Electrical Wiring Colors: Wire Color Code Standards by Country
Understanding electrical wire color codes is essential for safe wiring work. Whether you are working on a home electrical project, troubleshooting an industrial panel, or wiring a circuit in another country, knowing what each wire color means prevents dangerous mistakes and ensures code compliance.
This guide covers wire color standards for the United States (NEC), Canada (CEC), United Kingdom (BS 7671), European Union (IEC 60446), Australia/New Zealand, and India. We also cover low-voltage DC wiring colors for automotive, solar, and electronics applications.
Why Wire Colors Matter
Wire colors serve a critical safety function. They tell electricians, inspectors, and DIYers which conductor carries what function without needing to test every wire with a meter. Connecting a hot wire to a ground terminal -- or mixing up neutrals and hots -- can cause electrocution, fires, or equipment damage.
Color codes are defined by national electrical codes and international standards. While the principles are similar worldwide (hot, neutral, ground), the actual colors vary significantly between countries. If you work on imported equipment or travel for electrical work, knowing these differences is crucial.
United States Wire Color Codes (NEC)
The National Electrical Code (NEC) governs wire colors in the United States. Here are the standard colors for 120/240V residential and commercial wiring:
Single-Phase (120V/240V)
- Black -- Hot (Line 1, ungrounded conductor)
- Red -- Hot (Line 2, used in 240V circuits and 3-way switch travelers)
- White -- Neutral (grounded conductor)
- Green -- Equipment ground
- Bare copper -- Equipment ground
- Green with yellow stripe -- Equipment ground (isolated ground)
Three-Phase (208V/480V)
- Black -- Phase A
- Red -- Phase B
- Blue -- Phase C
- White -- Neutral
- Green -- Ground
277/480V Three-Phase
- Brown -- Phase A
- Orange -- Phase B
- Yellow -- Phase C
- Gray -- Neutral
- Green -- Ground
Important NEC Rules
The NEC mandates colors only for neutral (white or gray) and ground (green or bare). Hot conductors can technically be any other color, but the conventions above are universally followed. Breaking these conventions is a code violation in practice because it creates confusion and safety hazards.
In conduit work with individual THHN conductors, electricians follow these color conventions strictly. In Romex (NM cable), colors are determined by the cable jacket: 14/2 has black (hot) and white (neutral), while 14/3 adds red as a second hot.
Canadian Wire Color Codes (CEC)
Canada follows the Canadian Electrical Code (CEC), which is similar to the NEC but has key differences:
- Black -- Hot (Phase A)
- Red -- Hot (Phase B)
- Blue -- Hot (Phase C)
- White -- Neutral
- Green or Green with yellow stripe -- Ground
The CEC is nearly identical to the NEC for residential wiring. The main difference appears in 3-phase industrial systems where Canadian practice may vary slightly from US conventions.
United Kingdom Wire Color Codes (BS 7671)
The UK updated its wire colors in 2004 (Amendment 2 to BS 7671) to align with European harmonized colors. Both old and new systems are still found in existing buildings.
Current UK Colors (post-2004)
- Brown -- Live (Line)
- Blue -- Neutral
- Green with yellow stripe -- Earth (protective conductor)
Three-Phase (Current)
- Brown -- L1
- Black -- L2
- Gray -- L3
- Blue -- Neutral
- Green with yellow stripe -- Earth
Old UK Colors (pre-2004, still found in buildings)
- Red -- Live
- Black -- Neutral
- Green or green/yellow -- Earth
If you encounter old UK wiring, never assume black is neutral based on US conventions -- in old UK wiring, black IS the neutral, not a hot conductor. Always test with a multimeter.
European Union / IEC Standard (IEC 60446)
The harmonized European colors (IEC 60446) match the current UK system:
- Brown -- Line (L1)
- Black -- Line (L2)
- Gray -- Line (L3)
- Blue -- Neutral
- Green with yellow stripe -- Protective Earth (PE)
These colors are used across the EU, including Germany, France, Italy, Spain, and Scandinavia. The harmonization effort began in the 1990s and is now standard across member states.
Australia and New Zealand Wire Colors (AS/NZS 3000)
Australia and New Zealand follow AS/NZS 3000 (the Wiring Rules):
- Red or Brown -- Active (Line)
- Black or Blue -- Neutral
- Green with yellow stripe -- Earth
Three-Phase
- Red -- Phase A
- White -- Phase B
- Blue -- Phase C
- Black -- Neutral
- Green/yellow -- Earth
Australia transitioned from the old red/black system to harmonized brown/blue colors, but red/black is still common in existing installations.
India Wire Color Codes (IS 732)
India follows IS 732:
Old Indian System
- Red -- Phase (Line)
- Black -- Neutral
- Green -- Earth
New Indian System (aligning with IEC)
- Brown -- Phase
- Blue -- Neutral
- Green with yellow stripe -- Earth
Three-Phase (India)
- Red -- Phase R
- Yellow -- Phase Y
- Blue -- Phase B
- Black -- Neutral
- Green -- Earth
Low-Voltage DC Wire Colors
DC wiring for automotive, solar, marine, and electronics applications follows different conventions:
Automotive (12V DC)
- Red -- Positive (+12V)
- Black -- Negative (ground)
Solar Panel Systems
- Red -- Positive DC
- Black -- Negative DC
- Green -- Equipment ground
- White -- Neutral (AC side of inverter)
Electronics and Hobby Projects
- Red -- Positive voltage (Vcc, V+)
- Black -- Ground (GND, 0V)
- Other colors -- Signal wires (no strict standard)
USB Cable Colors
- Red -- +5V power
- Black -- Ground
- White -- Data negative (D-)
- Green -- Data positive (D+)
Thermostat Wire Colors
Thermostat wiring uses its own color conventions:
- Red (R) -- 24V power from transformer
- White (W) -- Heat call
- Yellow (Y) -- Cooling call
- Green (G) -- Fan
- Blue or Brown (C) -- Common (24V return)
- Orange (O/B) -- Heat pump reversing valve
Quick Reference Table
| Function | USA (NEC) | UK/EU (IEC) | Australia | India (old) |
|---|---|---|---|---|
| Hot/Live L1 | Black | Brown | Red | Red |
| Hot/Live L2 | Red | Black | White | Yellow |
| Hot/Live L3 | Blue | Gray | Blue | Blue |
| Neutral | White | Blue | Black | Black |
| Ground/Earth | Green/bare | Green-yellow | Green-yellow | Green |
Safety Guidelines
- Always test -- Never rely solely on wire color. Use a multimeter or non-contact voltage tester to verify.
- Turn off power -- De-energize circuits before working on them. Lock out the breaker.
- Label everything -- When re-wiring or working in conduit, label wires at both ends.
- Follow local codes -- Wire color requirements vary by jurisdiction. Check with your local building department.
- Old wiring -- Buildings with pre-standard wiring may use non-standard colors. Test every conductor.
Creating Wire Color Reference Diagrams
Use CircuitDiagramMaker to create reference diagrams showing wire color codes for your specific application. The color-coded wire feature lets you assign red for hot, green for ground, blue for neutral, and any custom color for signal wires. Export as PNG or PDF for your reference binder.
CircuitDiagramMaker's AI circuit generator can also create properly color-coded diagrams -- just describe your circuit and mention the wiring standard you need to follow.
Conclusion
Wire color codes are fundamental to electrical safety. While the specific colors vary by country and application, the principle is universal: every conductor has a designated function, and its color communicates that function to anyone who works on the circuit.
Bookmark this guide as a reference, and always verify wire function with a tester before making connections. When in doubt, consult a licensed electrician and your local electrical code.
Create color-coded wiring diagrams with CircuitDiagramMaker -- the free online wiring diagram tool with 400+ symbols and built-in simulation.