🔥 Wire Ampacity Chart (NEC Table 310.16)
The full copper and aluminum table — current code — plus the one thing everyone gets wrong: which temperature column you're allowed to use.
The chart
Amps each wire can carry continuously (up to three current-carrying wires in a cable or conduit, ordinary room temperature). These values are identical in the 2017, 2020, and 2023 NEC editions — we verified that against the published tables, so this chart is current by construction:
| Size | Copper | Aluminum | ||||
|---|---|---|---|---|---|---|
| 60°C | 75°C | 90°C | 60°C | 75°C | 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 | 125 | 150 | 170 | 100 | 120 | 135 |
| 2/0 | 145 | 175 | 195 | 115 | 135 | 150 |
| 3/0 | 165 | 200 | 225 | 130 | 155 | 175 |
| 4/0 | 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 |
Source-verified against two verbatim NEC table reproductions. Small-conductor breaker caps (NEC 240.4(D)) still apply: 14 Cu → 15 A breaker, 12 Cu → 20 A, 10 Cu → 30 A, 12 Al → 15 A, 10 Al → 25 A, regardless of column. Interactive version with the caps built in: Ampacity Check.
Which column am I allowed to use?
This is the single most-argued ampacity question on every electrician forum, and the rule is simpler than the arguments: use the column of your weakest link. The wire's insulation has a rating (THHN is 90°C), but the breaker lugs and receptacle terminals it lands on are usually rated 75°C — and Romex/NM-B cable is capped at the 60°C column by code no matter what its conductors say. So in practice: NM-B → 60°C column. THHN in conduit on standard equipment → 75°C column. The 90°C column is mostly useful as the starting point for derating calculations (hot attics, bundled cables), not as a rating you deliver to a breaker.
Does voltage change ampacity?
No — and this surprises a lot of the 12-volt crowd. A #10 wire can carry the same ~30 A whether it's a 12 V trolling-motor feed or a 240 V circuit. What changes brutally with voltage is voltage drop: losing 3 volts means losing 1.3% of a 240 V circuit but a crushing 25% of a 12 V one. That's why low-voltage wiring runs so much fatter than its amps suggest — check yours in the Voltage Drop calculator (it has a DC mode for exactly this).
What this chart doesn't cover
Normal conditions only: hot environments, more than three current-carrying conductors bundled together, and continuous loads (3+ hours → 80% rule) all reduce these numbers. A derating upgrade to our Ampacity tool is on the roadmap.