Understanding Electrical Outlet Wire Colors

Understanding your home’s electrical outlet wire colors is just as important in knowing how the basic circuit types work. General knowledge on wire colors will come in the handy during minor electrical emergencies such as changing an overhead light fixture, replacing a wall light, or installing new bulbs, lamps, and switches. Wires are color-coded to avoid wiring errors that may lead to the accidents and electrical inconvenience to household, the whole block, or in some cases the town.

Black Wires

Black wires are specifically used for the hot wires and voltage transmissions. Most of these wires are utilized as switch legs and may feed an outlet as well. You should not use these wires for a ground or neutral connection.

Red Wires

Red wires are second to the black wires when used as hot wires and switch legs for 220-volt installations. Aside from using it for the neutral connections, red wires can be used in three-way switch configurations.

Yellow and Blue Wires

These wires usually come in the pairs and pulled in conduits. They are used as hot wires and control electrical items like lights, switched outlets, and fans. Blue wires are generally used in three-way and four-way switch applications by travellers. On the other hand, yellow wires are used as switch legs.

Copper and Green Wires

Copper and green wires are used for grounding purposes only. They are specifically made for grounding electrical items and should be attached to appliance connections and junction boxes.

White Wires

Generally, wires in white do not follow certain rules like other colours. It can be sometimes used as a hot wire in a two-conductor cable or can be sometimes used for outlet connection. It can either also run a three-way switch application or be used as a switch leg for lighting. To avoid confusion on determining your white wire’s function, mark the wire’s end with red or black electrical tape.

Some countries have their own standard colour codes too. For jurisdictions without standard rules for wire colours, local custom and common practices of electrical inspectors are usually followed.

United States

For both AC and DC connections, the United States National Electrical Code states that white or gray wires should be used as grounded neutral conductors. Copper, green, and yellow wires should be used for protective ground. It is also common practice among local inspectors to use black for the first hot wire and use red for the second live or active wire.


The Canadian Electrical Code mandates green, yellow, or green wires with yellow stripes to be used for protective ground, and white wire is considered neutral. Black wires are for single live wires, red for second active wires, and blue for three-phase active lines.


Europe’s International Electrotechnical Commission Code states that green-yellow wires are protective ground wires. Brown or black wires should be used for hot and live wires. For neutral ground, blue wire should be used.

General Rule

A good rule of thumb is to always connect wires of the same colour. Also, before doing anything with wiring, always power down your main switch and use insulated tools as precautionary measures against injury.