NEC 310.16 · Wire ampacity
Allowable ampacity for copper and aluminum building wire at 60°C, 75°C, and 90°C — 14 AWG through 1000 kcmil, straight from NEC Table 310.16.
| Size | Cu 60°C | Cu 75°C | Cu 90°C | Al 60°C | Al 75°C | Al 90°C |
|---|---|---|---|---|---|---|
| 14 AWG | 15 | 20 | 25 | — | — | — |
| 12 AWG | 20 | 25 | 30 | 15 | 20 | 25 |
| 10 AWG | 30 | 35 | 40 | 25 | 30 | 35 |
| 8 AWG | 40 | 50 | 55 | 35 | 40 | 45 |
| 6 AWG | 55 | 65 | 75 | 40 | 50 | 55 |
| 4 AWG | 70 | 85 | 95 | 55 | 65 | 75 |
| 3 AWG | 85 | 100 | 115 | 65 | 75 | 85 |
| 2 AWG | 95 | 115 | 130 | 75 | 90 | 100 |
| 1 AWG | 110 | 130 | 145 | 85 | 100 | 115 |
| 1/0 AWG | 125 | 150 | 170 | 100 | 120 | 135 |
| 2/0 AWG | 145 | 175 | 195 | 115 | 135 | 150 |
| 3/0 AWG | 165 | 200 | 225 | 130 | 155 | 175 |
| 4/0 AWG | 195 | 230 | 260 | 150 | 180 | 205 |
| 250 kcmil | 215 | 255 | 290 | 170 | 205 | 230 |
| 300 kcmil | 240 | 285 | 320 | 195 | 230 | 260 |
| 350 kcmil | 260 | 310 | 350 | 210 | 250 | 280 |
| 400 kcmil | 280 | 335 | 380 | 225 | 270 | 305 |
| 500 kcmil | 320 | 380 | 430 | 260 | 310 | 350 |
| 600 kcmil | 350 | 420 | 475 | 285 | 340 | 385 |
| 750 kcmil | 400 | 475 | 535 | 320 | 385 | 435 |
| 1000 kcmil | 455 | 545 | 615 | 375 | 445 | 500 |
NEC Table 310.16 — based on 30°C (86°F) ambient and ≤3 current-carrying conductors. Apply ambient and conductor-count derating as required, and the 240.4(D) small-conductor limits (14 AWG = 15 A, 12 = 20 A, 10 = 30 A). Verify against the NEC edition adopted in your jurisdiction.
NEC Table 310.16 is the workhorse for sizing conductors. It gives allowable ampacity by conductor size, material (copper or aluminum), and insulation temperature rating, assuming a 30°C ambient and no more than three current-carrying conductors in the raceway or cable.
Pick the column that matches the lowest temperature rating in the circuit — most commonly the 75°C column for terminations, or 60°C for small equipment. The 90°C column is generally used only as a starting point for derating, not the final number. Then apply ambient-temperature and conductor-count correction factors, and respect the 240.4(D) small-conductor breaker limits.
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NEC Table 310.16 lists the allowable ampacity of insulated conductors rated up to 2000 V, installed in raceway, cable, or earth, based on an ambient temperature of 30°C (86°F) and no more than three current-carrying conductors. It is the primary table for sizing building wire.
Use the column matching the lowest temperature rating in the circuit — usually the 60°C column for terminations on equipment rated 100 A or less (and #1 AWG and smaller), and the 75°C column for most larger equipment. The 90°C column is generally used only for derating calculations, not final termination ampacity.
NEC 240.4(D) limits overcurrent protection regardless of the higher ampacity values: 14 AWG copper to 15 A, 12 AWG to 20 A, and 10 AWG to 30 A. So even though 14 AWG shows 20–25 A in the table, its breaker is capped at 15 A.
Yes. The table assumes 30°C ambient and three or fewer current-carrying conductors. Higher ambient temperatures (310.15(B)(1)) and four or more conductors in a raceway (310.15(C)(1)) require derating, which reduces the usable ampacity.
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