The gauge and ampacity of a wire go hand in hand. You have to identify a wire’s gauge to determine the amount of current it will carry. Once you know the gauge, you can find the ampacity. Though, the reverse is also possible. Knowing the gauge and ampacity enables you to pair the correct wire with the proper application.
How Many Amps Can 18AWG Handle?
According to NEC, 18AWG Copper wire can carry 14 amps at 90 degrees. It has a diameter of 1.024mm and a cross-section of 0.823mm2
| 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 | 75˚C THW, THWN, SE, USE, XHHW | 90˚C XHHW-2, THHN, THWN-2 |
| 18AWG | – | – | 14 | – | – |
The ampacity rating depends on various factors, including the voltage rating, non-reactivity, density, flexibility, and flammability, to mention but a few.
Of all these factors, the temperature is one of the most important.
Higher temperatures tend to attract greater ampacity ratings than lower temperatures.
This is why many professionals specify the ambient temperature whenever they consider wire gauges and ampacity ratings. They also consider the duty cycle because some loads, such as electrical motors, use more current during startup.
The wire’s gauge and ampacity must accommodate that brief spike in current. Otherwise, you may start a fire.
How many Amps Can 18 Gauge Wire Handle At 12 Volts?
18AWG can handle .25A to 10A, depending on the distance.
| 18AWG 12 Volt | Distance |
| .25A | 376 |
| .33A | 285 |
| .42A | 224 |
| .83A | 113 |
| 1.67 | 56 |
| 2.50A | 38 |
| 3.33A | 28 |
| 4.17A | 23 |
| 5A | 19 |
| 5.83A | 16 |
| 6.67A | 14 |
| 7.50A | 13 |
| 8.33A | 11 |
| 9.17A | 10 |
| 10A | N/A |
How many Amps Can 18-Gauge Wire Handle At 24 Volts?
18AWG wire can carry between 10 and 50 VA depending on the distance.
| 18AWG 24 Volt | Distance |
| 10VA | 451ft |
| 20VA | 225 ft |
| 30VA | 150 ft |
| 40VA | 112 ft |
| 50VA | 90 ft |
How many Amps Can 18-Gauge Wire Handle At 120 Volts?
18-gauge wire can handle 14 amps (1680 watts)
How many Amps Can 18-Gauge Wire Handle At 220 Volts?
18-gauge wire can handle 14 amps (3080 watts)
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Uses of 18-Gauge Wire
- 18AWG wire is not particularly thick. People use it for low-voltage lighting.
- With extension cords, it is somewhat different. 18-gauge extension cords can handle power tools like sanders, drills, and any other device with a rating as high as 600 watts.
What is 18-Gauge Wire Rated For?
18AWG wire is rated for low-voltage lighting
Does Material (Aluminum/Copper) Change Its Amps?
The material affects the amperage. Copper and aluminum are the most common materials:
1). Copper
Between the two, copper is more popular. Contractors prefer to use the material for building wire. You will also find it in most electronics and power distribution equipment. It is popular due to its conductivity. The material is the most conductive metal in the field, so local and international contractors use it in electrical projects.
It has a lower coefficient of thermal expansion, which means that it is less likely to change in volume (as a function of temperature). Copper may gain a green patina after prolonged exposure to the atmosphere, but the material resists corrosion.
The patina won’t affect the copper wire’s performance. Therefore, you can use the cables in salty environments without deploying additional protective mechanisms to defend against oxidation.
2). Aluminum
This material is 61 percent less conductive than copper. However, it is also 30 percent the weight of copper. On the one hand, this is a good thing because aluminum wires are easier to handle.
On the other hand, the weight of copper makes wires more stable where the installation of submarine cables is concerned. Even though it is cheaper, aluminum continues to lose points because it reacts to water, producing hydrogen gas which can damage the wires.
Copper doesn’t react to water, making the material appealing to people who have to ship and handle it.
Many people use aluminum despite its weaknesses because of the high cost of copper. And to be fair, you can use aluminum in place of copper. But you must adjust the size and ampacity.
According to Leonardo Energy,
Aluminum cables that have to replace copper wires require a cross-sectional area that is 56 percent larger than the cross-sectional area of the copper wire.
Simply put, you need thicker aluminum conductors to perform the same task as thinner copper wires. For instance, to replace 8-gauge copper wires, you should install 6-gauge aluminum wires. This applies to 60A at 75 degrees C.
Because you need thinner copper conductors to carry the same volume of electricity as a thicker aluminum conductor, copper wires are technically easier to install than their aluminum counterparts, even though aluminum cables are lighter.
If that hasn’t convinced you to prioritize copper, the material is not as brittle as aluminum.
Advantage of Knowing Amps for 18 Gauge Wire
Knowing the appropriate amps for 18-gauge wire allows you to pair 18-gauge wire with suitable applications.
The thickness of a wire determines the amount of current it can safely transmit. Thinner wires can transmit less current than thicker wires.
The cables will overheat if you use thin conductors to operate a heavy-duty appliance. This is because every wire has a certain amount of resistance. That resistance generates heat whenever a current passes through the wire.
If the wire transmits more electricity than it can handle, it will produce dangerous amounts of heat, the kind that melts the insulation and starts fires. You can avoid this outcome by making sure that the cable is thick enough to withstand the demands of the application in question.
If you know that 18AWG wire can safely handle 14 amps, you can ensure that your contractor never uses 18AWG conductors in situations that exceed 14 amps. It is a question of safety.
You have to keep the applications you pair with 18-gauge wire within the limits the conductors can handle. Even if the insulation is strong enough to withstand the heat, you may shorten the appliance’s lifespan because of the voltage drop.
Does Distance Affect its Amp?
The distance does not directly affect the amperage. Instead, the distance impacts the gauge.
As was noted earlier, wires have resistance. When the current in the wire encounters resistance, heat is generated. If you increase the length of the wire, the resistance will increase.
This elevates the heat and voltage drop. Some appliances won’t perform as effectively as you expect because the voltage drop has prevented them from accessing the electricity they need to operate optimally.
Others will work as expected, but only because they are drawing more current than usual to compensate for the voltage drop. This is a bad thing because an increase in the current will inevitably result in overheating.
You solve this problem by increasing the gauge. If you want the wire to cover a long distance, a thicker gauge can transmit the current over that distance without increasing the resistance, voltage drop, and heat generated.
If the gauge increases, the wire’s ampacity will increase as well. If you don’t want to change the gauge, you have to reduce the current the conductor will carry. IN other words, a long 18AWG wire has a lower ampacity rating than a short one.
Maximum Current For 18AWG Wire
The current is measured in amps. An 18-gauge wire can handle 16 amps.
How Many Amps Can 18 Gauge Stranded Wire Handle?
The average amp rating of an 18-gauge wire is 14A. Though, solid cables have a higher current carrying capacity than stranded wires. Don’t be surprised if your contractor pushes you to limit your 18AWG stranded wire to 7-amp applications.
How Many Amps Can 18 Gauge Automotive Wire Handle?
18-gauge automotive wire can handle anywhere between 3 and 15 amps, depending on the distance (12.2 ft to 2.4 ft). The shorter the wire, the more current it can handle.