When you search for an "AWG chart PDF," you are actually looking for the data codified in NEC Table 310.16 (formerly 310.15(B)(16)). This table is the absolute authority for determining the allowable ampacity of insulated conductors rated up to 2000 volts. The direct answer for standard residential copper branch circuits is: 14 AWG is 15A, 12 AWG is 20A, and 10 AWG is 30A. However, those baseline numbers assume specific temperature columns and installation conditions that dictate whether your wire will safely carry the load or melt the insulation.
How to Read the NEC 310.16 AWG Chart (and Which Column Applies)
The AWG ampacity chart is divided into three primary temperature columns: 60°C, 75°C, and 90°C. These columns correspond to the thermal rating of the wire's insulation, not the ambient temperature of the room.
- 60°C Column: Applies to older insulation types (TW), non-metallic sheathed cable (NM-B / Romex), and underground feeder (UF-B).
- 75°C Column: Applies to THHW, THWN, and XHHW. Most modern commercial terminations and breakers are rated for at least 75°C.
- 90°C Column: Applies to THHN, THWN-2, and XHHW-2. This is the standard wire pulled in conduit today.
The Master AWG Ampacity Chart (Copper & Aluminum)
Below is the complete reference data derived from the NFPA 70: National Electrical Code (NEC) Table 310.16. Use the quick-jump links to find the most commonly queried residential and commercial sizes.
Quick Jump: 14 AWG | 12 AWG | 10 AWG | 6 AWG | 2 AWG
| AWG / kcmil | Copper 60°C | Copper 75°C | Copper 90°C | Aluminum 75°C | Aluminum 90°C |
|---|---|---|---|---|---|
| 14 | 15 | 20 | 25 | — | — |
| 12 | 20 | 25 | 30 | — | — |
| 10 | 30 | 35 | 40 | — | — |
| 8 | 40 | 50 | 55 | 40 | 45 |
| 6 | 55 | 65 | 75 | 50 | 60 |
| 4 | 70 | 85 | 95 | 65 | 75 |
| 2 | 95 | 115 | 130 | 90 | 100 |
| 1/0 | 125 | 150 | 170 | 120 | 135 |
| 2/0 | 145 | 175 | 195 | 135 | 150 |
| 3/0 | 165 | 200 | 225 | 155 | 175 |
| 4/0 | 195 | 230 | 260 | 180 | 205 |
Applying Derating Factors to Your Base Ampacity
The most common mistake DIYers and junior apprentices make is assuming the ampacity in the chart is a fixed, unchangeable number. In reality, Table 310.16 assumes exactly three current-carrying conductors in a raceway and an ambient temperature of 30°C (86°F). When your installation deviates from this, you must apply derating factors found in NEC 310.15.
This is where the 90°C column earns its keep. While you cannot use the 90°C ampacity for final breaker sizing on standard 75°C terminations, you can use it as your starting baseline for derating calculations before checking it against the termination limit.
Worked Example: Bundled Conductors in EMT
Imagine you are pulling four current-carrying 12 AWG THHN (90°C) wires through a single EMT conduit to feed a multi-wire branch circuit or a 240V appliance with a neutral.
- Find Base Ampacity: 12 AWG in the 90°C column is 30A.
- Apply Bundling Derating: Per NEC Table 310.15(C)(1), 4 to 6 current-carrying conductors require an 80% adjustment factor.
- Calculate Adjusted Ampacity: 30A × 0.80 = 24A.
- Verify Against Termination: Your breaker is rated 75°C. The 75°C column for 12 AWG is 25A. Since your derated value (24A) is less than the termination limit (25A), the final allowable ampacity is 24A.
Because 24A is greater than your required 20A circuit load, 12 AWG THHN is perfectly legal and safe here. If you had attempted this same calculation using NM-B cable (which is strictly limited to the 60°C column, baseline 20A), the 80% derating would drop your capacity to 16A, forcing you to upsize to 10 AWG.
What the AWG Chart Cannot Tell You
While an AWG chart PDF is essential for preventing wire insulation from melting due to overcurrent, it is blind to three critical physical realities of electrical design. Relying solely on Table 310.16 will lead to failed inspections or poorly performing circuits if you ignore the following:
1. Voltage Drop Over Distance
Table 310.16 assumes the wire is infinitely short. In reality, copper has resistance. NEC 310.15(B) Informational Note recommends a maximum 3% voltage drop for branch circuits and 5% total for feeder and branch combined. If you are running a 12 AWG circuit 150 feet to a detached garage for a 15A table saw, the wire won't overheat, but the saw motor will see only 110V under load, causing it to overheat and stall. For long runs, you must consult NEC Chapter 9, Table 8 for exact ohms-per-thousand-feet and upsize your wire accordingly.
2. Conduit Fill Capacity
The ampacity chart tells you how much current a wire can handle, but not how many wires physically fit inside a pipe. Overstuffing a conduit prevents heat dissipation and makes pulling impossible without damaging the insulation. You must cross-reference your wire gauge and insulation type (THHN is thinner than XHHW) against NEC Chapter 9, Table 1 to determine the maximum percentage of conduit cross-sectional area you can occupy (typically 40% for three or more wires).
3. Short-Circuit Withstand
Ampacity is about continuous thermal loading. It does not tell you if a wire can survive the massive magnetic and thermal forces of a 10,000-amp short circuit for the 2 cycles it takes a breaker to trip. For standard residential branch circuits, the AWG sizes in the chart inherently handle available fault currents. However, for large service entrance conductors (like 4/0 or 250 kcmil aluminum) near high-capacity utility transformers, engineers must verify short-circuit withstand ratings to ensure the wire doesn't vaporize before the main breaker clears the fault.
For deeper guidance on termination provisions and specific derating scenarios, refer to Mike Holt's NEC code breakdowns or your local Authority Having Jurisdiction (AHJ), as local amendments can supersede baseline NEC tables.
