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    Wire Colors: What the NEC Requires vs What Is Just Habit

    Neutral and ground colors are code. Hot colors are not, and most people think they are. Here is the line between them.

    REQUIRED by code

    Grounded (neutral), 6 AWG and smaller Continuous white or gray, or three continuous white/gray stripes. NEC 200.6(A)
    Grounded (neutral), larger than 6 AWG White/gray finish, three stripes, or distinctive white/gray marking at terminations. NEC 200.6(B)
    White and gray are reserved They may only identify the grounded conductor. NEC 200.7
    Equipment ground, 6 AWG and smaller Green, or green with yellow stripes, for its entire length. NEC 250.119
    Equipment ground, larger than 6 AWG May be re-identified green at every accessible point instead.

    NOT required, and this is the useful part

    • There is NO NEC rule setting the color of an ungrounded (hot) conductor. Black, red and blue on 120/208, and brown, orange and yellow on 277/480, are trade convention. Widespread, sensible, and not a code requirement.
    • What IS required: where a building has more than one voltage system, ungrounded conductors must be identified by system, the method must be used consistently, and it must be POSTED at each panelboard. NEC 210.5(C). The code cares that it is documented and consistent, not which color you picked.
    • So a panel with unconventional hot colors and a posted legend can be compliant, while a conventional one with no legend is not.

    The size threshold, stated plainly

    • Sources word it as 'larger than 6 AWG' or '4 AWG and larger'. These are the SAME boundary. Standard AWG runs 6, 4, 3, 2, so there is no size in between.
    Section numbers are the NEC's own. Which edition binds you is decided by your state, and adoption is uneven: states run several editions behind each other and some amend individual articles. Check the edition your jurisdiction has adopted before relying on a section number, and use the building codes checker on this site for your state's adopted NEC edition. This card is for spotting obvious wrongness, not for doing the electrical work.

    Sources: nfpa.org

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