If you are looking for the standard wire ga amp chart for residential and commercial wiring, you are looking for NEC Table 310.16. For the most common household branch circuits (120V/240V, 100 amps or less), the baseline ampacities in the 60°C column are: 14 AWG = 15A, 12 AWG = 20A, and 10 AWG = 30A. However, picking the right wire requires understanding which temperature column applies to your specific breakers and terminals, and how bundling wires in conduit derates those baseline numbers.
How to Read This Wire GA Amp Chart
The table below is derived directly from NEC Table 310.16 (formerly 310.15(B)(16)). To use it correctly, you must understand the temperature columns and the rules governing them under NEC Article 110.14(C).
Which column applies to your installation? According to NEC 110.14(C)(1)(a), for circuits rated 100 amps or less, or for conductors sized 14 AWG through 1 AWG, you must use the 60°C column to determine the maximum breaker size, regardless of the wire's insulation rating. For circuits over 100 amps, or conductors larger than 1 AWG, you use the 75°C column. The 90°C column is almost exclusively used as a starting point for derating calculations (adjusting for heat and bundling), not for final breaker sizing.
How to use the quick-jump rows: The most frequently queried residential sizes (12, 10, 6, 4, and 2 AWG) are highlighted with anchor IDs in the table below for fast reference.
The Master Wire GA Amp Chart (NEC Table 310.16)
Assumptions: Copper and Aluminum conductors, 3 current-carrying conductors in a raceway, ambient temperature of 30°C (86°F). Source: NFPA NEC 2023/2026 Edition.
| Wire Size (AWG/kcmil) | Copper 60°C (Amps) | Copper 75°C (Amps) | Copper 90°C (Amps) | Aluminum 75°C (Amps) |
|---|---|---|---|---|
| 14 | 15 | 20 | 25 | N/A |
| 12 | 20 | 25 | 30 | N/A |
| 10 | 30 | 35 | 40 | N/A |
| 8 | 40 | 50 | 55 | 40 |
| 6 | 55 | 65 | 75 | 50 |
| 4 | 70 | 85 | 95 | 65 |
| 3 | 85 | 100 | 115 | 75 |
| 2 | 95 | 115 | 130 | 90 |
| 1 | 110 | 130 | 145 | 100 |
| 1/0 | 125 | 150 | 170 | 120 |
| 2/0 | 145 | 175 | 195 | 135 |
| 3/0 | 165 | 200 | 225 | 155 |
| 4/0 | 195 | 230 | 260 | 180 |
Derating and Edge Cases: What the Chart Cannot Tell You
The wire ga amp chart above assumes perfect conditions: an ambient temperature of 86°F (30°C) and no more than three current-carrying conductors in a single conduit. When jobsite conditions deviate, you must apply derating factors.
How derating rows modify the base value: If you pull four to six current-carrying conductors through a single PVC conduit, NEC Table 310.15(C)(1) requires you to multiply the wire's ampacity by 80%. For example, if you have five 12 AWG THHN wires (rated 30A in the 90°C column) in one pipe, the derated ampacity is 30A × 0.80 = 24A. Because 24A is still above the 20A terminal limit for a standard 60°C breaker, you can still use a 20A breaker. But if you bundled nine conductors (70% derating), 30A × 0.70 = 21A, and you would be forced to upsize to 10 AWG wire to maintain a 20A circuit safely. According to the Copper Development Association, always start your derating math from the 90°C column, but never terminate on a breaker that exceeds the 60°C/75°C column limits.
What the table cannot tell you: This chart dictates thermal safety (preventing the wire insulation from melting), but it does not account for voltage drop. If you are running a 12 AWG wire on a 20A circuit for 150 feet, the wire will not catch fire, but the voltage at the receptacle will drop below 114V (a 5% drop on a 120V nominal system), which can damage motor-driven appliances like refrigerators or HVAC blowers. For runs exceeding 100 feet, always run a separate voltage drop calculation and expect to upsize your wire by one or two AWG steps.
Frequently Asked Questions
Can I use the 90°C column for my 20-amp residential breaker?
No. While THHN/THWN-2 wire insulation is rated for 90°C, the physical brass and steel lugs inside standard residential breakers and receptacles are typically rated for a maximum of 75°C, and NEC 110.14(C) mandates using the 60°C column for circuits 100A and under. If you size a breaker to the 90°C column (e.g., putting a 25A breaker on 12 AWG wire), the wire will survive, but the breaker terminal will overheat and degrade over time.
How does bundling wires in conduit change my wire ga amp chart lookup?
When you bundle more than three current-carrying conductors (hot and neutral wires, but usually not the bare ground) in a single conduit, the trapped heat reduces the wire's ability to dissipate thermal energy. You must apply a derating multiplier (from 80% down to 40%) to the 90°C column ampacity. If the resulting number is lower than your breaker size, you must upsize the wire gauge.
Why is my 4 AWG aluminum wire rated lower than 4 AWG copper?
Aluminum has a higher electrical resistance than copper (roughly 61% of copper's conductivity). To carry the same current without overheating, aluminum wire must be physically thicker. In the 75°C column, 4 AWG copper handles 85 amps, while 4 AWG aluminum handles only 65 amps. For aluminum to match 4 AWG copper's 85A capacity, you must upsize to 2 AWG aluminum.
Does the wire ga amp chart account for voltage drop over long distances?
No. The wire ga amp chart only ensures the wire will not overheat and cause a fire under a specific continuous load. It does not guarantee that the voltage at the end of the run will remain within the acceptable 3% to 5% tolerance. For long feeder runs (e.g., powering a detached garage or a well pump 200 feet away), you must calculate voltage drop using the wire's resistance per 1,000 feet and the total one-way distance, often requiring you to upsize the wire beyond what the ampacity chart strictly requires.
