AWG Amps Chart: Complete NEC 310.16 Wire Sizing Reference

If you are looking for the most common AWG to amps conversions, here are the baseline numbers for standard residential copper wiring: 14 AWG is 15 amps, 12 AWG is 20 amps, 10 AWG is 30 amps, 8 AWG is 40 amps, and 6 AWG is 55 amps. These values assume copper conductors, a standard 30°C (86°F) ambient temperature, and no more than three current-carrying conductors in a raceway.

However, pulling a single number from memory is how DIYers trip breakers or, worse, melt terminal lugs. Wire ampacity is not a fixed property of the metal; it is a thermal limit dictated by the insulation wrapped around it and the equipment it connects to. Below is the complete reference data, the rules for selecting the correct column, and the real-world derating math that jobsite electricians use to keep installations safe and code-compliant.

The Complete AWG Amps Reference Chart (NEC Table 310.16)

The following data is sourced directly from NEC Table 310.16 (formerly 310.15(B)(16)), the authoritative standard for wire ampacity in the United States.

*Note on small conductors: Per NEC 240.4(D), the overcurrent protection for 14, 12, and 10 AWG copper wire is strictly limited to 15, 20, and 30 amps respectively, regardless of the higher values shown in the 75°C or 90°C columns.

Which Temperature Column Applies to Your Installation?

The most common mistake DIYers make is looking at a spool of 90°C THHN wire, reading the 90°C column, and assuming they can push that maximum current. In residential wiring, you almost never get to use the 90°C column for your final ampacity.

The rule governing this is NEC 110.14(C), which dictates that the temperature rating of the entire circuit is limited by its weakest link—usually the terminal lugs on your breakers, receptacles, and switches.

• The 60°C Column: You must use this column if your circuit is rated 100 amps or less, or uses wire sizes 14 AWG through 1 AWG, unless the equipment is explicitly marked for 75°C. Furthermore, if you are using NM-B cable (Romex), NEC 334.80 legally restricts its ampacity to the 60°C column, even though the individual THHN wires inside the sheath are rated for 90°C.
• The 75°C Column: You may use this column for circuits over 100 amps, or for smaller circuits where both the wire insulation and the equipment terminals are explicitly rated and marked for 75°C. Most modern commercial breakers and panel lugs are 75°C rated.
• The 90°C Column: In residential and light commercial work, this column is almost exclusively used as a starting point for derating calculations (explained below), not for determining the final breaker size.

How Derating Modifies Your Base Ampacity

The AWG amps table above assumes ideal conditions: an ambient temperature of 30°C (86°F) and no more than three current-carrying conductors bundled together. When you deviate from these conditions, the wire cannot dissipate heat as efficiently, and you must apply adjustment factors (derating) as outlined in NEC 310.15.

1. Bundling (More than 3 Current-Carrying Conductors):
When you pull 4 to 6 current-carrying wires through a single conduit, you must multiply the base ampacity by 80%. For 7 to 9 wires, the factor drops to 70%.

2. Ambient Temperature:
If your conduit runs through an attic that reaches 45°C (113°F) in the summer, you must apply a temperature correction factor. For 90°C THHN wire at 45°C, the correction factor is 0.87.

Real-World Derating Example:
You need to run a 20-amp circuit to an outdoor shed. You pull four current-carrying conductors (two hots, two neutrals for a multi-wire branch circuit) plus a ground wire through a conduit in an attic with a 40°C ambient temperature. You choose 10 AWG THHN copper.

1. Base ampacity from 90°C column: 40A.
2. Bundling factor (4 wires): 40A × 0.80 = 32A.
3. Temperature factor (40°C): 32A × 0.91 = 29.12A.
4. Final derated ampacity: 29.12A. Since this is greater than the 20A breaker protecting it, 10 AWG is acceptable. (Note: 12 AWG THHN would also mathematically work here, but 240.4(D) and practical voltage drop considerations often push electricians to 10 AWG for long shed runs).

What This AWG Amps Table Cannot Tell You

Ampacity charts only tell you the thermal limit of the insulation. They do not account for voltage drop. Per NEC informational notes (and strict code in some local jurisdictions), branch circuits should be designed to limit voltage drop to 3%, and the total feeder plus branch drop to 5%.

If you run 10 AWG copper wire 150 feet to a 30-amp RV pedestal, the wire will safely handle the 30 amps thermally (using the 60°C column limit). However, at 30 amps over 150 feet, you will experience a voltage drop of roughly 7.7 volts (over 6%). Your RV's air conditioner compressor will struggle to start, draw locked-rotor current, and potentially burn out. To maintain a 3% drop on a 150-foot, 30-amp run, you must upsize to 6 AWG copper, entirely ignoring the thermal ampacity chart in favor of voltage drop mathematics.

AWG Amps FAQ: Long-Tail Questions Answered

How many amps can 12 AWG wire handle on a 20-amp breaker?

12 AWG copper wire is rated for 20 amps in standard residential applications when protected by a 20-amp breaker. While the 75°C column shows 25 amps and the 90°C column shows 30 amps, NEC 240.4(D) strictly caps the overcurrent protection for 12 AWG wire at 20 amps. You cannot put 12 AWG wire on a 25-amp breaker, even if the wire's insulation is technically rated higher.

What size wire do I need for a 50-amp EV charger?

This requires calculating for a continuous load. The NEC defines an EV charger as a continuous load (operating for 3 hours or more), meaning you must size the wire and breaker for 125% of the rated current. A 50-amp charger requires a circuit rated for 62.5 amps (50 × 1.25). Therefore, you need a 70-amp breaker (the next standard size up per 240.4(B) if 62.5 isn't standard, though 60A or 70A are common depending on exact charger specs) and wire rated for at least 62.5 amps. Using the 75°C column, 6 AWG copper THHN (rated 65A) or 4 AWG aluminum (rated 65A) is required. If you are using NM-B (Romex), you must use the 60°C column, which pushes the requirement up to 4 AWG copper (rated 70A).

Can I use 90°C THHN ampacity for my main panel lugs?

Almost never. While the THHN wire inside your walls is rated for 90°C, the lugs on your main breaker panel and your branch breakers are typically rated for 75°C. Per NEC 110.14(C), you must use the 75°C column (or 60°C for smaller circuits/NM-B) to determine your final ampacity and breaker size. The 90°C column is only used as the baseline before applying derating factors for high ambient temperatures or conduit bundling.

Does the ground wire count towards AWG amp derating?

No. When calculating bundling derating factors for conduit fill, you only count current-carrying conductors. Per NEC 310.15(C)(1), equipment grounding conductors (the bare copper or green wire) are not considered current-carrying under normal operating conditions because they only carry current during a fault. Therefore, if you pull two hots, one neutral, and one ground through a conduit, you only count three current-carrying conductors, meaning no bundling derating is required.

Disclaimer: This guide provides NEC-style guidance based on the National Electrical Code. Local Authorities Having Jurisdiction (AHJ) and municipal inspectors have final authority over code compliance in your specific area. Always consult a licensed electrician for service entrance upgrades or complex load calculations.