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In electrical engineering, ground and neutral (earth and neutral) are circuit conductors used in alternating current (AC) electrical systems. The neutral conductor receives and returns alternating current to the supply during normal operation of the circuit; to limit the effects of leakage current from higher-voltage systems, the neutral ...
For power circuits, the color-coding uses the same colors as residential construction, and adds the additional wires used for three-phase systems. Black, Red and Blue are used for hot wires and White is used as the neutral wire in a 120/208 V circuit. Brown, Orange and Yellow are used as hot wires and gray is used as the neutral wire in a 277/ ...
Three-phase systems may have a fourth wire, common in low-voltage distribution. This is the neutral wire. The neutral allows three separate single-phase supplies to be provided at a constant voltage and is commonly used for supplying multiple single-phase loads. The connections are arranged so that, as far as possible in each group, equal power ...
Wiring regulations govern the application of split-phase circuits so that the shared neutral can be protected from excess current. A neutral wire can be shared only by two circuits fed from opposite lines of the supply system, using circuit breakers connected by a bar so that both trip simultaneously ([4] NEC 210.4); this prevents 120 V from ...
A somewhat similar system called "concentric wiring" was introduced in the United States around 1905. In this system, an insulated electrical wire was wrapped with copper tape which was then soldered, forming the grounded (return) conductor of the wiring system. The bare metal sheath, at earth potential, was considered safe to touch.
The international standard IEC 60446 Basic and safety principles for man-machine interface, marking and identification - Identification of equipment terminals, conductor terminations and conductors was a standard published by the International Electrotechnical Commission (IEC) that defined basic safety principles for identifying electrical conductors by colours or numerals, for example in ...
The color of a device neither identifies its voltage class nor power system. Because the colors are not specified by NEMA standards, the purpose of color-coding a receptacle may be set by the building owner, who may select brown, ivory, white, almond, grey, or black receptacles in the 5-15 configuration to blend with the decor of a room.
Systems incorporating color-coding include: In electricity: 25-pair color code – telecommunications wiring; Audio and video interfaces and connectors § Color codes; Optical fibers § Color codes; Electrical wiring – AC power phase, neutral, and grounding wires; Electronic color code AKA resistor or EIA color code (today – IEC 60062:2016)