9 AWG (American Wire Gauge) wire specifications: 2.9064 mm diameter, 6.6342 mm² area. Resistance, weight, and common uses.
| Diameter | 2.9064 mm · 0.114424" · 114.42 mils |
| Cross-sectional area | 6.6342 mm² · 13,093 circular mils |
| Resistance (copper, 20°C) | 2.5987 Ω/km · 0.7921 Ω/1000ft |
| Resistance (aluminum, 20°C) | 4.2602 Ω/km · 1.2985 Ω/1000ft |
| Ampacity — copper 60°C | — A |
| Ampacity — copper 75°C | — A |
| Ampacity — copper 90°C | — A |
| Ampacity — aluminum 75°C | — A |
| Weight (copper) | 59.442 kg/km · 39.943 lbs/1000ft |
| Weight (aluminum) | 17.912 kg/km · 12.037 lbs/1000ft |
| Closest IEC 60228 size | 6 mm² |
| Skin depth at 60 Hz | 8.531 mm |
| Type | Temperature | Description |
|---|---|---|
| THHN/THWN-2 | 90°C dry / 75°C wet | Most common for building wire |
| XHHW-2 | 90°C dry and wet | Cross-linked polyethylene, moisture resistant |
| USE-2 | 90°C | Underground service entrance |
| NM-B (Romex) | 90°C | Non-metallic sheathed cable for residential |
| UF-B | 60°C | Underground feeder, direct burial |
9 AWG copper (2.906 mm diameter, 6.63 mm²) is uncommon in commercial wiring. It occasionally appears in thermocouple extension wire, industrial temperature-sensing circuits, and older European-manufactured equipment adapted for North American use. Most designs use 10 AWG or 8 AWG instead.
Per NEC Table 310.16, 9 AWG copper is rated 30 A at 60°C, 35 A at 75°C, and 40 A at 90°C. NEC 240.4(D) does not list 9 AWG among the sizes with fixed breaker limits (those are 14, 12, and 10 only), so overcurrent protection follows the general rules of NEC 240.4(B).