The allowable ampacity of an 8 AWG depends on the type of conductor (copper, aluminum), thickness of the conductor, and temperature. According to NEC, the 8 AWG amp rating of copper THHN/THWN-2 at 90 °C is 55 Amps. The same goes for copper XHHW/XHHW-2, RHH/RHW-2, and USE-2. 8 AWG copper cable is one of the most popular cables for medium-load applications.

For copper cables only rated for temperatures up to 70 °C, such as RHW, THHW, and XHHW, the AWG 8 wire amp rating is 50 Amps. Finally, the TW/UF copper cables can only handle 40 Amps up to 60 °C. This is because TW and UF insulations are rated for lower temperatures.

These ampacity ratings above are the most accurate for wires used in free air because the air dissipates easier in the air, and there is no insulating effect from the surroundings and heat accommodation from the neighboring cables.

For copper cables in conduit, the amp rating for 8 Awg wire THHN/THWN-2 is approximately 40 Amps, while the ampacity of TW/UF nears 35 Amps.

How Many Amps Can 8 AWG Aluminum Wire Handle?

For aluminum cables, the ampacity of 8 AWG is lower because of the lower copper conductivity. Precisely, it is 45 Amps for THHN/THWN-2, XHHW/XHHW-2, RHH/RHW-2, and USE-2; 40 Amps for RHW, THHW, and XHHW, and 30 Amps for TW/UF. In conduit or raceways, it will be 30-35 Amps for THHN/THWN or XHHW and 25-30 amps for UF insulation.

Common Applications of 8 AWG Cables

8 AWG is one of the most popular wire sizes for medium loads in residential, commercial, and industrial settings. Here are some of the popular applications of cables in this size:

• Branch Circuits:

#8 AWG can be used for larger branch circuits feeding specific high-demand appliances or equipment.

• Subpanels:

This cable is often used to feed subpanels, especially when the distance is not too long and the demand is not exceedingly high.

• Air Conditioning Units:

Due to their high current draw, many central AC units or heat pumps require #8 AWG wire for their circuits.

• Water Heaters:

Some larger electric water heaters, especially tankless ones, use 8 AWG wires.

• Large Motors:

Larger motors, such as those for pumps, might use #8 AWG wire, depending on the motor's current draw and starting amperage.

• Ovens and Ranges:

While many household ovens and ranges require larger cables (like 6 AWG or bigger), some smaller units or models designed for spaces like apartments might be suitable for 8 AWG.

• Hot Tubs and Spas:

Some hot tubs or spas, especially those with multiple heaters or pumps, may require #8 AWG wire for their circuits.

• Service Entrance:

#8 AWG could be used as a service entrance cable in some smaller homes or structures with minimal electrical demand. However, this is less common in modern homes with higher electrical needs.

• Agricultural and Irrigation:

#8 AWG can be used in agricultural applications, such as feeding power to outbuildings or irrigation systems.

• Renewable Energy Installations:

This size wire might be used in solar panel installations or wind turbines, typically for short-distance connections between panels and inverters.

• Grounding:

In some scenarios, #8 AWG wire can be used for grounding or bonding, especially for specific equipment or subpanels.

• Portable Power Applications:

#8 AWG might be found in larger extension cords or power drops in industrial or construction settings.

Popular Types of 8 AWG Wire

Here are some of the popular 8-gauge cables sold by NNC:

• 8 AWG THHN THWN-2 Copper Cable (55 Amps)
• 8 AWG THHN THWN-2 Aluminum Cable (45 Amps)
• 8/2 and 8/3 NM-B Romex (40 Amps)
• 8/2 UF-B  (40 Amps)
• 8/3 Aluminum MC (40-55 Amps, depending on the temperature).
• 8-8-8-8 Aluminum SER Cable ( Up to 45 Amps).