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Wiring Color Codes

Wiring for AC and DC power distribution branch circuits are color coded for identification of individual wires. In some jurisdictions all wire colors are specified in legal documents. In other jurisdictions, only a few conductor colors are so codified. In that case, local custom dictates the “optional” wire colors.

IEC, AC: Most of Europe abides by IEC (International Electrotechnical Commission) wiring color codes for AC branch circuits. These are listed in Table below. The older color codes in the table reflect the previous style which did not account for proper phase rotation. The protective ground wire (listed as green-yellow) is green with yellow stripe.

IEC (most of Europe) AC power circuit wiring color codes.

FunctionLabelColor, IECColor, Old IEC
Protective earthPEgreen-yellowgreen-yellow
Line, single phaseLbrownbrown or black
Line, 3-phaseL1brownbrown or black
Line, 3-phaseL2blackbrown or black
Line, 3-phaseL3greybrown or black

UK, AC: The United Kingdom now follows the IEC AC wiring color codes. Table below lists these along with the obsolete domestic color codes. For adding new colored wiring to existing old colored wiring see Cook. [PCk]

UK AC power circuit wiring color codes.

FunctionLabelColor, IECOld UK Color
Protective earthPEgreen-yellowgreen-yellow
Line, single phaseLbrownred
Line, 3-phaseL1brownred
Line, 3-phaseL2blackyellow
Line, 3-phaseL3greyblue

US, AC:The US National Electrical Code only mandates white (or grey) for the neutral power conductor and bare copper, green, or green with yellow stripe for the protective ground. In principle any other colors except these may be used for the power conductors. The colors adopted as local practice are shown in Table below. Black, red, and blue are used for 208 VAC three-phase; brown, orange and yellow are used for 480 VAC. Conductors larger than #6 AWG are only available in black and are color taped at the ends.

US AC power circuit wiring color codes.

FunctionLabelColor, CommonColor, Alternative
Protective groundPGbare, green, or green-yellowgreen
Line, single phaseLblack or red (2nd hot)
Line, 3-phaseL1blackbrown
Line, 3-phaseL2redorange
Line, 3-phaseL3blueyellow

Canada: Canadian wiring is governed by the CEC (Canadian Electric Code). See Table below. The protective ground is green or green with yellow stripe. The neutral is white, the hot (live or active) single phase wires are black , and red in the case of a second active. Three-phase lines are red, black, and blue.

FunctionLabelColor, Common
Protective groundPGgreen or green-yellow
Line, single phaseLblack or red (2nd hot)
Line, 3-phaseL1red
Line, 3-phaseL2black
Line, 3-phaseL3blue

IEC, DC: DC power installations, for example, solar power and computer data centers, use color coding which follows the AC standards. The IEC color standard for DC power cables is listed in Table below, adapted from Table 2, Cook. [PCk]

IEC DC power circuit wiring color codes.

Protective earthPEgreen-yellow
2-wire unearthed DC Power System
2-wire earthed DC Power System
Positive (of a negative earthed) circuitL+brown
Negative (of a negative earthed) circuitMblue
Positive (of a positive earthed) circuitMblue
Negative (of a positive earthed) circuitL-grey
3-wire earthed DC Power System

US DC power: The US National Electrical Code (for both AC and DC) mandates that the grounded neutral conductor of a power system be white or grey. The protective ground must be bare, green or green-yellow striped. Hot (active) wires may be any other colors except these. However, common practice (per local electrical inspectors) is for the first hot (live or active) wire to be black and the second hot to be red. The recommendations in Table below are by Wiles. [JWi] He makes no recommendation for ungrounded power system colors. Usage of the ungrounded system is discouraged for safety. However, red (+) and black (-) follows the coloring of the grounded systems in the table.

US recommended DC power circuit wiring color codes.

Protective groundPGbare, green, or green-yellow
2-wire ungrounded DC Power System
PositiveL+no recommendation (red)
NegativeL-no recommendation (black)
2-wire grounded DC Power System
Positive (of a negative grounded) circuitL+red
Negative (of a negative grounded) circuitNwhite
Positive (of a positive grounded) circuitNwhite
Negative (of a positive grounded) circuitL-black
3-wire grounded DC Power System
Mid-wire (center tap)Nwhite

Lessons In Electric Circuits copyright (C) 2000-2020 Tony R. Kuphaldt, under the terms and conditions of the CC BY License.

See the Design Science License (Appendix 3) for details regarding copying and distribution.

Revised July 25, 2007

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