Searching for a stranded wire amp chart? Here is the direct answer: for standard THHN/THWN-2 building wire, stranded and solid copper share the exact same ampacity. For standard 60°C residential terminations, the quick-jump ampacities are: 14 AWG = 15A, 12 AWG = 20A, 10 AWG = 30A, 8 AWG = 40A, and 6 AWG = 55A. The misconception that stranded wire carries less current only applies to flexible cords and automotive wire, which use entirely different standards. Below is the complete reference data, derating math, and a decision tree to lock in your exact wire size.

The Master Stranded Wire Amp Chart (NEC Table 310.16)

Before pulling wire, you must understand how to read this chart. The ampacities below are sourced directly from NFPA 70 (National Electrical Code) Table 310.16. This table applies to both solid and stranded copper building wire (like THHN, THWN-2, XHHW) installed in a raceway or conduit. The three temperature columns represent the maximum operating temperature of the wire's insulation. You do not simply pick the highest number; you must match the column to the temperature rating of your circuit's weakest termination point.

Bookmark Quick-Jump: For 90% of standard home branch circuits (receptacles, lighting, basic appliances) terminating on standard 15A or 20A breakers, use the 60°C column for your final breaker sizing, even if your wire insulation is rated for 90°C.
Table 1: Copper Building Wire Ampacities (Source: NEC Table 310.16, 30°C Ambient, up to 3 current-carrying conductors)
AWG / kcmil 60°C (140°F) Column 75°C (167°F) Column 90°C (194°F) Column
14 AWG15A20A25A
12 AWG20A25A30A
10 AWG30A35A40A
8 AWG40A50A55A
6 AWG55A65A75A
4 AWG70A85A95A
3 AWG85A100A115A
2 AWG95A115A130A
1 AWG110A130A145A
1/0 AWG125A150A170A
2/0 AWG145A175A195A
3/0 AWG165A200A225A
4/0 AWG195A230A260A

Which Temperature Column Actually Applies to Your Install?

The most common mistake DIYers make when reading a stranded wire amp chart is looking at the 90°C column because THHN wire is rated for 90°C. You cannot use the 90°C column to size your breaker. Under NEC 110.14(C), the ampacity of your circuit is limited by the lowest temperature rating of any connected component.

  • Use the 60°C Column when: You are wiring standard 15A or 20A residential receptacles, older breakers, or any equipment not explicitly marked with a higher temperature rating. This is the default safe harbor for general home branch circuits.
  • Use the 75°C Column when: You are terminating on modern, explicitly marked 75°C breakers (most standard Square D, Eaton, and Siemens breakers above 30A), subpanel lugs, or heavy-duty appliances like electric ranges and dryers.
  • Use the 90°C Column ONLY for: Calculating derating adjustments (see below) or determining the absolute thermal limit of the wire before it hits the termination. The final ampacity after derating must still be protected by a breaker sized to the 60°C or 75°C column.

Derating: How Bundle Size and Ambient Heat Modify Base Values

The base values in the chart above assume you have no more than three current-carrying conductors in a conduit and an ambient temperature of 30°C (86°F). If you bundle multiple circuits together in a single conduit, the wires heat each other up. You must apply NEC 310.15(C)(1) adjustment factors to the 90°C column base value to find your new allowable ampacity.

Table 2: Adjustment Factors for More Than Three Current-Carrying Conductors
Number of Conductors Adjustment Factor Example: Four 12 AWG THHN in Conduit
4 - 680%30A (90°C base) × 0.80 = 24A (Safe for 20A breaker)
7 - 970%30A (90°C base) × 0.70 = 21A (Safe for 20A breaker)
10 - 2050%30A (90°C base) × 0.50 = 15A (Must downsize breaker to 15A)
21 - 3045%30A (90°C base) × 0.45 = 13.5A (Requires 10 AWG wire upgrade)
Neutral and Ground Counting: In a standard multi-wire branch circuit (MWBC) or single-phase 120/240V circuit, the equipment grounding conductor does not count as a current-carrying conductor. However, if you are running 3-phase circuits or circuits with heavy non-linear harmonic loads (like LED drivers or VFDs), the neutral does count, which will push you into a lower derating tier.

What the Chart Cannot Tell You: Flexible Wire and Voltage Drop

NEC Table 310.16 is strictly for fixed building wire. It will give you dangerously incorrect numbers if you apply it to the following scenarios:

  1. Flexible Stranded Cords (SOOW, SJT, Welding Cable): These wires use much finer stranding and different rubber/PVC insulation. They dissipate heat differently and are subject to physical abuse. You must use NEC Table 400.5 for flexible cords. For example, a 12 AWG SOOW cord is only rated for 21A (75°C), not the 25A listed in 310.16.
  2. Automotive and Marine Battery Cables (SAE J1128 / ABYC E-11): 12V DC systems require massive wire sizes not because of thermal ampacity, but because of voltage drop. A 4 AWG stranded automotive wire might handle 100A thermally for a short run, but over 15 feet to a trolling motor, the voltage drop will starve the motor.
  3. Voltage Drop in Building Wire: The amp chart only tells you the wire's thermal limit before the insulation melts. It does not guarantee the voltage will reach the load. For runs over 50 feet, always calculate voltage drop (aim for <3% on branch circuits). You will frequently need to upsize your stranded wire one or two AWG sizes larger than the amp chart strictly requires to maintain proper voltage at the receptacle.

Decision Tree: Pick Your Exact Wire Size and Type

Stop guessing. Follow this if-then path to terminate your search and select the exact wire for your project.

Table 3: Wire Selection Decision Matrix
Application Scenario Wire Type Required Governing Standard Concrete Pick / Action
Standard indoor home branch circuit (120V/240V receptacles, lighting, pulled in conduit) THHN / THWN-2 Stranded Copper NEC 310.16 Use 12 AWG for 20A breakers; 10 AWG for 30A breakers. Size breaker using the 60°C column.
Subpanel feeder (e.g., 60A or 100A detached garage subpanel) XHHW-2 or THHN Stranded Copper NEC 310.16 (75°C col) For 60A, pick 6 AWG (if terminations are 75°C rated) or 4 AWG (if 60°C). Calculate voltage drop if over 50ft.
Appliance power cord (e.g., custom extension cord for a table saw or generator) SOOW or SJTW Flexible Stranded NEC 400.5 For a 15A saw, pick 14 AWG SOOW. For a 20A load, pick 12 AWG SOOW. Do not use THHN.
12V/24V DC Solar or Battery bank (Inverter connections, charge controller to battery) Welding Cable or Fine-Strand RHW NEC 310.16 / ABYC E-11 Size for <2% voltage drop, not just ampacity. For a 2000W inverter (160A+ at 12V), pick 2/0 AWG welding cable.

Final Rule of Thumb: If you are pulling wire through PVC conduit in your walls, buy standard THHN/THWN-2 stranded copper and use the 60°C column of Table 310.16 to match your breaker. If the wire needs to bend repeatedly, plug into a wall, or sit outside in the weather, switch to an Article 400 flexible cord and derate your ampacity expectations by at least 15%.