# How Many Amps Can a 10 Gauge Wire Handle? (Answered)

Written by Edwin Jones / Fact checked by Andrew Wright

You’re wiring an electric clothes dryer or a 240-volt air conditioner, and the assembly requires you to use a 10-gauge wire. But then you wonder, how many amps can a 10 gauge wire handle?

A 10-gauge wire can handle 30 amps by default. However, this measurement can change depending on certain factors, such as temperature and wire length.

In this article, you will learn everything you need to know about these factors, as well as how to measure the amps of your devices.

## Amp Rating of 10 AWG Wire

According to the National Electrical Code (NEC) 310-16, the 10-gauge wire amp rating at 60 degrees Celsius (140 degrees Fahrenheit) can allow up to 30 amps to go through without overheating, but this reading can vary because of other factors.

## Factors Affecting Wire Amp Handling

### 1. Temperature

One of the factors that affect the current capacity of a 10-gauge wire is the temperature. Note that a rise in temperature generally increases cable ampacity.

For example, a 10-gauge wire’s max amps at 60 degrees Celsius (152 degrees Fahrenheit) is 30 amps. But it increases to 35 amps if the temperature of the compounds in and around the wire is 75 degrees Celsius (167 degrees Fahrenheit).

### 2. Wire Length

Power typically loses potency as the wire’s length increases. The current rating also decreases as the wire lengthens.

For instance:

 Wire Length Wire Gauge Ampacity 50 feet 10-gauge 21.8 amps 150 feet 10-gauge 18.4 amps

### 3. The 80% Amperage Rule

The ampacity adjusts depending on the number of carrying conductors. A good rule of thumb is to reduce the maximum amperage of a copper wire if it has four to six conductors or more.

One way to determine the number of conductors in a cable is to check its label. The following are the typical number of conductors for different 10-gauge wires:

• 10/2 wire: Two conductors and one ground
• 10/3 wire: Three conductors and one ground
• 10/4 wire: four conductors and one ground

### 4. Ampacity Table and Calculations

Finding out the ampacity of a wire is possible with the help of Ohm’s Law. You can calculate it using the following formula:

$\text{Current in Amps} = \frac{\text{Voltage}}{\text{Resistance}}$

For example, a 12v battery connected to a 10-gauge wire with a 6-ohm resistance results in a 2-amp draw.

Also, calculate the voltage drop by multiplying the current in amperes by the 10-gauge wire’s length in feet. Then, divide the result by 100 before multiplying the value indicated in the table below based on the conductor’s material and load power factor:

 Conductor Material Steel Load Power Factor (%) Aluminum or Non-Metallic Load Power Factor (%) 80 90 100 80 90 100 Copper 0.179 0.198 0.215 0.178 0.197 0.215 Aluminum 0.274 0.318 0.336 0.274 0.305 0.336

For instance, a 220V, 100HP motor is drawing 124A at full load. Assuming that it’s running at 80% capacity through a 150-foot wire, the formula to find out the voltage drop is:

\begin{align*} \text{Voltage Drop} &= \frac{124 \, \text{amps} \times 150 \, \text{feet}}{100} \times 0.179 \times \frac{1}{460} \\ &= 0.072\% \end{align*}

Then, use the voltage drop measurement and subtract it from the maximum voltage to determine the current value. In this case, that would be:

$220 \, \text{V} – (220 \, \text{V} \times 0.072\%) = 204.16 \, \text{V}$

Next, assuming that the unit has a 6-ohm resistance, the current would now be:

$\frac{204.16 \, \text{V}}{6 \, \Omega} = 34.027 \, \text{A}$

Alternatively, checking a wire length to amp matrix can also give you a power draw estimate for your 10-gauge wire. The matrix will look something like this:

 Wire Length At 60 Degrees Celsius/140 Degrees Fahrenheit Default 30 50 feet 21.8 100 feet 20 200 feet 17.1

## Conclusion

The short answer to how many amps can a 10 gauge wire handle is, according to the NEC, is 30 amps by default. The long answer is it depends, so you should also pay attention to the different factors affecting the wire’s amp draw.

For instance, a 200-foot 10-gauge wire with a running temperature of 75 degrees Celsius (167 degrees Fahrenheit) may have an ampacity of 20 amps. However, temperature is one of the various elements you should check to determine the wire’s correct ampacity.

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