# Calculating the Current Carrying Capacity of Copper Cables

When it comes to electrical wiring and circuits, the current carrying capacity of copper cables is an important factor to consider. That’s because copper cables have a limited capacity for the amount of electric current they can safely carry before getting overloaded. Knowing how to calculate this value is essential for anyone involved in electrical engineering or who works with electrical systems. Let’s take a closer look at current carrying capacity of cable, cable size and current rating formula.

## The Current Carrying Capacity Formula

The formula for how to calculate current carrying capacity of copper cable is as follows:

I = KA/L.

Here, I stands for the maximum current load in amperes (amps),

K is a constant that depends on the type of material used in the cable,

A stands for the cross-sectional area of the cable in square millimeters (mm2), and L stands for length in meters (m).

For example, if you’re using standard annealed copper wire with a cross-sectional area of 1 mm2 and a length of 10 m, K would equal 0.0175 ohms per meter (Ω/m).

Therefore, your equation would become I = 0.0175 * 1 / 10 = 0.00175 amps or 1.75mA.

This means that your maximum current load would be 1.75 milliamps (mA).

## Formula to Calculate Cable Current Rating

The current rating of a copper cable depends on various factors such as the cross-sectional area of the cable, the type of insulation used, and the installation conditions. A commonly used formula on how to calculate cable current rating is as:

Current Rating = (K * √(Cable Cross-Sectional Area)) / Cable Resistance

Where:

• K is a constant that depends on the installation conditions and other factors. It can be obtained from relevant standards or engineering references.
• Cable Cross-Sectional Area is the area of the copper conductor in square millimeters (mm²).
• Cable Resistance is the resistance of the copper cable per unit length, which can be determined using the resistivity of copper and the length of the cable.

It’s important to note that this formula provides an estimate, and actual current ratings may vary based on specific installation conditions, temperature rise limits, and other factors. It is always recommended to consult with relevant standards, engineering guidelines, or a qualified electrical engineer for accurate current rating calculations for a specific application.

## How to calculate Cable Size

To calculate the power cable size for a given load, there are various methods and formulas that can be used. Here’s an overview of one common approach how to calculate cable size in sq mm:

Calculate the total load or power consumption in kilowatts (kW) or kilovolt-amps (kVA) for the electrical circuit.

### Apply Demand Factor:

Multiply the consumed load by a demand factor to account for diversity and expected usage patterns. The demand factor depends on the specific application and can be obtained from relevant standards or engineering guidelines.

### Calculate Voltage Drop:

Determine the allowable voltage drop based on the specific installation requirements and constraints.

Use the formula: (Actual length of circuit x Volt drop per unit length) / 100 to find the voltage drop for a 100-foot length.

The volt drop per unit length can be obtained from tables or engineering references.

### Select Cable Size:

Once the voltage drop is calculated, select a cable size that can handle the calculated voltage drop while considering factors such as the type of insulation, installation conditions, and current-carrying capacity.

It’s important to note that this is a simplified overview, and actual cable sizing calculations can be more complex, considering factors like ambient temperature, cable derating, short-circuit withstand, and other considerations. It’s recommended to consult relevant standards, engineering guidelines, or a qualified electrical engineer for accurate cable sizing calculations for a specific application.

## Current Calculation Formula

The formula for calculating current in an electrical circuit is:

Current (I) = Voltage (V) / Resistance (R)

This formula is known as Ohm’s Law, which states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance.

Where:

Current (I) is measured in Amperes (A).

Voltage (V) is measured in Volts (V).

Resistance (R) is measured in Ohms (Ω).

## Other Factors To Consider

In addition to using this formula, there are also other factors to consider when calculating current carrying capacity of copper cable, such as voltage drop and temperature rise due to heat dissipation from higher currents flowing through your cable. Therefore, it’s best to consult with an experienced professional before making any assumptions about what kind of loads your cable can handle safely and reliably over time.

## Conclusion:

Calculating the current carrying capacity of copper cables is essential if you want to know how much power they can safely handle without getting overloaded or damaged over time. The power cable size calculation formula and copper cable current carrying capacity formula is fairly straightforward and easy to use, but there are other factors, such as voltage drop and temperature rise, that should be taken into consideration as well before making any assumptions about what kind of loads your cable can handle safely and reliably over time. If you’re still unsure about how much power your copper cables can handle, it’s best to consult with an experienced professional who specializes in electrical engineering so they can help you find out exactly what kind of load they can safely carry without causing any damage or disruption over time.