What Color is Wire for Hot, Neutral, and Ground?

Wire color coding is a standardized visual system that identifies the electrical function and voltage level of a conductor to prevent shock and ensure correct circuit connections. When a DIYer or electrician asks "what color is wire" for a specific terminal, they are really asking about the National Electrical Code (NEC) mandates that keep 120V and 240V systems from becoming lethal hazards. While the copper inside the insulation behaves identically regardless of the jacket color, the outer coloring dictates how the circuit must be treated during installation, inspection, and troubleshooting.

The Standard US AC Wire Color Code Chart

For residential and light commercial alternating current (AC) systems in the United States, the NEC strictly defines which colors can be used for grounded (neutral) and grounding conductors, while leaving ungrounded (hot) conductors more flexible. Below is the definitive reference for standard 120V/240V split-phase systems.

Source: NFPA 70: National Electrical Code (NEC)

What Wire Color Actually Changes in a Real Circuit

From a pure physics standpoint, wire color changes absolutely nothing about the circuit's operation. Electrons do not care if the insulation is black, white, or pink. A 12 AWG copper wire has the exact same ampacity (20A at the 60°C column for NM-B cable) and resistance regardless of its jacket color.

What the color does change is the safety protocol and troubleshooting logic. The insulation color acts as a critical communication layer between the installer, the inspector, and the next person who opens that junction box five years later.

If you use a white wire as a hot leg without properly re-identifying it (e.g., wrapping black or red electrical tape around both ends per NEC 200.7), you create a lethal trap. The next person to work on that panel might grab the white wire bare-handed, assuming it is a dead neutral, only to receive a 120V shock. Conversely, the NEC strictly forbids re-identifying a colored wire (like black) to serve as a neutral. You can mark a white wire to be hot, but you can never mark a black wire to be neutral. This one-way rule ensures that a neutral wire is always reliably identifiable.

Where You Meet This in Practice: Wiring a 240V Dryer

To see how these colors interact in a real installation, let's look at wiring a standard 30A, 240V electric dryer using 10/3 NM-B cable. This cable contains four conductors: Black, Red, White, and Bare Copper.

1. Black (Hot L1): Connects to the first 30A breaker pole. Provides 120V relative to ground.
2. Red (Hot L2): Connects to the second 30A breaker pole. Provides 120V relative to ground, but 240V across the Black and Red wires.
3. White (Neutral): Connects to the neutral bus bar and the dryer's silver terminal.
4. Bare (Ground): Connects to the ground bus bar and the dryer's chassis grounding screw.

The Numeric Reality: Inside the dryer, the heavy heating element runs on 240V (Black to Red) and draws roughly 22 Amps. However, the dryer's control board, timer, and interior light run on 120V (Black to White) and draw only about 3 Amps.

Because the 240V load is perfectly balanced across L1 and L2, the white neutral wire only carries the 3A unbalanced return current for the electronics. The bare ground wire carries exactly 0A during normal operation.

Common Confusions: Switch Loops and DC vs. AC

When asking "what color is wire," people frequently confuse residential AC standards with other electrical environments or outdated code practices. Here are the two most common traps that cause DIYers to miswire circuits.

1. The "White Hot" Switch Loop

In older homes (wired before the 2011 NEC update), electricians commonly used 2-wire cable (Black and White) to run power from a ceiling light down to a wall switch. The black wire carried constant hot down to the switch, and the white wire carried the switched hot back up to the light.

If you open an old switch box and see a white wire connected to a switch terminal, it is not a neutral. It is a hot wire. Modern NEC (404.2) requires that a neutral be present in every switch box for smart switches, and mandates that the switched hot leg be a colored wire (like red or black), but you will still encounter legacy "white hots" in millions of older homes. Always test with a multimeter.

2. DC Battery Systems vs. AC Mains

If you are wiring a solar battery bank, an off-grid inverter, or automotive accessories, the color codes flip entirely. In direct current (DC) systems, Red is Positive (+) and Black is Negative (-).

A classic and dangerous mistake occurs when a hobbyist wires a 12V DC battery bank to a DC-to-AC inverter using standard AC assumptions. If you connect a black wire to the positive DC terminal because you are used to black being "hot" in AC, you will instantly short-circuit the system if the other end touches a grounded chassis, potentially causing a battery fire. Always verify whether you are working in an AC or DC environment before selecting your wire colors.