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Choosing the correct copper wire size depends on three main factors:
- The current (Amps) being used.
- The wire length (the longer the length, the larger the wire needed).
- The type of application (surface mounting / conduit / motor work, etc.).
Choosing a wire that’s too small → the wire will overheat, experience voltage drop, and risk burning.
Choosing a wire that’s too large → safer, but unnecessarily high cost.
Copper wire size selection chart (for general use)
Approximate value for a 220V household electrical system.
| Cable size (sq.mm.) | It can receive approximately | What is it used for? |
|---|---|---|
| 1.5 mm² | ~10 A | Lighting |
| 2.5 mm² | ~16–20 A | General electrical outlet |
| 4 mm² | ~25–32 A | Small air conditioner / water heater |
| 6 mm² | ~32–40 A | Large air conditioner / high load |
| 10 mm² | ~45–55 A | Sub Main |
| 16 mm² | ~60–75 A | Main house |
| 25 mm² | ~80–100 A | Factory / Heavy Load |
Example: Select for practical use.
Residential Buildings
- Light Bulbs → 1.5 mm²
- Plugs → 2.5 mm²
- Air Conditioners → 4–6 mm²
- Main House Cable → 10–16 mm²
Machinery/Motors
Requires consideration of actual motor power and current; typically starts from 4 mm² and above.