Standard Wiring Color Codes for AC & DC Circuits – IEC, US, UK & Canada

Accurate wiring color identification is essential for safe and compliant electrical installations. Depending on the region and the type of system—AC or DC—different standards apply. Below is a concise, authoritative reference that follows the latest IEC guidelines, U.S. NEC, and local codes.

IEC (International Electrotechnical Commission) – AC Wiring Color Codes (Most of Europe)

Function	Label	Color (IEC)	Color (Legacy IEC)
Protective earth	PE	Green‑Yellow	Green‑Yellow
Neutral	N	Blue	Blue
Line, single phase	L	Brown	Brown or Black
Line, 3‑phase – L1	L1	Brown	Brown or Black
Line, 3‑phase – L2	L2	Black	Brown or Black
Line, 3‑phase – L3	L3	Grey	Brown or Black

Legacy codes did not guarantee proper phase rotation; the modern IEC system does. The protective ground is green with a yellow stripe.

Click to expand infographic

United Kingdom – AC Wiring Color Codes

Function	Label	Color (IEC)	Old UK Color
Protective earth	PE	Green‑Yellow	Green‑Yellow
Neutral	N	Blue	Black
Line, single phase	L	Brown	Red
Line, 3‑phase – L1	L1	Brown	Red
Line, 3‑phase – L2	L2	Black	Yellow
Line, 3‑phase – L3	L3	Grey	Blue

United States – AC Wiring Color Codes

The U.S. National Electrical Code (NEC) mandates white or grey for neutral and a bare, green, or green‑yellow stripe for protective ground. All other colors may be used for hots, but local practice is consistent:

Function	Label	Common Color	Alternative Color
Protective ground	PG	Bare, green, or green‑yellow	Green
Neutral	N	White	Grey
Line, single phase	L	Black or Red (2nd hot)
Line, 3‑phase – L1	L1	Black	Brown
Line, 3‑phase – L2	L2	Red	Orange
Line, 3‑phase – L3	L3	Blue	Yellow

Canada – AC Wiring Color Codes

Canadian Electrical Code (CEC) follows a similar pattern to the U.S., with specific color conventions for single‑phase and three‑phase systems.

Function	Label	Color (Common)
Protective ground	PG	Green or green‑yellow
Neutral	N	White
Line, single phase	L	Black or Red (2nd hot)
Line, 3‑phase – L1	L1	Red
Line, 3‑phase – L2	L2	Black
Line, 3‑phase – L3	L3	Blue

IEC – DC Wiring Color Codes

DC installations, such as solar arrays and data centers, adopt the same color logic as AC for safety and interoperability. Below is the IEC standard for DC systems, adapted from Cook’s Table 2.

Function	Label	Color
Protective earth	PE	Green‑Yellow
2‑wire unearthed DC system
Positive	L+	Brown
Negative	L-	Grey
2‑wire earthed DC system
Positive (negative‑earthed)	L+	Brown
Negative (negative‑earthed)	M	Blue
Positive (positive‑earthed)	M	Blue
Negative (positive‑earthed)	L-	Grey
3‑wire earthed DC system
Positive	L+	Brown
Mid‑wire	M	Blue
Negative	L-	Grey

United States – Recommended DC Wiring Color Codes

NEC requires grounded neutrals to be white or grey, and protective grounds to be bare, green, or green‑yellow. Hot conductors may be any other color, but local inspectors typically advise black for the first hot and red for the second. The table below follows Wiles’ recommendations. Ungrounded systems are discouraged for safety.

Function	Label	Color
Protective ground	PG	Bare, green, or green‑yellow
2‑wire ungrounded DC system
Positive	L+	No recommendation (red)
Negative	L-	No recommendation (black)
2‑wire grounded DC system
Positive (negative‑grounded)	L+	Red
Negative (negative‑grounded)	N	White
Positive (positive‑grounded)	N	White
Negative (positive‑grounded)	L-	Black
3‑wire grounded DC system
Positive	L+	Red
Mid‑wire (center tap)	N	White
Negative	L-	Black

For precise calculations of wire sizes and resistances, explore our Wire & Resistor Calculators in the Tool section.

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