Electrical Wire Color Code: US Hot, Neutral and Ground
Chameera Sampath · 10/17/2026
US electrical wire color code under the NEC: neutral and ground rules, black-red-blue and brown-orange-yellow conventions, jacket colors, DC and IEC colors.
The electrical wire color code in the United States identifies the purpose of each conductor in a circuit. The National Electrical Code (NEC) fixes three things: the grounded conductor (neutral) is white or gray, the equipment grounding conductor is green, green with yellow stripes, or bare, and those colors may not be used for hot conductors. Within those rules, the familiar black, red and blue for hot conductors are industry convention rather than code requirements.
Quick answer. On a standard US 120/240 V or 208Y/120 V system: black, red and blue are hot, white is neutral, and green or bare is ground. On a 480Y/277 V system: brown, orange and yellow are hot and gray is neutral. Color is a guide, not proof — every conductor should be tested before work.
What the NEC requires
| Conductor | Required identification | NEC reference |
|---|---|---|
| Grounded conductor (neutral) | White or gray, or three continuous white or gray stripes on another color | 200.6 |
| Equipment grounding conductor | Bare, green, or green with one or more yellow stripes | 250.119 |
| Ungrounded conductor (hot) | Any color other than white, gray or green | 200.7, 250.119 |
| High leg of a 4-wire delta system | Orange, or marked orange | 110.15 |
Where more than one voltage system is present in a building, the NEC also requires the identification method for each system to be documented and posted, which is where the black-red-blue and brown-orange-yellow conventions come from.
Common color schemes
| System | Hot conductors | Neutral | Ground |
|---|---|---|---|
| 120 V, single phase | Black (red on a second circuit) | White | Green or bare |
| 120/240 V, single phase | Black and red | White | Green or bare |
| 208Y/120 V, three phase | Black, red, blue | White | Green or bare |
| 480Y/277 V, three phase | Brown, orange, yellow | Gray | Green or bare |
| 240 V high-leg delta | Black, orange (high leg), blue | White | Green or bare |
The pairing of white neutral with 120 V systems and gray neutral with 277 V systems lets an electrician tell at a glance which system a neutral belongs to when both run in the same building.
Ground wire color
The ground wire, properly the equipment grounding conductor, is green, green with yellow stripes, or bare copper. In nonmetallic-sheathed cable (Romex and similar) it is normally bare. A green conductor must never be used as a hot or a neutral.
Neutral wire color
The neutral is white on 120 V-based systems and gray on 277 V-based systems. Conductors 4 AWG and larger, which are often available only in black, may be identified as neutral by white or gray marking such as tape at each termination.
Re-identified conductors
The NEC permits some exceptions in which a white conductor is used as a hot. The most common is a switch loop in cable, where the white conductor carries the hot to the switch. In those cases the white conductor must be re-marked at each end, usually with black or red tape, so that it is not mistaken for a neutral. Unmarked white conductors in a switch box of an older house are a frequent source of confusion and of shocks.
Switch and three-way wiring
On three-way switch circuits, the two conductors running between the switches are called travelers. Red and black are common, but the code does not assign travelers a color, and the cable colors available often decide it. Testing, not color, establishes which conductor is the common.
Cable jacket colors
Manufacturers of nonmetallic-sheathed building cable color the outer jacket by conductor size, which helps match cable to breaker:
| Jacket color | Conductor size | Common circuit |
|---|---|---|
| White | 14 AWG | 15 A |
| Yellow | 12 AWG | 20 A |
| Orange | 10 AWG | 30 A |
| Black | 8 AWG and 6 AWG | 40 A to 60 A |
| Gray | Underground feeder (UF) cable | Varies |
Jacket color is a manufacturer convention, not a code rule. The circuit rating still depends on the conductor's ampacity and terminal temperature; the ampacity calculator and breaker size calculator cover the check, and the wire size calculator adds voltage drop. The pages for each breaker rating, such as 20 amp, 30 amp and 50 amp wire size, give the minimum copper and aluminum sizes, and the AWG wire gauge chart gives each gauge's diameter and resistance.
DC circuits
On direct-current systems such as solar arrays and battery banks, red is commonly used for positive and black for negative. Because black means hot on AC systems, DC conductors should be clearly marked by polarity at terminations, and the NEC adds polarity-marking requirements for DC branch circuits above certain voltages. Solar conductors are sized by voltage drop as well as ampacity; see the solar wire size calculator.
US and international colors
Visitors working on equipment from other countries meet a different scheme. Under the harmonized IEC scheme used across Europe and the United Kingdom:
| Function | United States (convention) | IEC / UK / Europe |
|---|---|---|
| Phase or hot | Black, red, blue (208/120 V) | Brown, black, gray |
| Neutral | White or gray | Blue |
| Protective earth or ground | Green, green-yellow, or bare | Green-yellow |
Blue means hot in the United States and neutral in IEC countries. Equipment wired to one scheme and installed under the other is a recognized hazard.
Why color is never enough
Color shows how a conductor was intended to be used, not what it is doing now. Previous owners, remodels and repairs leave conductors re-purposed, unmarked or miswired. Before touching any conductor, it should be tested with a voltage tester rated for the circuit, and the circuit verified de-energized at the panel.
Frequently asked questions
What color is the ground wire? Green, green with yellow stripes, or bare copper.
What color is the neutral wire? White on 120/240 V and 208Y/120 V systems; gray on 480Y/277 V systems.
What do the red and black wires mean? Both are hot conductors. On 240 V circuits they are the two hot legs; on 120 V circuits red is often a second hot, a switch leg or a traveler.
What does a blue wire mean? In the United States, a hot conductor, usually the third phase of a 208Y/120 V system. In IEC countries, blue is neutral.
Can a white wire be hot? Yes, in permitted cases such as a switch loop, provided it is re-marked with tape or paint at every termination to show it is not a neutral.
Scope
This guide describes conductor identification in the United States under the National Electrical Code, with the common industry conventions noted as such. Local amendments may add requirements, and the posted identification scheme in a building takes precedence over general convention.
Written by Chameera Sampath. Not yet reviewed by a licensed electrician — see the methodology page. To report an error, use the contact page.