For standard residential and commercial branch circuits using copper wire, the most queried AWG size chart values are straightforward: 14 AWG is rated for 15 amps, 12 AWG for 20 amps, 10 AWG for 30 amps, 8 AWG for 40 amps, and 6 AWG for 55 amps (typically protected by a 60A breaker). These baseline numbers assume a standard 30°C (86°F) ambient environment and no more than three current-carrying conductors in a raceway. However, pulling wire is only half the job; matching the conductor to the correct overcurrent protective device and termination temperature rating is where most DIY mistakes happen.

The Master AWG Size Chart (NEC Table 310.16)

This table is derived directly from National Fire Protection Association (NFPA) 70, specifically NEC Table 310.16. How to read this table: The rows represent the American Wire Gauge (AWG) size. The three ampacity columns correspond to the temperature rating of the wire's insulation (60°C, 75°C, and 90°C). The final column lists the standard maximum breaker size permitted by NEC 240.4, factoring in the small-conductor rules and standard breaker trip ratings. Bookmark the quick-jump rows below for the most common residential sizes.

AWG Size 60°C (140°F) Ampacity 75°C (167°F) Ampacity 90°C (194°F) Ampacity Standard Max Breaker
14 AWG 15A 20A 25A 15A
12 AWG 20A 25A 30A 20A
10 AWG 30A 35A 40A 30A
8 AWG 40A 50A 55A 40A / 50A*
6 AWG 55A 65A 75A 60A
4 AWG 70A 85A 95A 70A / 80A
3 AWG 85A 100A 110A 80A / 90A
2 AWG 95A 115A 130A 100A / 110A
1 AWG 110A 130A 145A 125A
1/0 AWG 125A 150A 170A 150A
2/0 AWG 145A 175A 195A 175A
3/0 AWG 165A 200A 225A 200A
4/0 AWG 195A 230A 260A 225A / 250A

*Note: 8 AWG can be protected at 50A only if the breaker and all downstream terminations are explicitly rated for 75°C. Otherwise, default to 40A.

Which Column Applies and How Derating Works

The most common mistake when using an AWG size chart is looking exclusively at the 90°C column because it offers the highest ampacity. Which column applies to your installation? According to NEC 110.14(C), for circuits rated 100 amps or less (which covers 14 AWG through 1 AWG), you must use the 60°C column unless the equipment (breakers, lugs, receptacles) is specifically marked and listed for 75°C. Most modern residential breakers and THWN-2 wire setups allow you to use the 75°C column for sizing, but the 60°C column remains the safest default for older panels or unknown terminations. For feeders over 100A, the 75°C column is the standard baseline.

How derating rows modify the base value: The ampacities in the table above assume an ambient temperature of 30°C (86°F) and no more than three current-carrying conductors in a conduit. If you are pulling wire through a hot attic (e.g., 110°F ambient) or bundling four or more current-carrying conductors in a single PVC pipe, you must apply derating factors.

The Derating Calculation Rule: Always start your derating math using the 90°C column. Multiply the 90°C ampacity by the correction factor found in NEC Table 310.15(C)(1). Once you have that adjusted number, compare it to the base 60°C or 75°C ampacity. The lower of the two numbers is your final legal ampacity.

For example, if you pull four 10 AWG THHN (90°C) current-carrying conductors through a conduit, the 90°C base is 40A. The derating factor for 4-6 conductors is 80%. 40A × 0.80 = 32A. Because 32A is higher than the 60°C base limit of 30A, your final ampacity is capped at 30A, and you must use a 30A breaker. If you added two more conductors (6 total, 80% derating still applies but let's say 9 wires at 70%: 40A × 0.70 = 28A), your final ampacity drops to 28A, meaning you can no longer use a 30A breaker and must step up to 8 AWG wire.

What This AWG Size Chart Cannot Tell You

While this copper AWG wire gauge chart is the foundation of circuit design, it is not a complete engineering tool. Here is what the table leaves out:

  • Voltage Drop: The NEC ampacity tables do not account for distance. If you are running a 6 AWG copper wire 150 feet to a detached garage subpanel, the wire can safely handle 55A-65A thermally, but the voltage drop at that distance will exceed the recommended 3% limit. You must upsize the wire (e.g., to 4 AWG or 3 AWG) purely to maintain voltage stability, even if the breaker size remains the same.
  • Conduit Fill Capacity: This chart tells you how much current the wire can carry, not how many wires physically fit inside a pipe. You must cross-reference NEC Chapter 9, Table 1 to ensure you are not exceeding 40% conduit fill for three or more wires, which prevents jamming during pulls and allows for heat dissipation.
  • Aluminum Equivalents: The values above are strictly for copper. Aluminum wire has higher resistance and lower thermal conductivity. As a general rule of thumb, aluminum requires jumping up two AWG sizes to match copper ampacity (e.g., 2 AWG Copper ≈ 1/0 AWG Aluminum).
  • Short Circuit Interrupting Ratings: The breaker size column assumes standard thermal limits. It does not verify that the breaker's AIC (Ampere Interrupting Capacity) rating is sufficient for the available fault current at your specific panel busbar.

AWG Size Chart FAQ: Long-Tail Questions Answered

What size breaker do I use for a 10 AWG wire?

The standard maximum breaker size for 10 AWG copper wire is 30 amps. Even though the 75°C column shows 35A and the 90°C column shows 40A, NEC 240.4(D) explicitly restricts 10 AWG copper to a 30A overcurrent device for general branch circuits. This "small conductor rule" exists to protect the wire from localized heating at terminations and minor overloads that wouldn't immediately trip a larger breaker but would slowly degrade the insulation over time.

Can I use the 90°C ampacity column to size my breaker?

No, not directly. The 90°C column is almost exclusively used as the starting point for derating calculations (adjusting for high ambient temperatures or bundling multiple wires in a conduit). The actual breaker size and termination limits are bottlenecked by the lowest temperature rating in the circuit path. Since most residential receptacles, switches, and standard breakers are rated for 75°C (or default to 60°C for circuits under 100A), your final breaker size must be based on those lower columns.

How does the AWG size chart change for aluminum wire?

Aluminum conducts electricity less efficiently than copper and expands/contracts more under thermal load, which can loosen terminations. To achieve the same ampacity found in the copper chart above, you generally need to increase the aluminum wire size by two AWG steps. For example, if a project calls for 4 AWG copper (85A at 75°C), you would need to use 2 AWG aluminum (90A at 75°C). Always use anti-oxidant paste (like Noalox) on aluminum terminations and torque lugs to the manufacturer's exact inch-pound specifications.

What AWG wire is needed for a 50 amp hot tub circuit?

For a standard 50-amp hot tub circuit, 6 AWG copper THWN-2 wire pulled through a conduit is the minimum requirement. At 60°C, 6 AWG is rated for 55A, which safely accommodates a 50A breaker. However, if the hot tub is located far from the main panel (typically over 60-80 feet), you must calculate voltage drop. In long-run scenarios, bumping up to 4 AWG copper is highly recommended to ensure the spa's heaters and pumps receive adequate voltage without tripping internal control board safeties.