Understanding the 3-phase wire color code is essential when installing or maintaining electrical systems in commercial and industrial environments. Proper color coding ensures safe, standardized wiring practices and helps prevent costly mistakes.
3 phase wire color code chart
📘 What Is 3-Phase Power?
3-phase power is a common method of alternating current (AC) electricity distribution, especially in industrial and commercial settings. It uses three 'hot' conductors, often with a neutral and ground wire.
⚡ 3-phase systems are more efficient for large loads and heavy equipment than single-phase systems.
🟦 3-Phase Wire Color Code Chart (U.S. NEC)
The National Electrical Code (NEC) provides standard color codes for identifying conductors in 3-phase systems. These vary by voltage level.
🔹 3-Phase 120/208V AC – Wye Configuration (Common in commercial buildings)
| Wire Function | Color (U.S. NEC) |
|---|---|
| Phase A | Black |
| Phase B | Red |
| Phase C | Blue |
| Neutral | White |
| Ground | Green or Bare |
🔸 3-Phase 277/480V AC – Wye Configuration (Common in industrial settings)
| Wire Function | Color (U.S. NEC) |
|---|---|
| Phase A | Brown |
| Phase B | Orange |
| Phase C | Yellow |
| Neutral | Gray |
| Ground | Green or Bare |
🔻 Delta Configurations (Ungrounded or Corner-Grounded)
Delta systems are less common but used in specific industrial and motor-heavy applications. These may not have a neutral wire.
Note: Color codes may vary or be custom-labeled. NEC requires clear marking of ungrounded conductors.
⚠️ NEC Requirements & Best Practices
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🔌 Neutral wires must be white (120/208V) or gray (277/480V).
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⚠️ Ground wires must be green, green/yellow, or bare copper.
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🚫 Do not use neutral or ground colors for hot wires.
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🟠 Orange is reserved for identifying a high-leg in a delta system (where applicable).
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✅ Wires must be labeled or marked when deviating from standard color codes.
Always check NEC Article 210 and 310, and confirm with local electrical codes, which may impose additional requirements.
🔧 Common 3-Phase Wiring Scenarios
🏢 120/208V Wye – Commercial Panels
Used in office buildings and small commercial applications:
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Powers standard 120V outlets and lighting
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Can also supply 208V equipment (e.g., HVAC units)
🏭 277/480V Wye – Industrial Panels
Used in warehouses, factories, and large buildings:
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277V used for lighting systems
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480V used for motors, compressors, heavy equipment
🛠 Sample Wiring Layout (120/208V)
| Terminal | Wire Color | Description |
|---|---|---|
| L1 | Black | Phase A (hot) |
| L2 | Red | Phase B (hot) |
| L3 | Blue | Phase C (hot) |
| N | White | Neutral |
| G | Green | Ground |
🧯 Safety Reminders
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Always de-energize circuits before working.
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Use a voltage tester before touching wires.
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Double-check voltage ratings and wiring diagrams.
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Label wires clearly if color coding is not standard.
📎 Downloadable 3-Phase Color Code Chart (PNG/PDF)
Would you like a visual chart or printable PDF version of this 3-phase wiring color code guide? I can generate one for your use.
🧾 Conclusion
Using the correct 3-phase wire color code ensures safe and code-compliant installations in commercial and industrial settings. Whether you’re wiring a panel, connecting motors, or upgrading a building's power system, follow NEC standards and double-check your configuration.
