When you search for an 'AWG table PDF,' you are almost always looking for the allowable ampacity chart derived from the National Electrical Code (NEC). Specifically, this is NEC Table 310.16 (formerly 310.15(B)(16) in older code cycles). This table dictates the maximum continuous current a specific wire gauge can carry before its insulation degrades. While you can download official PDFs from the NFPA 70: National Electrical Code portal, simply having the chart is not enough. Misreading the temperature columns or ignoring derating factors is the leading cause of undersized feeders and melted terminations on the jobsite. This guide breaks down exactly how to read the table, which column actually applies to your breaker, and the critical limitations the PDF leaves out.
How to Read the NEC AWG Table PDF
The standard AWG ampacity table is divided into three primary temperature columns for both copper and aluminum conductors: 60°C (140°F), 75°C (167°F), and 90°C (194°F). These numbers represent the maximum temperature rating of the wire's insulation (e.g., TW is 60°C, THHW is 75°C, THHN is 90°C).
Which column applies to your installation? This is where most DIYers and junior apprentices make a critical error. You must follow the 'weakest link' rule. Even if you pull 90°C THHN wire through your walls, the breakers, lugs, and receptacles you terminate that wire into are almost universally rated for a maximum of 75°C. Therefore, you must size your overcurrent protection (breaker) using the 75°C column. The 90°C column is strictly reserved as the starting baseline for calculating derating adjustments, which we will cover below. If you size a breaker using the 90°C column, you risk overheating the breaker's internal bimetallic strip or melting the termination lug long before the breaker trips.
The Master AWG Ampacity Chart (NEC Table 310.16)
Below is the complete data table for the most common residential and light-commercial wire sizes, sourced directly from the 2023 NEC Table 310.16. This assumes an ambient temperature of 30°C (86°F) and not more than three current-carrying conductors in a raceway.
| AWG / kcmil | Copper 60°C | Copper 75°C | Copper 90°C | Aluminum 75°C | Aluminum 90°C |
|---|---|---|---|---|---|
| 14 | 15A* | 20A* | 25A* | - | - |
| 12 | 20A* | 25A* | 30A* | - | - |
| 10 | 30A | 35A | 40A | - | - |
| 8 | 40A | 50A | 55A | 40A | 45A |
| 6 | 55A | 65A | 75A | 50A | 60A |
| 4 | 70A | 85A | 95A | 65A | 75A |
| 3 | 85A | 100A | 115A | 75A | 85A |
| 2 | 95A | 115A | 130A | 90A | 100A |
| 1 | 110A | 130A | 145A | 100A | 115A |
| 1/0 | 125A | 150A | 170A | 120A | 135A |
| 2/0 | 145A | 175A | 195A | 135A | 150A |
| 3/0 | 165A | 200A | 225A | 155A | 170A |
| 4/0 | 195A | 230A | 260A | 180A | 205A |
*Note: NEC 240.4(D) strictly limits overcurrent protection for 14, 12, and 10 AWG copper to 15A, 20A, and 30A respectively, regardless of the higher values shown in the 75°C and 90°C columns.
What the AWG Table Cannot Tell You (Derating & Limits)
An AWG table PDF is a baseline document, not a complete engineering solution. It assumes ideal conditions: an ambient air temperature of 30°C (86°F) and no more than three current-carrying conductors bundled together. When real-world conditions deviate, you must apply correction factors.
How derating rows modify the base value: If you pull four to six current-carrying conductors through a single conduit, NEC Table 310.15(C)(1) requires you to derate the ampacity to 80%. Here is the critical trick: you apply this derating percentage to the 90°C column, not the 75°C column. For example, if you have five 10 AWG THHN copper wires in a conduit, you start with the 90°C base value of 40A. Multiply 40A by 0.80, which equals 32A. Because 32A is still higher than the 30A breaker limit for 10 AWG (per 240.4(D)), the wire is legally compliant. If the derated value drops below your breaker size, you must upsize the wire gauge.
Voltage Drop: The AWG table only tells you the point at which the wire's insulation will melt or degrade. It does not guarantee that 120V will actually reach your load. For long runs (typically over 100 feet), you must calculate voltage drop. The Copper Development Association Wire Sizing Guide recommends keeping voltage drop under 3% for branch circuits. A 12 AWG wire on a 50-foot run carrying 16A is perfectly safe according to the ampacity table, but on a 150-foot run, it will suffer a voltage drop exceeding 5%, causing motors to overheat and lights to dim. The ampacity table will not warn you about this; you must use a voltage drop calculator.
Conduit Fill Capacity: The table ignores physical geometry. You might calculate that three 4 AWG wires are electrically sufficient for a 60A subpanel feeder, but if you try to pull them through a 1/2-inch EMT conduit, you will violate NEC Chapter 9 conduit fill tables and likely jam the wires, damaging the insulation.
AWG Table PDF Frequently Asked Questions
Can I use the 90°C column to size my breaker for a 50A circuit?
No. While 8 AWG THHN wire has a 90°C ampacity of 55A, you cannot put it on a 50A breaker if the breaker lugs are rated for 75°C (which almost all are). At the 75°C column, 8 AWG copper is only rated for 50A. If you used the 90°C column to justify putting 8 AWG on a 60A breaker, the wire would survive, but the breaker's termination lug would overheat and fail. Always terminate based on the lowest temperature rating of any connected component.
How do ambient temperature correction factors modify the AWG table values?
If you are running wire through an attic that reaches 120°F (49°C), the 30°C baseline of the table no longer applies. According to NEC Table 310.15(B)(1), you must multiply the base ampacity by a correction factor. For 90°C wire in a 120°F attic, the correction factor is 0.82. If you are using 6 AWG THHN (base 90°C ampacity of 75A), you multiply 75A by 0.82 to get a derated ampacity of 61.5A. This is still sufficient for a 60A breaker, but if the attic reached 140°F (factor 0.71), the derated value would drop to 53.2A, forcing you to upsize to 4 AWG.
Why does my AWG table PDF show different numbers than my local inspector?
The NEC is a model code, and local Authorities Having Jurisdiction (AHJs) frequently amend it. Some municipalities adopt older versions of the NEC (like the 2017 cycle, which used different table numbering), while others enforce stricter local amendments regarding aluminum wire, specific conduit types, or renewable energy systems. Always verify which code year your local building department enforces before finalizing a wire sizing plan based on a generic PDF downloaded from the internet.
