Every color on an electrical wire has a specific meaning — and knowing them is essential for safe, error-free wiring. Thailand’s current standard (TIS 11-2553) aligns wire colors with the international IEC specification. This guide explains what each wire color means and how they’re used in single- and three-phase systems.
The Current Wire Color Standard (TIS 11-2553)
Thailand updated its wire color standard to align with the international IEC 60227 specification. The main colors and their meanings are:
| Color | Function | Role |
|---|---|---|
| Brown | Live (Phase/Line) | Supplies power to outlets and switches |
| Black | Second phase | Used for multi-phase equipment |
| Gray | Third phase | Typically for movable electrical devices |
| Blue | Neutral | Returns current to the power source |
| Green with yellow stripe | Ground / Earth | Prevents electric shock and circuit faults |
Single-Phase vs. Three-Phase Systems
Single-Phase (1Φ, 220V — residential)
- Brown = Phase (Line)
- Blue = Neutral
- Green/Yellow = Ground
Three-Phase (3Φ, 380V — industrial)
- Brown / Black / Gray = the three phases (L1, L2, L3)
- Blue = Neutral
- Green/Yellow = Ground
Why Wire Colors Matter
Standardized colors prevent installation errors, let electricians work consistently across regions, and — most importantly — enhance safety. Incorrect connections risk electrocution, equipment damage, short circuits, and fire.
Beyond Color: What Else to Check
- Cross-sectional area: 1.5, 2.5, 4.0 mm², etc.
- Voltage rating: 450/750V, 600/1000V.
- Wire type designation: VAF, NYY, THW.
- Certification mark: TIS 11-2553.
Get Correctly-Colored Standard Wire from TETA Intertrade
TETA Intertrade is a wire-wholesale specialist supplying TIS 11-2553 wire in the correct standard colors and full range of sizes for residential and industrial work. Standard colors from the start mean safer, faster, error-free installation.
Frequently Asked Questions (FAQs)
What color is the live wire under the current standard?
Brown is the live (phase/line) wire. In three-phase systems, black and gray are the second and third phases.
What do blue and green/yellow wires mean?
Blue is the neutral, which returns current to the source, and green with a yellow stripe is the ground (earth) wire, which protects against electric shock and faults.
Are the colors the same for single-phase and three-phase?
Neutral (blue) and ground (green/yellow) are the same in both. Single-phase uses brown for the one phase; three-phase adds black and gray for the second and third phases.
Besides color, what should I verify when buying wire?
Check the cross-sectional area, voltage rating, wire type (VAF, NYY, THW), and the TIS 11-2553 certification mark on the insulation.
