REFERENCE TABLE · CONSTRUCTION · ELECTRICAL
The full NEC Table 310.16 ampacity chart — copper 14 AWG through 4/0 and aluminum 12 AWG through 4/0, at 60°C, 75°C, and 90°C — plus an interactive lookup that reads any cell and names the max breaker. The default: 12 AWG copper at 60°C carries 20A, protected by a 20A breaker. Print the page for a clean one-page reference.
Pick a wire gauge, a conductor material, and a temperature column. The lookup reads the NEC Table 310.16 value, applies the NEC 240.4(D) small-conductor rule (copper: 14 AWG → 15A, 12 AWG → 20A, 10 AWG → 30A; aluminum: 12 AWG → 15A, 10 AWG → 25A; larger gauges take the next standard breaker size at or below the ampacity), and names typical uses.
Ampacity is the maximum current a wire can carry continuously without exceeding its insulation’s temperature rating. At the default — 12 AWG copper, 60°C column — the table reads 20A, and NEC 240.4(D) caps the breaker at 20A. The three columns exist because insulation rated 90°C tolerates more heat than 60°C insulation — but the circuit is limited by its weakest link: terminations, breakers, and devices are usually rated 60°C or 75°C, so the higher columns rarely govern in a home. And the 125% continuous-load rule: any load running 3+ hours (EV charger, water heater, space heater) may draw at most 80% of the rating — 16A max on that 20A circuit. The lookup below reports it for every combination.
| AWG | 60°C | 75°C | 90°C | Max breaker¹ |
|---|---|---|---|---|
| 14 | 15 | 20 | 25 | 15A |
| 12 | 20 | 25 | 30 | 20A |
| 10 | 30 | 35 | 40 | 30A |
| 8 | 40 | 50 | 55 | 40A |
| 6 | 55 | 65 | 75 | 50A |
| 4 | 70 | 85 | 95 | 70A |
| 3 | 85 | 100 | 115 | 80A |
| 2 | 95 | 115 | 130 | 90A |
| 1 | 110 | 130 | 145 | 110A |
| 1/0 | 125 | 150 | 170 | 125A |
| 2/0 | 145 | 175 | 195 | 125A |
| 3/0 | 165 | 200 | 225 | 150A |
| 4/0 | 195 | 230 | 260 | 175A |
Note: 14 AWG aluminum is not listed in NEC Table 310.16 — the aluminum table starts at 12 AWG.
| AWG | 60°C | 75°C | 90°C | Max breaker¹ |
|---|---|---|---|---|
| 12 | 15 | 20 | 25 | 15A |
| 10 | 25 | 30 | 35 | 25A |
| 8 | 35 | 40 | 45 | 35A |
| 6 | 40 | 50 | 55 | 40A |
| 4 | 55 | 65 | 75 | 50A |
| 3 | 65 | 75 | 85 | 60A |
| 2 | 75 | 90 | 100 | 70A |
| 1 | 85 | 100 | 115 | 80A |
| 1/0 | 100 | 120 | 135 | 100A |
| 2/0 | 115 | 135 | 150 | 110A |
| 3/0 | 130 | 155 | 175 | 125A |
| 4/0 | 150 | 180 | 205 | 150A |
¹ Max breaker uses the 60°C ampacity and the NEC 240.4(D) small-conductor rule — copper 14/12/10 AWG capped at 15/20/30A, aluminum 12/10 AWG capped at 15/25A; larger gauges take the next standard breaker size at or below the ampacity. The lookup above computes the breaker for the 75°C and 90°C columns too.
For the small gauges, the breaker is capped by rule — copper 14/12/10 AWG at 15/20/30A, aluminum 12/10 AWG at 15/25A — even when the 75°C or 90°C column allows more current. That 12 AWG copper reading 30A at 90°C? Still a 20A breaker in practice (and 15A if it were aluminum). This is the single most-misunderstood line in residential wiring, and it’s why the 90°C column is mostly a derating starting point, not a breaker-sizing column.
| Output | Formula | What it means |
|---|---|---|
| Ampacity | NEC Table 310.16 lookup by gauge, material, temperature column | 20A at the default (12 AWG copper, 60°C) — the continuous current the wire can carry. |
| Max breaker | 240.4(D) cap for small gauges; else largest standard size ≤ ampacity | 20A at the default. Standard sizes run 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250A. |
| Max continuous load | ampacity × 80% (the 125% rule, NEC 210.19(A)(1)) | 16A at the default — a load running 3+ hours may use at most 80% of the circuit rating, so size wire and breaker at 125% of the continuous load. |
| Typical uses | gauge → common residential application | 12 AWG: kitchen, bath, and 20A general circuits. 4/0 copper: 200A residential service entrance. |
Ampacity values are NEC Table 310.16 (NFPA 70) for not more than three current-carrying conductors in a raceway or cable at 30°C (86°F) ambient. Real installations derate: more than three current-carrying conductors in one raceway, ambient temperatures above 30°C, and rooftop conduit all reduce allowable ampacity — the 90°C column is the starting point for those calculations, not the answer. NM-B (Romex) is limited to the 60°C column for its final ampacity regardless of its 90°C-rated conductors. Aluminum terminations require CO/ALR-rated devices and anti-oxidant compound. This chart is a reference, not a design — local amendments apply, and electrical work must meet local code: hire a licensed electrician.
Bright Side Kit. "AWG Wire Ampacity Chart: NEC 310.16 Copper & Aluminum." https://brightoolbox.com/awg-wire-ampacity-chart/ Accessed October 24, 2026.Data sourcesThey’re insulation temperature ratings — how hot the wire’s insulation can safely get. Higher-rated insulation tolerates more current. But a circuit is limited by its lowest-rated part: if the breaker terminals are rated 75°C, you use the 75°C column even on 90°C-rated wire. In homes, 60°C usually governs because of NM-B cable and device terminations.
Because NM-B (Romex) — the cable in most residential walls — must use the 60°C column for its final ampacity, and most receptacles, switches, and breakers have 60°C or 75°C terminals. The 90°C column is real, but in residential work it’s mainly the starting point for derating calculations, not the number that sizes your breaker.
No. NEC 240.4(D) caps 12 AWG copper at 20A (and 12 AWG aluminum at 15A; 14 AWG at 15A, 10 AWG copper at 30A) regardless of what the 75°C or 90°C column says. The 12 AWG copper 90°C value of 30A does not authorize a 30A breaker — this is the most common and most dangerous misreading of the ampacity table.
14 AWG aluminum simply isn’t listed in NEC Table 310.16 — the aluminum table starts at 12 AWG (15A at 60°C). Small-gauge aluminum branch wiring has a troubled history (1970s-era connections), so the Code never standardized it. If the lookup told you “not listed,” that’s the table talking, not a bug.
Copper for branch circuits: more ampacity per gauge, simpler terminations. Aluminum is common and economical for large feeders and service entrances, where you upsize — e.g. 4/0 aluminum (150A at 60°C) where 2/0 copper (145A) would do. Aluminum demands CO/ALR-rated devices, proper torque, and anti-oxidant compound; never mix metals at a terminal not rated for it.
A load that runs 3 hours or more — an EV charger, a water heater, a space heater — counts as continuous, and the NEC (210.19(A)(1)) requires the circuit to be sized at 125% of the load. Flipped around: the continuous load may not exceed 80% of the rating — 16A max on a 20A circuit, 24A on a 30A circuit. That’s why a 48A EV charger needs a 60A breaker (48 × 1.25 = 60): the rule sizes the breaker first, and the wire follows the breaker.
Yes, beyond three current-carrying conductors. Table 310.16 assumes at most three; pack 4–6 current-carrying conductors in a raceway and you multiply by 80%, 7–9 by 70%, and so on (NEC 310.15(C)(1)). Hot attics and rooftop conduit need ambient-temperature correction on top. When in doubt, upsize the wire — copper is cheaper than a callback.