Quick Guide to Electrical Wire Color Codes
Electrical wires differ in many details, including wire type, material, thickness, number of wires in the cable, insulation type and thickness, etc.
When building an electrical system, it is very important to follow the electrical installation diagram/schematics - in order to differentiate wires in electrical systems, wires come in different colors, and knowing which color goes where is of utmost importance.
Published: August 6, 2022.
Electric wire color code standards differ from country to country. As always, if unsure, hire a locally certified electrician (or company) to help You with wiring - better safe than sorry.
This article is about US wiring color codes.
DC (Direct Current) Power Color Codes
DC electricity is typically used in automotive, marine, and solar applications - many people have already seen jumper cables and know that Red is Positive and the Black is Negative.
Since most cars have their negative battery terminal post connected to the chassis, "negative" and "common ground" are the same.
However, in many DC applications, there are also dedicated wires for "common ground", which is usually White or Gray. Thus, in DC applications, the wire colors are as follows:
- Positive (not a common ground): Red,
- Negative (not a common ground): Black,
- Common Ground: White or Gray.
Again, White or Gray (common ground) wire is not used in jumper cables, 12V battery chargers, and similar applications since the negative terminal port of the battery is connected to the car's chassis and acts as common ground.
120/208/240 Volts AC (Alternate Current) Power Color Codes
120V AC, 208V AC, and 240V AC are typically found in residential objects and offices. Wire colors for these voltages are as follows:
- Phase 1: Black,
- Phase 2: Red,
- Phase 3: Blue,
- Neutral: White,
- Ground: Bare Wire, Green, or Green with Yellow Stripes.
277/480 Volts AC (Alternate Current) Power Color Codes
277V AC and 480V AC are typically used in industrial applications. Wire colors for these voltages are as follows:
- Phase 1: Brown,
- Phase 2: Orange,
- Phase 3: Yellow,
- Neutral: Gray,
- Ground: Bare Wire, Green, or Green with Yellow Stripes.
As one can see, phases of 120/208/240V AC wiring and 277/480V AC wiring do NOT share any color, except the "GROUND" - this is very important since just a quick look at the wiring tells the person enough information about used voltages and phases, significantly increasing the safety.
Note: Again, if unsure, hire a professional electrician (or company). Also, always check if the line voltage is present, if the electric breakers are in the Off position, etc. Better safe than sorry.
