Quick & Easy Guide to Electrical Wire Color Coding

Have you ever encountered a rainbow-colored jumble of electrical wires and not known what how to tell them apart? Electrical wires are color-coded according to purpose. Understanding the electrical wire color coding system and knowing the function of each wire is important to make sure you are using them appropriately and safely. Color code your wires properly to help guide anyone who later tries to make repairs on your electrical system.

Electrical wiring and voltage varies around the world, but here in America most homes are wired with 120/240V electrical service. Incoming 240V power is split onto two legs, which each conduct 120V hot-to-neutral power. Combining the two legs will provide 240V service, used to supply heavy loads for large appliances such as air conditioning compressors. Within the home, wires in the 120V circuits are color coded to indicate type and size, while the color of the insulation coating indicates function. Electrical wire color coding is designated by the National Electric Code (NEC).

Here’s a quick guide to electrical wire color coding.

De-Coding Electrical Wire Color Coding

Black Wires 

Wires with a black insulation coating are always used as hot wires, or ungrounded conductors. Hot wires are used to feed a switch or an outlet. Black wires should never be used for a neutral or ground connection.

Red Wires

Red wires are multipurpose. Like black wires, they can be used for as ungrounded conductors. They are also commonly used as the second wire in a 220-volt installation, as a switch leg, or in a circuit that requires an interconnection, such as a smoke detector.

Blue and Yellow Wires

Blue, yellow, and other colored wires can be used to differentiate the paths and destinations of different wires stemming from the same box. For example, if one black wire conducts power from a ceiling box down to three light switches, three different colors of wire may be used to identify the wires leading back to the ceiling box from each switch.

READ MORE: Winter Electrical Safety Tips

White Wire

White wires are used as grounded conductors or neutral wires. Though other wire colors (green and grey) can be used for commercial or outdoor wiring, only white wires should be used as grounded conductors in small residential branch circuits.

Green and Bare Copper Wires 

Wires with green insulation coating and non-insulated bare copper wires are used exclusively as equipment grounding conductors (EGC), otherwise known as grounding wires. When the electrical system is running smoothly, EGC wires actually lie dormant. However, if there’s a surge or a fault that could potentially damage appliances or cause a fire, power is re-directed and channeled through the underground EGC wiring. EGC wires are connected to switches, receptacles, and electrical boxes as a safety precaution.

You may never find yourself in the position of having to wire something or even decode the different colors of wiring in your home, but it’s still good to understand electrical wire color coding and be aware that each wire serves a specific function.

When you’re having electrical wiring trouble, it’s always safest to call in a professional. If you need electrical wiring service, present this coupon to your Bonfe electrician to receive $35 off any electrical repair.

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