In most North American electrical work, black (and sometimes red or blue) are hot conductors, white is neutral, and green or bare copper is ground. This color coding helps identify wires and reduces the risk of shocks or short circuits.
Color conventions can vary by country, circuit type, and age of installation. This article outlines the most common practices in the United States, notes key variations, and explains safety considerations so readers can understand what they’re dealing with—without attempting risky wiring tasks unless properly trained.
Common US color codes for standard residential wiring
Below is a quick reference of common color codes used in the United States for standard household wiring (120/240 volts), including the meaning of each conductor in typical 3- or 4-wire setups.
- Black — hot or live conductor in many circuits (often designated as L1).
- Red — second hot conductor on certain circuits or multi-wire branch circuits; frequently used for 240V appliances or a separate switched hot in a multi-wire arrangement.
- Blue — additional hot conductor in some configurations or for specific multi-wire or 3-phase setups; less common in standard residential wiring.
- White — neutral conductor, return path for current in 120V circuits.
- Green or bare copper — equipment grounding conductor, safety path to earth.
In modern installations, any conductor used as a hot must be re-identified if it is not a standard color, such as white repurposed as a hot. This helps prevent misidentification during maintenance or repairs and aligns with electrical code requirements.
Additional contexts and exceptions
Electrical color coding can vary depending on use case, age, and local code interpretations. The following notes describe common setups you might encounter.
Three-wire vs four-wire setups
Understanding the distinction between three-wire and four-wire feeders clarifies which colors represent hot, neutral, and ground across different appliances and installations.
- Three-wire with ground (older 120/240V circuits): black and red are hot, white is neutral, green/bare is ground.
- Four-wire (modern 240V appliances and feeders): black and red are hot, white remains neutral, green or bare is ground.
Older installations may use nonstandard colors or lack a dedicated ground. When in doubt, treat all unconfirmed conductors as potentially hazardous and consult a licensed electrician.
Three-phase and specialized wiring
In commercial or industrial settings with three-phase power, color conventions differ from typical residential wiring, though certain patterns remain common.
- L1, L2, L3 are commonly color-coded black, red, and blue (or brown, black, and grey in some regions) for the three live phases, with white as neutral in many systems and green/bare as ground.
- Low-voltage systems (thermostats, doorbells, data/control wiring) use different schemes not interchangeable with line-voltage wiring.
Always verify with local codes and use testing tools to confirm which conductor carries live current before touching any wiring.
Safety notes and when to call a pro
Color codes provide guidance, but they do not replace proper verification. Local codes may have specific requirements, and inaccuracies can lead to shock, fire, or equipment damage. If you’re not fully confident or the work involves high voltage, contact a licensed electrician.
Summary
Wiring color conventions primarily designate hot conductors as black (and sometimes red or blue), neutral as white, and ground as green or bare. Always verify with a tester and follow local electrical codes, especially for nonstandard or older installations. When in doubt, seek professional assistance to ensure safety and compliance.