Aluminum Wire Ampacity Chart

David Smith

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Aluminum Wire Ampacity Chart

Aluminum wires, a cost-effective alternative to copper, dominate electrical applications due to their affordability and lightweight nature, especially in long-distance electrical lines. Understanding the ampacity of aluminum wires is crucial for selecting the right wire size based on temperature conditions. In this guide, we’ll delve into the intricacies of aluminum wire ampacity, exploring key factors and providing practical insights.

aluminium wire
aluminium wire

Ampacity of Aluminum Wires

Let’s kick off with a wire gauge amp chart based on the National Electric Code (NEC). This chart helps determine the maximum current that aluminum wires can safely carry without compromising insulation. Here’s a quick reference:

Wire Size 60⁰C 75⁰C 90⁰C 150⁰C
12 gauge 15A 20A 25A 30A
10 gauge 25A 30A 35A 44A
8 gauge 35A 40A 45A 57A
6 gauge 40A 50A 55A 75A

Note: Ampacity is influenced by wire insulation, and values in the table represent the maximum safe current.

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Aluminum Wire Ampacity Chart Based On Sizing


Let’s kick things off with a breakdown of the Aluminum Wire Ampacity Chart. This chart is your go-to resource for understanding how many amps different aluminum wires can handle at various temperatures.

Aluminum AWG Wire Size Ampacity at 60°C (140°F) Ampacity at 75°C (167°F) Ampacity at 90°C (194°F) Maximum Allowable Amps at 75°C
0000 (4/0) AWG 150 Amps 180 Amps 205 Amps 144 Amps
000 (3/0) AWG 130 Amps 155 Amps 175 Amps 124 Amps
00 (2/0) AWG 115 Amps 135 Amps 150 Amps 108 Amps
0 (1/0) AWG 100 Amps 120 Amps 135 Amps 96 Amps
1 AWG 85 Amps 100 Amps 115 Amps 80 Amps
2 AWG 75 Amps 90 Amps 100 Amps 72 Amps
3 AWG 65 Amps 75 Amps 85 Amps 60 Amps
4 AWG 55 Amps 65 Amps 75 Amps 52 Amps
6 AWG 40 Amps 50 Amps 60 Amps 40 Amps
8 AWG 30 Amps 40 Amps 45 Amps 32 Amps
10 AWG 25 Amps 30 Amps 35 Amps 24 Amps
12 AWG 20 Amps 20 Amps 25 Amps 16 Amps

How To Read Aluminum Wire Amp Rating Chart

Understanding the nuances of the chart is crucial. Here’s a breakdown:

  1. AWG Sizes: Ranging from 4/0 to 12 AWG, each with a specified ampacity.
  2. Kcmil Wires: Larger sizes, like 250 to 2000 kcmil, offer higher capacities, up to 560A.
  3. Interpretation: Locate the AWG wire, find its ampacity, and in the last column, discover the maximum conductivity at 75°C.

Correction or Derating Aluminum Wire Ampacities

aluminium wire
aluminium wire

More Than Three Current-carrying Wires

When using more than three current-carrying conductors, derating becomes essential. Here’s a percentage breakdown based on the number of wires:

Wires Derating (%)
4-6 80
7-9 70
10-20 50

Example: Using four 10-gauge aluminum THHN wires? Derate to 80% for a safe maximum current of 28A (80% of 35A).

Different Ambient Temperature

Adjustments are needed if ambient temperatures deviate from standards. Here’s a correction factor table:

Ambient Temp 60⁰C 75⁰C 90⁰C 150⁰C
10 or less 1.29 1.20 1.15 1.13
11-15 1.22 1.15 1.12 1.11

Example: At 50⁰C, correct 10-gauge THHN wire ampacity by 0.82 for a maximum safe current of 28.7A.


An aluminum wire ampacity chart simplifies wire selection, ensuring safe electrical use. Know your ambient temperature and conductor count to directly use table values for reliable applications.

Frequently Asked Questions

1. How do I choose the right aluminum wire size?

Refer to the ampacity chart based on NEC standards, considering insulation type and ambient temperature.

2. What is derating, and when is it necessary?

Derating adjusts ampacity for factors like the number of wires and ambient temperature, preventing heat accumulation.

3. Can I use the table values directly for all applications?

Yes, if conditions match; otherwise, corrections are needed for a safe application.

4. Why is ampacity crucial in electrical wiring?

Ampacity ensures wires carry current safely without damaging insulation or causing hazards.

5. How does insulation type affect ampacity?

Insulation type dictates the maximum temperature a wire can handle, directly impacting ampacity.

6. Is aluminum wire suitable for all electrical applications?

While cost-effective, aluminum wires may not be suitable for every application; consult the chart for guidance.

7. What happens if I exceed the recommended ampacity?

Exceeding ampacity may lead to insulation damage, posing safety risks; always adhere to recommended values.

8. Can I bury aluminum wires directly without conduit?

For up to three single conductors, burying is possible; follow ambient temperature guidelines for direct burial.

9. How often should I check the ampacity chart?

Check when selecting wires for new installations or modifications; ensure conditions align with the chart.

10. What other factors impact wire selection?

Besides ampacity, consider factors like voltage drop, corrosion resistance, and specific application requirements.

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