, Australia and New Zealand have the same color ground wires as the United States, and their neutral wires are blue or black. Moreover, live wires can be any color other than ground wires and neutral wires. Red and brown are the recommended colors for single-phase lines, and red, white, and blue are the recommended colors for wires with multiphase flow.

The UK has recently (2004) changed its compliance with the International Electrotechnical Commission (EC) system. Their ground line colour (yellow and green stripes) remained the same, and their neutral line color changed from the original black to blue. Similarly, single-phase wires that used to be red have turned brown. In addition to this, the markings and coloring of the polyphase lines in the UK were also changed: L1 from red to brown, L2 from yellow to black, and L3 from blue to grey.

Extended information:
Residential electricity use in the United States began without systematic color coding, or even a set of standards for proper use. In 1879, shortly after Edison introduced the first electric light, the insurance industry began issuing safety guidelines. The first set of formal guidelines appeared in 1881, covering addressing capacity, insulation, and installation. But there is no classification of wire colours.