Copper and aluminum are the two main conductor materials for electrical wire, and each has clear strengths. Choosing the right one — and sizing it correctly — affects safety, cost, and performance. This guide compares copper vs. aluminum wire and shows where each is the better choice.
Copper Wire
- Superior conductivity (100% IACS standard).
- Better heat resistance and mechanical strength.
- Ideal for building interiors and control systems.
- Higher cost, but needs a smaller diameter for the same current.
- Greater flexibility, making it easier to install.
Aluminum Wire
- Lower conductivity — about 61% of copper.
- Requires a larger gauge for the same current capacity.
- Much lighter — roughly 3× lighter than copper.
- Significantly cheaper.
- Needs specialized bi-metal connectors to prevent corrosion at connection points.
Ampacity Comparison
Because aluminum conducts less well, it must be upsized by one to two sizes to carry the same current as copper:
| Copper | Aluminum (equivalent) | Approx. current |
|---|---|---|
| 16 mm² | 25 mm² | ~70–80 A |
| 25 mm² | 35 mm² | ~90–110 A |
Which Should You Use? Application Recommendations
- Residential: copper is preferred for interior wiring; aluminum is acceptable for main feeds when the correct connectors are used.
- Commercial: copper is favored for its reliability and space efficiency.
- Industrial: aluminum for long-distance mains; copper for motor circuits with high inrush currents.
Both options are equally safe when properly sized and installed per local electrical codes (Thailand’s EIT / MEA / PEA standards).
Get the Right Copper or Aluminum Wire from TETA Intertrade
TETA Intertrade is a wire-wholesale specialist stocking TIS-standard copper and aluminum wire in the full range of sizes, plus the correct connectors for aluminum terminations. We help you choose and size the right conductor for the job — safe, compliant, and cost-effective.
Frequently Asked Questions (FAQs)
Is copper always better than aluminum?
Not always. Copper has higher conductivity and strength and suits interior and control wiring, but aluminum is lighter and cheaper and is well suited to long main feeders. Both are safe when correctly sized and installed.
Why does aluminum wire need to be larger than copper?
Aluminum conducts about 61% as well as copper, so it must be upsized by one to two sizes to carry the same current. For example, copper 16 mm² is roughly equivalent to aluminum 25 mm².
Do I need special connectors for aluminum wire?
Yes. Aluminum requires bi-metal (aluminum-to-copper rated) connectors to prevent corrosion and loose connections where it meets copper terminals or other metals.
Which is more cost-effective?
Aluminum has a lower material cost and weight, which helps on long runs, but requires larger sizes and special connectors. Copper costs more but saves space and installs easily. The best value depends on the run length and application.
