AWG Ampacity Chart: Full NEC Table 310.16 Wire Gauge Amp Ratings

Note: this chart covers NEC building wire — the wire behind your walls and panel — not car audio, marine, or speaker wire gauge, which use different ampacity assumptions.

If you just want one number

Most homes use copper wire. Use the 75°C column unless you know your breaker and outlets are rated higher — that's the standard rating for most modern panels and receptacles. If you're bundling several wires together or running through a hot attic, keep reading past the chart, because that 75°C number can still drop.

AWG	Cu 60°C	Cu 75°C	Cu 90°C	Al 60°C	Al 75°C	Al 90°C
14	15A	20A	25A	—	—	—
12	20A	25A	30A	15A	20A	25A
10	30A	35A	40A	25A	30A	35A
8	40A	50A	55A	35A	40A	45A
6	55A	65A	75A	40A	50A	55A
4	70A	85A	95A	55A	65A	75A
3	85A	100A	115A	65A	75A	85A
2	95A	115A	130A	75A	90A	100A
1	110A	130A	145A	85A	100A	115A
1/0	125A	150A	170A	100A	120A	135A
2/0	145A	175A	195A	115A	135A	150A
3/0	165A	200A	225A	130A	155A	175A
4/0	195A	230A	260A	150A	180A	205A

Values assume not more than three current-carrying conductors, 30°C (86°F) ambient — NEC Table 310.16. Highlighted rows (14/12/10 AWG) get a separate overcurrent cap below.

Why 14, 12 and 10 AWG don't get their full table rating

NEC 240.4(D) caps small copper conductors regardless of insulation type: 14 AWG at 15A, 12 AWG at 20A, 10 AWG at 30A. Aluminum and copper-clad aluminum sit one step lower: 12 AWG at 15A, 10 AWG at 25A.

Why it works this way

Line up those capped numbers against the chart above and they match the 60°C column exactly. The rule locks small conductors to their 60°C rating no matter what insulation you use, because most breaker and lug terminals are only rated for 60°C or 75°C — the wire's higher-temperature rating doesn't help if the connection point can't take it.

Ambient temperature derating

Table 310.15(B)(1) requires a correction factor once ambient temperature climbs past the 30°C (86°F) baseline. A conductor with 90°C insulation running through 36-40°C (96-104°F) ambient — a hot attic in summer — gets multiplied by 0.91. Go up to 41-45°C and the factor drops to 0.87.

Bundling / conductor-count derating

Table 310.15(C)(1) kicks in once you bundle 4 or more current-carrying conductors in the same raceway or cable. Four to six conductors get an 80% (0.80) adjustment factor, seven to nine drop to 70%, and it keeps falling as the bundle grows.

Worked example: heat + bundling together

Neither derating factor is hard on its own — the mistake is applying only one and stopping. Here's both, chained, for the scenario in the widget above.

Read the 90°C base ampacity off the chart: 10 AWG copper = 40A.
Apply the ambient correction for 36-40°C: 40A × 0.91 = 36.4A.
Apply the bundling adjustment for 4-6 conductors: 36.4A × 0.80 = 29.12A.
Check against the 240.4(D) cap for 10 AWG (30A) — 29.12A is already lower, so the derated number governs.
Round down to the nearest standard breaker size (NEC 240.6(A)): 25A.

That same 10 AWG wire in a cool basement with only two conductors keeps its full 30A-capped rating. The heat and the bundling cost 5 amps here, not the gauge.

Copper vs. aluminum at the same gauge

Aluminum runs roughly one full gauge size behind copper for the same ampacity — a 2 AWG aluminum conductor carries less current than a 2 AWG copper conductor at every temperature rating in the chart. That's a real conductivity difference, which is why aluminum feeders are typically sized up rather than swapped in gauge-for-gauge.

⚠ NEC 2026 vs. 2026

This chart's values are NEC 2026 numbers. NEC 2026 is published, but state-by-state adoption is still in progress and moves at different speeds in different jurisdictions — check your local adopted edition rather than assuming one nationwide date. Section numbers can shift slightly between editions; the ampacity values themselves have stayed consistent. Confirm the current section numbers with your inspector before citing them on a permit.

Common ampacity mistakes

The most common one is sizing a breaker off the 90°C column directly, ignoring that most terminals are only rated for 60°C or 75°C. Close behind is skipping derating entirely on a bundled or attic run — a wire that's fine in a cool basement can be overloaded in a hot attic even with an identical breaker. Using aluminum ampacity numbers on a copper wire (or the reverse) is a smaller but real one too.

Frequently asked questions

Wire & CircuitIs a wire gauge amp chart the same for house wiring and car audio?

No. Car audio and speaker wire gauge charts use different ampacity assumptions than NEC Table 310.16, which governs fixed building wiring. This page covers NEC building-wire ampacity only.
⚡ Wire Size calculator →

Code & SafetyCan I use the 90°C ampacity of a THHN wire to size my breaker?

Usually no. Most breakers and lugs are only rated for 60°C or 75°C termination temperatures under NEC 110.14(C), so that lower column is typically the real ceiling even if the insulation is rated 90°C.

Wire & CircuitWhy is 12 AWG copper wire rated for 20A instead of 25A or 30A?

Table 310.16 lists 12 AWG copper at 25A (75°C) or 30A (90°C), but NEC 240.4(D) caps it at 20A for overcurrent protection regardless of insulation — small conductors have less thermal mass than their raw ampacity number suggests.
⚡ Breaker Size calculator →

Code & SafetyDo I need to derate wire in a hot attic?

Yes, once ambient temperature passes 30°C (86°F), which most attics do in summer. A 90°C-rated conductor in 36-40°C ambient gets multiplied by 0.91 before you check it against your load.

Wire & CircuitHow many wires can I bundle before I have to derate for conductor count?

Derating starts at 4 or more current-carrying conductors in the same raceway or cable. Four to six get an 80% adjustment factor, seven to nine get 70%, and it keeps dropping as the bundle grows.

Code & SafetyWhich NEC edition's numbers does this chart use?

NEC 2026 values. NEC 2026 is published, but state adoption is still in progress and varies by jurisdiction — confirm your local adopted edition and exact section numbers with your inspector.

Dr. Artie Vance

Technical reviewer · Ph.D. in Physics, MIT · 14 years' experience · Cross-checked against NEC 2026 & 2026

This guide is for general information based on the National Electrical Code. Local codes and your authority having jurisdiction (AHJ) may differ. Electrical work can be dangerous, so when in doubt, hire a licensed electrician.