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AWG Wire Gauge System
American Wire Gauge (AWG) specifies wire diameter in the US. Smaller AWG numbers mean larger wires. The system is based on drawing dies: more dies produce thinner wire. Wire gauge selection is critical for electrical safety since undersized wire overheats under load.
The NEC specifies minimum gauges for various loads. Each 6-gauge decrease doubles diameter; each 3-gauge decrease doubles area. AWG 0000 (4/0) is the largest standard gauge at 11.68 mm.
AWG Formula
Common Wire Gauges
| AWG | Diameter (mm) | Area (mm²) | Max Amps | Use |
|---|---|---|---|---|
| 14 | 1.63 | 2.08 | 25A | 15A circuits |
| 12 | 2.05 | 3.31 | 30A | 20A circuits |
| 10 | 2.59 | 5.26 | 40A | 30A circuits |
| 8 | 3.26 | 8.37 | 65A | 40A circuits |
| 6 | 4.11 | 13.30 | 80A | 50-60A |
Frequently Asked Questions
Why do smaller numbers mean bigger wire?
AWG number represents drawing steps. More steps produce thinner wire. It is counterintuitive but deeply established in the industry.
What gauge for 20A circuit?
12 AWG minimum per NEC. For long runs (50+ feet), consider 10 AWG to limit voltage drop.
Copper vs aluminum?
Aluminum has 61% of copper's conductivity. Use 2 sizes larger for same ampacity. Aluminum requires special AL-rated connectors.