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8 Wire Amp Rating

If you need a gauge wire for an application that requires high Amps and you want the energy loss to be minimal, you can use an 8 gauge wire. When we talk about 8 gauge wiring, you can see it being majorly used in residential applications.

Although the circuits used in residential areas are generally between 15-20 Amps, the major use of the 8 gauge wire is seen inside the homes. Are you wondering how many Amps can be handled by an 8-gauge wire? This is one of the common doubts, and this article has it all covered.

What is a Wire Gauge?

Wire gauge refers to the wire diameter’s measurement. With this measure, we can know how much electric current can be carried safely by the wire. The wire gauge also tells us about the wire’s electrical resistance and weight.

What is an Ampacity?

Ampacity is a condensed version of “Ampere Capacity”. It indicates the maximum current that can be carried by a conductor without an increase in its temperature rating provided the usage conditions are normal. When the ampacity of a conductor is increased, the resultant current will generate excessive heat. This will cause the insulation materials surrounding it to degrade.

What is the Maximum Current-Carrying Capacity of 8-Gauge Wire?

The maximum current carrying capacity or the ampacity of 8-gauge wire purely depends on the type and thickness of the conductor and the surrounding temperature.

As per NEC or National Electrical Code, the amp rating at 90°C for an 8 AWG copper wire THHN/THWN-2 is 55 Amps. This value remains the same for copper RHH/RHW-2, XHHW/XHHW-2, and USE-2. When it comes to using a copper wire for medium load applications, 8 AWG copper cable remains the first choice. Below are some of the other 8 gauge wire amp ratings at different temperatures.

  • @60°C/140°F: 40 Amps
  • @75°C/167°F: 50 Amps
  • @90°C/194°F: 55 Amps

These ratings are most accurate for copper wires used in an atmosphere of free air. This is because the insulating effect is absent from surroundings, and there is no head build-up from the adjacent cables as well.

When it comes to an 8 AWG aluminum cable, the ampacity value is much lower than that of its copper counterpart. This is because copper has a lower conductivity than aluminum. Below are the ampacity values of an 8 AWG aluminum cable.

  • THHN/THWN-2, RHH/RHW-2, XHHW/XHHW-2, and USE-2: 45 Amps
  • RHW, XHHW, and THHW: 40 Amps
  • TW/UF: 30 Amps

In raceways or conduit,

  • THHN/THWN or XHHW: 30-35 Amps
  • UF insulation: 25 -30 Amps

Applications of an 8-Gauge Wire

8 AWG wires are widely used for medium-load applications in commercial, residential, and industrial settings. A few popular applications of an 8-gauge wire are given below.

  • Subpanels: When the distance involved is not very long, and there are no high demands, an 8-gauge wire is used for feeding the subpanels.
  • Branch Circuits: For high-demand equipment and appliances, a larger branch circuit would be required. The 8 gauge wire can be used in these circuits.
  • Water Heaters: The 8 AWG wires are commonly used in the large tankless water heaters.
  • Air Conditioning Units: Since the AC units draw very high current, they require 8 gauge wires for their circuit.
  • Ranges and Ovens: Most of the ranges and ovens need cables that are 6 AWG or higher. However, smaller units of ranges and ovens specifically designed for apartment and residential spaces may need 8 AWG wires.
  • Large Motors: Large motors, like the ones used for pumps may need 8 gauge wire. This depends on the motor’s starting amperage and the current draw.
  • Service Entrance: 8 gauge wire can be used in the form of service entrance cable in small homes and other similar structures where the electrical demand is minimum.
  • Spas and Hot Tubs: Spas and hot tubs equipped with multiple pumps and heaters may need 8 gauge wire for their circuit.
  • Renewable Energy Installations: This sized wire may be used in wind turbines or solar panel installations where the connection distance between inverters and panels is short.
  • Irrigation and Agricultural: Several agricultural applications require the use of an 8 gauge wire. They can be used in irrigation systems and even to feed electrical power to outbuildings.
  • Portable Power: In construction or industrial settings, where larger extension cords are used, the 8 gauge wire can be helpful.
  • Grounding: A few situations may require the use of 8 gauge wire for grounding or bonding. This is especially true for subpanels and other specific equipment.

8 Wire Amp Rating – FAQs

1. Is #8 wire suitable for a 220-volt dryer?

Ans: Depending on the local electrical codes and current requirements, an 8-gauge wire can be used for a 220-volt dryer. To be sure, you can refer to the manufacturer’s recommendations or you can even reach out to an electrician to estimate the proper wire size to be used.

2. Can 8-gauge wire be used for in-wall installations?

Ans: Yes, an 8-gauge wire can be used for in-wall installations, especially for applications requiring a high current. You need to make sure that the wire is rated for in-wall installations and that it follows all the local building codes.

3. Would 8-gauge wire be suitable for the electrical connection of an electric water heater?

Ans: Generally, the electric water heaters will need wires of larger sizes to deal with the high current draw. To be sure, you can check the specifications of the water heater or even consult an electrician for determining the right wire gauge for the efficient and safe operation of your water heater.

4. Is 8-gauge wire appropriate for installing a ceiling fan?

Ans: No, an 8-gauge wire is way too heavy for use in ceiling fans. Typically, a 14 or 12-gauge wire will be required for ceiling fan installations. This wire size would be sufficient for the power requirements of residential fans.

5. Can 8-gauge wire handle 40 amps?

Ans: Yes, an 8-gauge wire can handle a maximum of 40A. Several electrical cooking appliances, like electric cooktops, require 40A.


Basically, an 8 gauge wire can handle an ampacity of 40A to 55A. The Aluminum versions can handle anywhere from 40A to 45A. As you can see from the above sections, 8 gauge wire has a wide range of applications in commercial and residential buildings. With the help of this article, you will now know where the use of an 8 gauge wire is ideal and where it is not.

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