Homeowners rarely buy 1/0 wire. That thickness doesn’t serve a purpose in the conventional applications you find in residential settings. If you’re toying with the idea of buying 1/0 AWG wiring, you should take a moment to identify the number of amps it carries. Otherwise, you may pair the gauge with the wrong application.
How Many Amps can 1/0 Wire Carry?
1/0 Gauge copper wire carries 125A while Aluminum wire carries 100A.
1/0 Gauge Wire Amps 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 TW, UF | 75˚C THW, THWN, SE, USE, XHHW | 90˚C XHHW-2, THHN, THWN-2 |
| 1/0AWG | 125 | 150 | 170 | 100 | 120 | 135 |
People use different units to measure the thickness. AWG is the easiest to interpret. But if you prefer more precise measurements, 1/0 has a diameter of 0.3249 inches (8.252 mm or 53.5 mm2).
Also, you shouldn’t confuse 1/0AWG with 1 AWG. Many people use ‘1 AWG’ and ‘1/0 AWG’ interchangeably. They think that 1AWG is the smallest size on the market, but that couldn’t be further from the truth.
1/0AWG is one size thicker than 1 AWG. Some people call it ‘0 AWG.’ The next size after that is 2/0. If you look at any table that shows the various gauges and their ampacities, you will notice that the wire size continues to increase beyond 0AWG.
Eventually, the unit of measurement switches from AWG to kcmil to simplify the process of quantifying the largest cables. As far as the ampacity is concerned, 1/0 AWG can transmit 125 – 170 amps. The exact ampacity will vary depending on factors like the material and temperature.
This is why many homeowners consult professional contractors before selecting a wire size. They know that 1/0 AWG might be too thick or too thin for some applications depending on the ambient temperature, material, and distance.
And unfortunately, the layperson doesn’t have the knowledge or experience they need to select the appropriate ampacity once you introduce additional variables.
They don’t understand how the setting affects the ampacity. Some of them expect the wire’s current carrying capacity to change in response to these elements, which is not the case.
Many homeowners won’t even remember to take these factors into consideration. They think 1/0 wires are too thick to pose a threat to their well-being. Therefore, they don’t see the point in fretting over the variables that affect the conductor’s current carrying capacity.
But that is a mistake. Yes, 1/0AWG cables are very thick. However, that doesn’t mean they can accommodate every application you encounter. Most tables expect these conductors to transmit a maximum of 170 amps safely. What happens when you expose 1/0 AWG to 250 amps?
You can easily start a fire. As you can see, electrical wiring is complicated, and you can’t afford to make a mistake. Therefore, if you’re uncertain about the suitability of 1/0AWG wiring for your application, consult a licensed expert.
What Does NEC Say About It?
According to NEC, 1/0 AWG carry 125A at 60 degrees C (Copper), 150A at 75 degrees C (Copper), 170A at 90 degrees C (Copper), 100A at 60 degrees C (Aluminum), 120A at 75 degrees C (Aluminum), and 135A at 90 degrees C (Aluminum).
You determine a wire’s ampacity by looking at the various tables on the internet, and most of those tables get their information from the NEC. Therefore, you might as well skip them all.
Get your information directly from the source. You don’t need to calculate the ampacity. The NEC’s experts already did the difficult work for you.
Use of 1/0 Gauge Wire
Many laypeople are tempted to use 1/0AWG for heavy-duty applications like welding, but only because they have confused 1/0AWG with 1 AWG. But 1/0AWG is different from 1AWG. The wire size is much thicker.
Contractors pair the so-called 0 wire with large 12V and 24V batteries, not to mention audio speakers. It can also work with welding tools and various 110V/120V devices with significant electrical demands.
1/0 Gauge Wire VS Volts – Does It Affect Amps?
I don’t want you to consider the volts when assessing the suitability of 1/0AWG. The voltage influences the type and quality of insulation.
| Voltage | Amps |
| 12 V | 125A |
| 24 V | 125A |
| 120 V | 125A |
| 240 V | 125A |
The insulation matters because it prevents sparks from jumping between conductors. But this consideration doesn’t matter to consumers in residential settings because the voltage homeowners encounter is within the limits of a 1/0 AWG cable’s insulation.
A contractor can recommend stronger insulation if you think you need it, especially in scenarios where arcing keeps happening. A licensed electrician can identify cables with the appropriate insulation.
You shouldn’t downplay arcing. Those sparks can start fires by melting the insulation. Although, many homeowners rarely consider the dangers of arcing. The type and quality of insulation they use are based on the setting.
For instance, they will arm outdoor or underground conductors with the strongest possible insulation to protect against harsh elements such as direct sunlight, pests, and extreme temperatures that expedite wear and tear.
1/0 Gauge Wire VS Distance – Does It Affect Amps?
The distance affects the amps, but not directly. The wire’s ampacity cannot change. In a way, the amps are set in stone. So, what happens when the distance increases? The resistance rises. You don’t want the resistance to increase because conductors with high resistance generate more heat when they transmit electricity.
For Copper Wire,
Single Phase
| Voltage | Amp | Voltage Drop | Max Distance |
| 120 | 125 | 3% | 135 ft |
| 240 | 125 | 3% | 271 ft |
| 480 | 125 | 3% | 543 ft |
Three Phase
| Voltage | Amp | Voltage Drop | Distance |
| 120 | 125 | 3% | 156 ft |
| 240 | 125 | 3% | 313 ft |
| 480 | 125 | 3% | 627 ft |
But the biggest worry is the voltage drop, which increases as a consequence of high resistance.
The voltage drop affects the power the appliance at the end of the wire receives. In other words, if the voltage drop is too high, the device may stop working because it cannot access the electricity it needs.
What does this mean for the amps? A wire’s ampacity won’t change because the length has increased. However, a considerable distance will force consumers to attach appliances with lower amp ratings because they want to limit the voltage drop.
In other words, even though the cable can accommodate 150A, a contractor may prioritize 80A devices because a 150A load is more likely to overwhelm the 1/0AWG conductors because of the significant distances involved.
Again, the ampacity won’t change. Instead, the contractor will make a deliberate decision to expose the wire to a smaller load because they want to limit the voltage drop and heat generated.
1/0 Wire VS Material (Aluminum VS Copper) – Does It Affect Amps?
Have you ever stopped to consider the material your electrical wires use? The last time you tried to buy cables, you probably noticed that aluminum was cheaper than copper.
However, you must have realized that many of the cables in your home use copper conductors. What does that mean? Is copper better than aluminum? For many contractors, conductivity is the most important consideration.
Copper has a greater conductivity than aluminum. It can transmit more current than aluminum without overheating. That last bit is critical.You can funnel as much current as you want through any conductor you encounter. But if you exceed the wire’s capacity, the conductors will overheat.
The amps cannot exceed the wire’s rating. Therefore, it is not that difficult to understand why many contractors prioritize copper. Copper can transmit more power than aluminum without starting a fire.
The amp rating of 1/0AWG changes with the material. Aluminum conductors carry 120A at 75 degrees C, while their copper counterparts can accommodate as much as 150 amps at the same temperature rating.
The material is one of the few variables that change the wire’s amp rating. However, that doesn’t mean you should litter your house with copper. The popularity of aluminum continues to persist because copper is too expensive.
Most homeowners can afford to deploy copper for small projects. But the material is not a viable option for large undertakings that use miles of cabling. Aluminum is the perfect alternative.
Yes, it carries fewer amps, but you can remedy this issue by increasing the wire size. Additionally, aluminum is lighter. Aluminum cables are much easier to install.
This matters because 1/0AWG is extremely thick, and thick wires are challenging to install because they don’t have the flexibility you see in lower gauges. 1/0AWG is particularly tricky for consumers that require conduits. Therefore, if you can simplify installation by using a lighter material, you should do so.
1/0 Gauge Watt Rating
1/0AWG has an amp rating of 125A. You get the wattage when you multiply the voltage by the amps. Therefore, 1/0AWG has a watt rating of 1500W at 12V, 15000W at 120V, 30000W at 240V & 60000W at 480V.
| Amp | Voltage | Watt |
| 125A | 12V | 1500W |
| 125A | 120V | 15000W |
| 125A | 240V | 30000W |
| 125A | 480V | 60000W |
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