The Complete AWG Amps Chart: NEC 310.16 Wire Sizing Reference

For standard residential branch circuits, 14 AWG copper wire is rated for 15 amps, 12 AWG for 20 amps, and 10 AWG for 30 amps. These baseline values assume conductors with 60°C insulation operating in an ambient temperature of 30°C (86°F). However, real-world installations rarely match these baseline assumptions. Sizing wire correctly requires understanding temperature ratings, termination limits, and bundling derations.

The Master AWG Amps Chart (NEC Table 310.16)

The following data is extracted directly from NEC Table 310.16 (NFPA 70, 2023/2026 editions). This table dictates the allowable ampacities for insulated conductors rated up to 2000 volts.

How to read this table: The columns represent the maximum temperature rating of the wire's insulation (e.g., THHN is 90°C, THWN is 75°C, older TW is 60°C). The rows represent the American Wire Gauge (AWG) cross-sectional area. The intersecting cell provides the maximum continuous current the wire can carry without degrading the insulation, assuming no more than three current-carrying conductors in a raceway and an ambient air temperature of 30°C.

How to Read the Chart: Temperature Columns and Derating

Which Column Applies to Your Installation?

A common mistake is using the 90°C column just because you bought THHN wire. Per NEC 110.14(C), your final ampacity is limited by the weakest link in the circuit. Most standard residential breakers and receptacles have termination points rated for 75°C maximum. Furthermore, for circuits rated 100A or less (or wire sizes 14 AWG through 1 AWG), the NEC defaults to the 60°C column unless the equipment is explicitly listed and marked for 75°C.

How Derating Modifies the Base Value

The chart assumes a maximum of three current-carrying conductors in a conduit. When you bundle four or more wires together, they trap heat. NEC 310.15(C)(1) requires you to multiply the base ampacity by a derating factor.

Worked Example: You are pulling four 12 AWG THHN copper wires through a single conduit for two separate 20A circuits.
1. Base ampacity for 12 AWG in the 90°C column = 30A.
2. Derating factor for 4-6 conductors = 80% (0.80).
3. Adjusted ampacity = 30A × 0.80 = 24A.
4. Because 24A is still greater than the 20A breaker protecting the circuit, 12 AWG is legally compliant. If you added a fifth wire (derating drops to 70%), the math becomes 30A × 0.70 = 21A, which still passes, but you are getting dangerously close to the limit.

Quick-Jump Reference: Most Common Residential Wire Sizes

Use these bookmark-friendly anchors to quickly verify the most frequently queried wire sizes for standard home wiring.

14 AWG Copper

Ampacity: 15A (60°C column). Breaker: 15A max. Use case: Lighting circuits and low-draw receptacle circuits. Never use on a 20A breaker.

12 AWG Copper

Ampacity: 20A (60°C column). Breaker: 20A max. Use case: Standard kitchen, bathroom, and general-purpose 120V receptacle circuits. The workhorse of residential wiring.

10 AWG Copper

Ampacity: 30A (60°C column). Breaker: 30A max. Use case: Electric water heaters, window AC units, and 120V RV receptacles.

8 AWG Copper

Ampacity: 40A (60°C col) / 50A (75°C col). Breaker: 40A or 50A depending on termination ratings. Use case: Electric cooktops and spa disconnects.

6 AWG Copper

Ampacity: 55A (60°C col) / 65A (75°C col). Breaker: 60A (standard breaker size). Use case: Electric ranges, heavy-duty garage subpanels, and EV Level 2 chargers.

4 AWG Copper / 2 AWG Aluminum

Ampacity: 70A/85A (Cu) or 75A/90A (Al). Use case: Feeder wires for 100A subpanels. Note that while 2 AWG Aluminum in the 75°C column is rated for 90A, it is universally accepted on 100A breakers for residential subpanel feeds due to specific NEC residential feeder allowances, but always verify local AHJ interpretations.

What the AWG Amps Chart Cannot Tell You

While the Copper Development Association and the NEC provide these ampacity tables for thermal safety, they do not account for power quality over distance. Relying solely on this chart will lead to failures in specific scenarios.

Voltage Drop Over Long Runs

The AWG amps chart assumes the wire run is short enough that voltage drop is negligible. If you are wiring a detached shed 150 feet away and plan to draw 16A on a 20A circuit using 12 AWG wire, the wire will not melt (it is thermally safe), but your tools will only see ~110V.
The Fix: For runs over 50 feet, calculate voltage drop. A standard rule of thumb is to keep drop under 3% for branch circuits. In the 150-foot shed example, you must upsize to 8 AWG copper to maintain usable voltage at the load.

Extreme Ambient Temperatures

The chart is calibrated for 30°C (86°F). If you are routing conduit across the underside of a hot metal roof in a Texas summer, or through a commercial bakery's ceiling space, ambient temperatures can easily exceed 50°C (122°F). At 50°C ambient, the ampacity of 90°C THHN wire must be multiplied by a correction factor of 0.82. A wire that is perfectly safe in a climate-controlled basement will overheat and trip breakers in an unconditioned attic.

Short-Circuit and Fault Currents

Ampacity charts measure continuous thermal loading. They do not tell you if the wire can survive the magnetic and thermal forces of a 10,000-amp short circuit before the breaker trips. For service entrance conductors and main feeders, you must also verify the Available Fault Current (AFC) and ensure your wire and breaker combination has an adequate interrupting rating.