The base ampacity for 2 AWG wire depends on the conductor material and insulation temperature rating. According to NEC Table 310.16, 2 AWG copper wire is rated for 115A (60°C column), 130A (75°C column), and 145A (90°C column). For 2 AWG aluminum wire, the ratings are 90A, 100A, and 115A, respectively. In most modern residential installations with 75°C rated breakers, you will use the 75°C column, making 2 AWG copper good for 130 amps and 2 AWG aluminum good for 100 amps.
The 2 AWG Wire Ampacity Reference Table (NEC 310.16)
Before pulling wire, you need to know how to read the National Electrical Code (NEC) ampacity tables. The rows represent the American Wire Gauge (AWG) size and the base material (Copper or Aluminum). The columns represent the maximum operating temperature of the wire's insulation. The intersection gives you the maximum continuous current the wire can carry under standard conditions (an ambient temperature of 30°C / 86°F and no more than three current-carrying conductors bundled together).
Below is the data-dense reference chart for 2 AWG and its immediate neighboring sizes, sourced directly from NFPA 70 (NEC) Table 310.16. Bookmark this section for quick job-site lookups.
| AWG Size | Material | 60°C (140°F) TW, UF |
75°C (167°F) THW, THWN, XHHW |
90°C (194°F) THHN, THWN-2, XHHW-2 |
|---|---|---|---|---|
| 3 AWG | Copper | 100A | 115A | 130A |
| 2 AWG | Copper | 115A | 130A | 145A |
| 1 AWG | Copper | 130A | 145A | 165A |
| 1/0 AWG | Copper | 150A | 170A | 195A |
| 3 AWG | Aluminum | 75A | 90A | 100A |
| 2 AWG | Aluminum | 90A | 100A | 115A |
| 1 AWG | Aluminum | 100A | 115A | 130A |
| 1/0 AWG | Aluminum | 120A | 135A | 155A |
Source: NFPA 70 National Electrical Code, Table 310.16. Values assume not more than three current-carrying conductors in a raceway, cable, or earth, and an ambient temperature of 30°C (86°F).
Which Temperature Column Applies to Your Installation?
A common mistake on the bench and in the panel is defaulting to the 90°C column simply because modern THHN/THWN-2 wire is printed with that rating on the jacket. You cannot always use the 90°C column. The NEC enforces a strict 'weakest link' rule under Article 110.14(C): the ampacity of your circuit is limited by the lowest temperature rating of any connected termination, device, or conductor in the entire run.
The 60°C Column
You must use the 60°C column (115A for Copper, 90A for Aluminum) if you are terminating into older equipment, specific types of NM-B (Romex) cable, or devices explicitly marked for 60°C only. While modern NM-B uses 90°C rated THHN conductors inside the sheath, NEC 334.80 mandates that the ampacity of NM-B cable be determined by the 60°C column due to the thermal limitations of the outer PVC jacket.
The 75°C Column (The Residential Standard)
For 95% of modern residential and light commercial subpanel feeders, you will use the 75°C column. Most modern molded-case circuit breakers, lugs, and disconnect switches are tested and rated for 75°C terminations. Therefore, a 2 AWG aluminum SER (Service Entrance) cable feeding a 100A subpanel is perfectly code-compliant because its 75°C ampacity is exactly 100A. If you are using 2 AWG copper THWN in conduit to feed a 125A breaker, the 75°C rating of 130A safely covers the load.
The 90°C Column
The 90°C column (145A for Copper, 115A for Aluminum) is rarely used to determine the final breaker size. Instead, it serves as the starting baseline for derating calculations (explained below) and for equipment specifically listed and marked for 90°C terminations, which is generally reserved for heavy industrial switchgear.
How Derating Modifies Your Base 2 AWG Ampacity
The values in the table above assume ideal conditions: an ambient air temperature of 86°F (30°C) and no more than three current-carrying conductors bundled in a single conduit. When real-world conditions deviate from this baseline, you must apply derating (adjustment) factors. You always apply these factors to the 90°C column, even if your final termination limits you to the 75°C column. This is a massive advantage of using 90°C rated wire like THHN.
Let's walk through a concrete, data-dense example. Imagine you are pulling four current-carrying conductors (two hots, a neutral carrying unbalanced load, and a ground which doesn't count) through an attic conduit where the ambient temperature hits 110°F (43°C).
- Start with the 90°C base: 2 AWG Copper THHN = 145A.
- Ambient Temperature Correction: According to NEC Table 310.15(B)(2)(a), the correction factor for 90°C wire at 110°F (43°C) is 0.91.
145A × 0.91 = 131.95A. - Bundling Adjustment: According to NEC Table 310.15(B)(3)(a), 4 to 6 current-carrying conductors require an 80% adjustment factor.
131.95A × 0.80 = 105.56A.
Your final derated ampacity for that 2 AWG copper wire is 105.56A. You must now size your overcurrent protective device (breaker) at or below this number. A standard 100A breaker is required; you cannot use a 110A or 125A breaker for this specific run, despite the wire being 2 AWG.
If you had mistakenly started your math from the 75°C column (130A), your final derated value would have been 94.8A, forcing you to upsize to 1 AWG or drop to an 80A or 90A breaker. This illustrates exactly why the 90°C column exists: it provides a thermal buffer for derating.
What the Ampacity Table Cannot Tell You
While NEC Table 310.16 is the bible for thermal limits and fire prevention, it does not account for power quality or mechanical failure modes. Relying solely on ampacity charts will leave you blind to three critical engineering realities.
1. Voltage Drop Limitations
Ampacity tables tell you how much current a wire can carry before the insulation melts. They do not tell you how much voltage will be lost over distance due to the resistance of the copper or aluminum. NEC 310.15(B) does not strictly enforce voltage drop limits (it's an Informational Note, not a mandatory rule in most jurisdictions), but standard engineering practice dictates a maximum 3% drop for branch circuits and 5% for the total feeder + branch combined.
For example, pushing 100A through 100 feet of 2 AWG Copper on a 120V circuit results in a voltage drop of roughly 3.88V (about 3.2%). If that same 2 AWG wire is running 240V, the percentage drop halves to 1.6%, which is excellent. However, if you are running a 100A load 250 feet away, 2 AWG will yield an unacceptable 8% drop, and you will need to upsize to 1/0 or 2/0 AWG purely for voltage regulation, even though the 2 AWG wire won't overheat. Always cross-reference with a voltage drop calculator for long runs.
2. Short-Circuit Withstand Ratings
Ampacity is about continuous, steady-state heat. It does not tell you what happens when a dead short occurs and 10,000 amps suddenly surge through the wire before the breaker's magnetic trip clears the fault in 16 milliseconds. The thermal mass and specific insulation type dictate whether the wire survives the fault or vaporizes. While 2 AWG is generally robust enough for standard residential 10kAIC or 22kAIC breakers, industrial applications with high available fault currents require checking the specific short-circuit withstand data provided by the cable manufacturer.
3. Physical Pulling Tension
Finally, the table says nothing about the mechanical stress of installation. 2 AWG wire, especially copper, is stiff and heavy. When pulling through conduit with multiple bends, exceeding the maximum pulling tension can stretch the copper, permanently altering its crystalline structure, increasing its resistance, and creating a localized hot spot that won't show up on an ampacity chart. Always use appropriate wire pulling lubricant and a pulling grip rated for the specific gauge when navigating long or complex conduit runs.
