Are you thinking about installing an 8-gauge wire? You cannot proceed without first comparing the capacity of the cables to the applications. The last thing you want is to melt the wires because you exceeded their amp rating. But what is the amp rating of 8-gauge wire?
How many Amps Can 8 Gauge Wire Carry?
According to NEC, 8-gauge copper wire can handle a maximum of 40-55 amps while 8 gauge aluminum wire can handle a maximum of 30-45 Amps.
8 Gauge Wire Amp Rating
| Copper | Aluminum | |||||
| Wire Gauge Size | 60˚C NM-B, UF-B | 75˚C THW, THWN, SE, USE, XHHW | 90˚C THWN-2, THHN, XHHW-2, USE-2 | 60˚C NM-B, UF-B | 75˚C THW, THWN, SE, USE, XHHW | 90˚C XHHW-2, THHN, THWN-2 |
| 8AWG | 40 | 50 | 55 | 30 | 40 | 45 |
8 gauge wire can withstand 40 – 55 amps. However, the chances of an 8AWG cable safely carrying 55 amps are low. Though, non-metallic cables can only withstand 40 amps. That figure jumps to 55 amps if you use copper wires. But then it falls to 30-45A for aluminium wires.
You must learn to identify the amperage of 8AWG wire based on factors like the material and distance. Otherwise, the wrong application will melt the wires and start a fire.
In this case, the wrong application is any task that forces more than 55 amps of current to pass through the 8AWG conductor. In other words, you can afford to pair appliances with a lower amperage with 8AWG wire.
Admittedly, using 8AWG conductors for 30A applications wouldn’t make sense when you can use 10AWG wire. After all, 8AWG is thicker and more expensive. This shouldn’t stop you from using 8AWG cables for circuits with lower amp ratings.
Consumers use 8AWG cables on 30A circuits as a way of future-proofing their homes. They can place a larger load on the circuit down the line knowing that the wiring can take it.
Regardless of what you choose, you should be fine so long as you remember to keep appliances and circuits above 55 amps away from your 8-gauge cables. 60 and 100A circuits are too powerful. They will overwhelm the wires.
Let’s look at a table to check if this wire can handle these amps or not.
| Amps | 8-Gauge Wire |
| 30A | Handle |
| 40A | Handle |
| 50A | Handle |
| 60A | Can’t Handle |
| 100A | Can’t Handle |
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- 30 Amp Breaker Wire Size
How Far Can I Run 8-Gauge Wire?
You can run 8 AWG copper wires for 62 feet in a 120V circuit,124 feet in a 240V circuit and 249 feet in 480V. Their objective is to keep the maximum voltage drop at 3 per cent or less. While you can run 8 AWG aluminum wires for 53 feet in a 120V circuit, 106 feet in 240V and 213 feet for 480V
8AWG Copper Wire
| Voltage | Max Distance |
| 120V | 62 ft |
| 240V | 124 ft |
| 480V | 249 ft |
8AWG Aluminum Wire
| Voltage | Max Distance |
| 120V | 53 ft |
| 240V | 106 ft |
| 480V | 213 ft |
The voltage drop is a significant threat to circuits and appliances. If the wire is too long, the voltage drop will increase because of a spike in the resistance. In the case of 8AWG conductors, if the wire is too long, you have to increase the size to 6 or 4AWG to prevent the voltage drop from rising.
However, if your objective is to use 8AWG wires, restrict the length to 62 feet (120V) and 124 feet (240V).
Does Distance Affect Its Amp Rating?
The distance doesn’t affect the amp rating, not directly. If the length increases, the resistance will also rise, elevating the amount of heat generated. The wire is more likely to overheat.
More importantly, the voltage drop may prevent the wire from meeting the electrical requirements of the appliance to which it is connected. In some cases, the machine will draw more current than usual to compensate for the voltage drop, making overheating a more significant concern.
But even with all these considerations, the wire’s amp rating won’t change.
An 8AWG cable will carry 40-55A regardless of whether the distance is 10 feet or 100 feet.
For safety, go to the next largest size whenever the length exceeds 100 feet. But technically speaking, the amp rating won’t change.
Does Voltage Affect Its Amps?
The voltage affects the amperage. The voltage is comparable to the force that pushes water through a pipe. The amperage looks at the current the voltage is pushing through a conductor. Therefore, the amperage has to increase as the voltage increases.
Power Probe has published equations that explain the relationship between resistance, amperage, and voltage.
From what they’ve seen, the amps will increase with the voltage if the resistance stays the same. On the other hand, the amperage and resistance are inversely proportional to one another.
This is easier to understand if you remember that the resistance opposes the flow of electricity. Therefore, if the resistance has increased, the current has to decrease.
How many Amps can 8-Gauge Wire Handle At 12 Volts?
8AWG wire can handle 40 to 55A at 12 volts. The amount of electricity the wire can take does not change regardless of the voltage.
How Many Amps Can 8-Gauge Wire Handle At 220 Volts?
8-gauge wire can handle 40 to 55 amps at 220V. The voltage has no bearing on the gauge of a wire or the volume of electricity it can take. Where the gauge and amperage are concerned, the voltage only matters in high-voltage applications. High voltage applications involve ratings as high as 2kV.
How Many Amps Can 8-Gauge Wire Handle At 240 Volts?
8AWG wire can handle 40 to 55 amps at 240 volts. The voltage doesn’t matter. The voltage affects the insulation and vice versa. However, it won’t change the amount of current the wire can carry.
When you look at any table showing the different gauges and their corresponding amp ratings, you will notice that they rarely mention the voltage, if ever. This tells you that the voltage doesn’t affect your choice regarding the wire size.
What Does NEC Say About It?
NEC expect 8AWG cables to transmit 40 amps successfully.
As this USA Wire-Cable table shows, the NEC agrees. However, don’t expect the NEC to apply in every single situation. Most regions have adopted the NEC’s rules and regulations.
But they don’t have to. If your local code has rules that differ from the NEC, your local code’s regulations supersede the NEC. Therefore, before you act, take the time to find out what your local code has to say about 8-gauge wires and their corresponding amp rating.
Does Material (Copper/Aluminum) Affect Amp Rating?
The material affects the amp rating. Aluminum has lower conductivity than copper. For that reason, aluminum conductors have a lower carrying capacity, resulting in an increased voltage drop.
GSES prefers copper to aluminum cables. They admit that aluminum is more attractive because it is cheaper. However, an 8AWG copper wire has a higher amp rating than an 8AWG aluminum cable.
Budget-constrained people are more likely to buy aluminum because of financial considerations. Copper is a great conductor for small projects. But for large projects that require long cables, you can save a lot of money by using aluminum.
You must use a higher gauge to replicate the carrying capacity of copper.
For instance, if you cannot afford 8AWG copper wire, you are better off using 6AWG or even 4AWG aluminum wire. 8AWG aluminum conductors are a poor substitute for 8-gauge copper.
How To Calculate Exact Amps For 8-Gauge Wire?
Fortunately, you don’t have to calculate the exact amps for 8-gauge wire. The NEC has already done all the difficult work for you. They have a table showing the various wire sizes and their associated amp ratings. They also present the wire size in mm.
If you want to know the amperage of 8AWG wire, get an NEC table and look for the column with 8AWG. Look at the corresponding rows to find the amperage. The NEC doesn’t expect the layperson to perform the complex calculations required to identify the amp rating.
What Is 8-Gauge Wire Used For?
8AWG cables are used for electric cooking appliances like a double oven range. 8AWG conductors can handle 40 to 55 amps, which is a lot of power. This is why the wire size is perfect for your kitchen. You can trust it to accommodate the electrical needs of your kitchen’s heavy-duty appliances.
How To Tell 8 Gauge Wire?
- According to Hunker, you can just look at the cable’s jacket. It has all the information you need, including the gauge of the wire.
- Wikihow has a more drastic solution. They want you to cut the wire (Using Wire Cutters). The goal is to remove insulation to measure the diameter of the cross-section of the conductor. You get the gauge by dividing the diameter by ‘.46,’ taking the logarithm of the result, and then dividing that result by ‘-.050305.’ Once you subtract three, you will get the gauge.
- Contact the manufacturer. They will tell you the gauge of their product.
How Many Watts Can 8-Gauge Wire Handle?
8AWG wire can handle 40 amps, you can find the wattage by multiplying 40 amps by 120V, which gives you 4,800 watts. If you have a 240V circuit, multiply 40 amps by 240 volts, which gives you 9,600 watts.
Finding the watts an 8AWG wire can handle is not difficult. To find the wattage, you should multiply the amperage by the voltage.
120V
| Gauge | Amperage | Wattage |
| 18 | 7A | 840W |
| 16 | 10A | 1,200W |
| 14 | 15A | 1,800W |
| 15 | 20A | 2,400W |
| 10 | 30A | 3,600W |
| 8 | 40A | 4,800W |
| 6 | 55A | 6,600W |
| 4 | 70A | 8,400W |
| 2 | 95A | 11,400W |
240V
| Gauge | Amperage | Wattage |
| 18 | 7A | 1,680W |
| 16 | 10A | 2,400W |
| 14 | 15A | 3,600W |
| 15 | 20A | 4,800W |
| 10 | 30A | 7,200W |
| 8 | 40A | 9,600W |
| 6 | 55A | 13,200W |
| 4 | 70A | 16,800W |
| 2 | 95 | 22,800W |
An 8AWG wire that can withstand 4,800 watts can easily handle appliances and circuits of 500W, 600W, 1000W, and 1200W.
Make sure you consider the voltage when calculating the wattage. The voltage will affect the wattage.
If you can’t be bothered to perform these calculations yourself, you can use resources like Inch Calculator that can do the math for you. But you must enter the current in amps and voltage beforehand.
People rarely compare the wattage to the gauge. Most tables compare the gauge to amperage. They expect consumers to change the wattage to amperage if they need to determine whether or not a particular gauge is suitable for a specific application.
Can You Use 8-Gauge Wire On A 20,30,40,50 Amp Breaker?
You can use 8-gauge wire on a 20,30,40 and 50-amp breaker. It will only be a problem if it exceeds 55 Amps.
8-Gauge Automotive/Stranded Wire Rating
8-gauge copper wire can handle 55 amps (90 degrees C).