Ampacity by temperature rating
| Temperature rating | Ampacity | Typical insulation |
|---|---|---|
| 60°C | 25 A | — |
| 75°C | 30 A | THW |
| 90°C | 35 A | THHN / THWN-2, XHHW-2 |
Reference tables · Aluminum ampacity
2023 NEC · Table 310.16
10 AWG aluminum wire ampacity
At a 75°C termination rating, 10 AWG aluminum carries 30 A under the published table's basis conditions — 30°C ambient, no more than three current-carrying conductors. Overcurrent protection is separately capped at 25 A by the small-conductor rule.
What 10 AWG aluminum is used for
10 AWG aluminum is capped at 25 A by the small-conductor rule, which places it between the common 20 A and 30 A circuit sizes and makes it an awkward fit for most branch work.
Note the gap between the table and the ceiling. The 90°C column reads 35 A, but a 10 AWG aluminum conductor cannot be protected above 25 A regardless — the small-conductor rule sets that ceiling independently of ampacity. The higher table value exists so the conductor has headroom to be derated from, not so it can be put on a larger breaker.
Terminations usually decide the practical answer. Breakers and equipment are typically listed for 60°C or 75°C, so even 90°C-rated insulation on this conductor is normally limited to the 30 A column at the terminals. Check the equipment's listing rather than assuming.
Derating
Ampacity in real conditions
| Ambient | 3 conductors | 4 conductors | 7 conductors | 10 conductors | 21 conductors |
|---|---|---|---|---|---|
| 20°C | 25 A | 25 A | 23.3 A | 16.7 A | 15 A |
| 30°C | 25 A | 24 A | 21 A | 15 A | 13.5 A |
| 40°C | 25 A | 21.1 A | 18.5 A | 13.2 A | 11.9 A |
| 50°C | 22.5 A | 18 A | 15.7 A | 11.3 A | 10.1 A |
Properties
| Circular mils | 10,380 |
|---|---|
| DC resistance | 2.04 Ω per 1000 ft |
| Ampacity at 75°C | 30 A |
| Overcurrent ceiling | 25 A (small-conductor rule) |
| Largest standard breaker | 25 A |
| Area, THHN / THWN-2 | 0.0211 in² |
| Area, XHHW-2 | 0.0243 in² |
| Area, THW | 0.0333 in² |
Voltage drop over distance
Single-phase 240 V, carrying 25 A on 10 AWG aluminum.
| One-way distance | Drop | Within 3%? |
|---|---|---|
| 25 ft | 1.06% | Yes |
| 50 ft | 2.13% | Yes |
| 100 ft | 4.25% | No |
| 150 ft | 6.38% | No |
| 200 ft | 8.51% | No |
| 300 ft | 12.76% | No |
Source: NFPA 70, National Electrical Code, Table 310.16; NFPA 70, National Electrical Code, Table 310.15(B)(1)(1); NFPA 70, National Electrical Code, Table 310.15(C)(1); NFPA 70, National Electrical Code, Chapter 9, Table 8. Published by NFPA.NEC 2023
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