<P> The United States National Electrical Code requires a bare copper, or green or green / yellow insulated protective conductor, a white or grey neutral, with any other color used for single phase . The NEC also requires the "high leg" conductor of a high - leg or "bastard - leg" system to have orange insulation . </P> <P> The introduction of the NEC clearly states that it is not intended to be a design manual, and therefore, creating a color code for ungrounded or "hot" conductors falls outside the scope and purpose of the NEC . However, it is a common misconception that "hot" conductor color - coding is required by the Code . </P> <P> In the United States, color - coding of three - phase system conductors follows a de facto standard, wherein black, red, and blue are used for three - phase 120 / 208 - volt systems, and brown, orange, and yellow are used in 277 / 480 - volt systems . In buildings with multiple voltage systems, the grounded conductors (neutrals) of both systems are required to be identified and made distinguishable to avoid cross-system connections . Most often, 120 / 208 - volt systems use white insulation, while 277 / 480 - volt systems use gray insulation, although this particular color code is not currently an explicit requirement of the NEC . </P> <P> The United Kingdom requires the use of wire covered with green / yellow striped insulation, for safety earthing (grounding) connections . This growing international standard was adopted for its distinctive appearance, to reduce the likelihood of dangerous confusion of safety earthing (grounding) wires with other electrical functions, especially by persons affected by red - green colour blindness . </P>

In house hold wiring what is colour of earth wire
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