The wire color code for 3 phase depends entirely on your region and the system voltage. In the US, a standard 120/208V 3-phase system uses Black, Red, and Blue for the phases, while a 277/480V system uses Brown, Orange, and Yellow. In Europe and regions following IEC standards, the 230/400V 3-phase colors are Brown, Black, and Grey. Ground is universally Green or Green/Yellow, and Neutral is White/Grey (US) or Blue (IEC).
The Master 3-Phase Wire Color Code Reference Table
Use this table as your primary bench and jobsite reference. It covers the most common 3-phase configurations you will encounter in commercial, industrial, and heavy residential panels.
| System Type & Voltage | Phase A (L1) | Phase B (L2) | Phase C (L3) | Neutral | Ground |
|---|---|---|---|---|---|
| US 120/208V Wye (NEC) | Black | Red | Blue | White (or Grey) | Green / Bare |
| US 277/480V Wye (NEC) | Brown | Orange | Yellow | Grey (or White) | Green / Bare |
| US 240V High-Leg Delta | Black (120V to N) | Orange (208V to N) | Blue (120V to N) | White (or Grey) | Green / Bare |
| IEC 230/400V Wye (EU/Global) | Brown | Black | Grey | Blue | Green/Yellow |
| Old UK (Pre-2004) | Red | Yellow | Blue | Black | Green/Yellow |
Regional Variants and the "Rows People Get Wrong"
Color codes are not universal, and assuming a wire's function based on a single global standard is a fast track to a dead short or a shock hazard. Here is how regional standards diverge, followed by the specific table rows that cause the most field errors.
NEC vs. IEC: The Core Divergence
In the US, the National Electrical Code (NEC) dictates color coding primarily for branch circuits (Article 210.5) and high-leg delta systems (Article 310.110(C)(2)). For 208V branch circuits, you must use Black/Red/Blue. For 480V branch circuits, you must use Brown/Orange/Yellow. However, for feeders, the NEC allows any color except white, grey, or green, provided you maintain consistency throughout the facility and mark them with phasing tape at terminations.
Conversely, the IEC 60446 standard (adopted across Europe, the UK post-2004, and much of Asia) strictly mandates Brown/Black/Grey for all 3-phase line conductors, regardless of whether it is a 400V or 690V system. The neutral is always blue, and the protective earth (PE) is always green-and-yellow striped.
The Rows People Get Wrong
The most dangerous row in the table above is the US 240V High-Leg Delta. In this older industrial configuration, Phase B (the "high leg" or "wild leg") measures 208V to ground, while Phases A and C measure 120V to ground. If an electrician mistakenly lands the Orange (Phase B) wire on a standard 120V single-pole breaker expecting 120V, they will instantly destroy the connected 120V equipment and create a severe fire hazard. The NEC strictly mandates that the high leg must be colored Orange and must be landed on the "B" phase (usually the center busbar) in the panel.
The 480V vs. 208V Mix-up: In the US, using Black/Red/Blue for a 480V circuit is a direct violation of NEC 210.5(C)(2). Yet, in older facilities built before the 2008 NEC updates, you will frequently find 480V circuits wired in Black/Red/Blue. If you are retrofitting or troubleshooting, never assume Black/Red/Blue means 208V; always meter it.
The Old UK Legacy: If you are working in the UK or on imported European machinery built before 2004, you will encounter Red/Yellow/Blue phases with a Black neutral. Treat Black as a live neutral and Blue as a live phase in these legacy systems. Do not mix pre-2004 and post-2004 wiring in the same conduit without explicit, permanent labeling at every junction.
Safe Interpretation When Markings Are Faded or Missing
THHN insulation degrades under UV exposure, high ambient heat, and chemical off-gassing. A bright blue wire in a 90°C rooftop conduit can fade to a pale, dusty grey over a decade. When you open a panel and the colors are ambiguous, follow this verification protocol:
- De-energize and Lockout/Tagout (LOTO): If you are doing any physical termination work, kill the upstream breaker. Never trust faded colors to identify a neutral while the circuit is live.
- Look for Phasing Tape: Professional electricians wrap 3M Super 33+ or equivalent vinyl tape around the wire at the panel lug and the device termination. If the wire is grey but has a 2-inch wrap of red tape at the lug, it is Phase B.
- Test with a CAT III/IV Multimeter: If the circuit must remain live for diagnostic purposes, use a properly rated meter (like a Fluke 87V or 117).
- Measure Phase-to-Ground: On a 208V Wye, all three phases will read ~120V. On a 480V Wye, all three will read ~277V.
- Measure Phase-to-Phase: You should read the nominal system voltage (208V, 480V, or 400V) between any two line conductors.
- Identify the High Leg: If you measure ~208V from a phase to ground on a 240V Delta system, you have found the high leg. Mark it immediately with orange tape.
- Verify the Neutral: Measure Phase-to-Neutral. It should read the line-to-neutral voltage (120V, 277V, or 230V). If you measure 0V or a floating ghost voltage (e.g., 40V), you are likely measuring between two phases or the wire is broken upstream.
3-Phase Wire Color Code FAQ
What is the wire color code for 3 phase 208V vs 480V in the US?
Under current NEC guidelines, a 120/208V 3-phase branch circuit must use Black (Phase A), Red (Phase B), and Blue (Phase C), with a White or Grey neutral. A 277/480V 3-phase branch circuit must use Brown (Phase A), Orange (Phase B), and Yellow (Phase C), with a Grey or White neutral. In both cases, the equipment grounding conductor is Green, Green/Yellow, or bare copper.
Can I use black, red, and blue wire for a 480V 3-phase circuit?
No, not for new branch circuit installations. NEC Article 210.5(C) explicitly requires Brown, Orange, and Yellow for 480V branch circuits to prevent electricians from accidentally connecting 277V lighting or 208V equipment to a 480V supply. However, if you are pulling feeder conductors to a subpanel, the NEC does not mandate specific phase colors for feeders, provided they are not white, grey, or green, and provided you maintain a consistent color scheme throughout the facility and document it on the panel directory.
Why is the high-leg delta phase colored orange?
The high-leg delta system provides both 240V 3-phase power for motors and 120V single-phase power for lighting. However, the center-tapped transformer winding creates a "wild leg" (Phase B) that sits at 208V to ground, rather than 120V. The NEC mandates the color Orange for this specific conductor (Article 310.110(C)(2)) to serve as a high-visibility visual warning. If an electrician sees an orange wire, they immediately know not to land it on a standard 120V single-pole breaker or a 120V receptacle.
Does the NEC require specific colors for 3-phase conductors in all applications?
The NEC is highly specific about branch circuits (Article 210) and the high-leg delta (Article 310), but it is surprisingly lenient on feeders and service entrance conductors. For large feeder cables (often pulled in parallel using 2/0 AWG or larger THHN), electricians frequently use black THHN for all three phases and apply black, red, and blue (or brown, orange, yellow) phasing tape at every termination point. This is fully code-compliant as long as the panel directory clearly identifies the color-coding scheme used in that specific installation. Always consult your local Authority Having Jurisdiction (AHJ), as some local inspectors enforce stricter internal color-coding rules than the base NEC.
For more on safe electrical practices and standard compliance, refer to the OSHA Electrical Safety guidelines and your local electrical code authority.
