US Wire Color Codes

Grounded and grounding conductors

Two conductors have colors the code actually locks down. The grounded conductor, what most people call the neutral, must be white or gray. The equipment grounding conductor must be green, green with a yellow stripe, or bare copper.

These two are non negotiable. You cannot use white or green for a hot conductor at standard sizes, and you cannot use them for anything but their intended job.

Hot conductor conventions

Hot, or ungrounded, conductors do not have strict mandated colors at common sizes, but the trade follows strong conventions so everyone can read a panel at a glance.

• 120/240 volt single phase: black and red for the hots.
• 120/208 volt three phase: black, red, and blue.
• 277/480 volt three phase: brown, orange, and yellow.

Follow the local convention even where it is not strictly required. The next electrician who opens that box is trusting your colors.

The high leg and re-identifying

On a high leg delta system, the conductor with the higher voltage to ground must be marked orange. It matters because putting 120 volt equipment on that leg gives it roughly 208 volts and destroys it.

When you reuse a white conductor as a hot, for example in a switch loop, you must re-identify it with colored tape or marking so nobody mistakes it for a neutral. Wrap it clearly at every accessible point.

Consistency is the compliance

The code cares most that your color scheme is consistent throughout a building and documented where required. An inspector will fail a job where phase colors flip from panel to panel because that is a real hazard for the next worker.

Pick your scheme, post it, and stick to it on every circuit. Discipline here prevents shocks, ruined equipment, and callbacks.