AWG cables: How they work, conversion & selection guide

According to the AWG system, wire size is represented by a number corresponding to the conductor diameter. A distinctive feature is that the smaller the AWG number, the larger the wire diameter, and vice versa. For example, AWG 16 wire has a larger diameter than AWG 20 wire. At the same time, sizes are determined according to a fixed geometric progression. Specifically, every decrease of 3 AWG sizes doubles the conductor's cross-sectional area, while every decrease of 6 AWG sizes doubles its diameter.

The conductor diameter determines its cross-sectional area, which directly affects electrical resistance. For the same material and length, a wire with a larger AWG number has lower resistance, whereas a wire with a smaller AWG number has higher resistance. This also means that wires with smaller AWG numbers generally help reduce voltage drop and power loss during current transmission, provided all other conditions remain unchanged.

💡Useful information: Why the same 2.5 mm² cable heat differently: Beyond the label?

When is it necessary to convert AWG to the meter system? Converting AWG to mm² is often necessary when importing equipment from the United States, Japan, or Taiwan, reading electrical circuit diagrams based on American standards, or selecting replacement cables compatible with the metric system. Similarly, when selecting cable lugs, connectors, or cable glands, comparing the two sizing systems helps identify suitable specifications and minimize discrepancies during installation.

To convert conductor sizes of AWG cables to the meter system, you can use formulas to calculate the conductor diameter and cross-sectional area. When determining the AWG size from a known diameter or cross-sectional area, the result is rounded to the nearest corresponding AWG size.

3.1. Formula for calculating conductor diameter (mm)

The diameter of an AWG cable with size n, denoted by dₙ, is calculated using the following formula:

Where:

• dₙ: conductor diameter, in mm
• n: AWG size to be converted
• 0.127 mm: nominal diameter of AWG 36 wire

3.2. Formula for calculating conductor cross-sectional area (mm²)

After determining the diameter, you can calculate the conductor's cross-sectional area using the following formula:

Alternatively, calculate it directly from the AWG number:

Where:

• Aₙ: conductor cross-sectional area, in mm²
• dₙ: conductor diameter, in mm
• π: the mathematical constant Pi, approximately 3.14159
• n: AWG size to be converted

For convenient reference and wire selection, the following table summarizes common AWG sizes, their corresponding diameters (mm, inches), and cross-sectional areas (mm²), helping you easily compare specifications between the two sizing systems.

To select conductors according to the AWG standard, you need to consider the following important factors:

5.1. Conductor material

The conductive material directly affects the wire's resistance and current-carrying capacity.

• Copper: Has high electrical conductivity and generally allows a smaller cross-sectional area than aluminum under equivalent load conditions.
• Aluminum: Is lighter and can reduce material costs, but generally requires a larger cross-sectional area to achieve conductivity equivalent to copper.

5.2. Conductor construction

Conductor construction is also a factor to consider:

• Solid wire: Has a rigid structure and is suitable for certain fixed installations, such as wiring inside walls or electrical cabinets.
• Stranded wire: Consists of multiple small conductive strands and offers greater flexibility, making it suitable for moving machinery, areas subject to vibration, or locations requiring frequent bending.

5.3. Current-carrying capacity

Conductors must accommodate the circuit's maximum current to prevent overheating during operation. Depending on the application, the following AWG ranges can be used as a reference:

• Low current loads: AWG 14–18, commonly referenced for lighting systems or low-power electrical equipment.
• Medium current loads: AWG 10–12, which may be used in certain applications such as HVAC systems and high-power electrical equipment.
• High current loads: AWG 6–8 or wires with larger cross-sectional areas, depending on the requirements of applications such as EV chargers and high-power motors.

Please note that the ranges above are for reference only and are not current ratings applicable to every situation. You need to check current electrical standards and the wire's technical specifications to determine the appropriate size.

5.4. Voltage drop along the wire

When electric current flows through a conductor, resistance causes voltage drop. The longer the wire, the greater the voltage drop generally becomes, provided all other conditions remain unchanged.

Voltage drop can be calculated using the following formula: Voltage drop (V) = Current (A) × Resistance (Ω)

For example, for an AWG 16 cable with a total circuit length of 20m for the outgoing and return conductors, carrying a current of 10A and having a resistance of approximately 0.263Ω, the voltage drop will be 2.63V. With a 12V power supply, this voltage drop accounts for approximately 21.9%, which is relatively high. In this case, you may consider using a wire with a larger cross-sectional area, such as AWG 14 or AWG 12, to reduce the voltage drop.

5.5. Installation environmental conditions

Temperature, humidity, UV radiation, and chemicals can affect the durability of the insulation as well as the conductor's operating performance.

• High-temperature environments: Select wires with insulation materials and temperature ratings suitable for the conditions. Current-carrying capacity may need to be derated according to actual operating conditions.
• Outdoor installations: Use wires with insulation or protective sheathing suitable for UV exposure and weather conditions.
• Areas with chemicals or high humidity: Consider chemical resistance, moisture resistance, and the system's protection requirements.

For reference when selecting AWG cables, please check the following table:

For wire runs longer than 50 ft (15.24 m), you should consider using a wire with a larger cross-sectional area (corresponding to a smaller AWG number) to limit voltage drop. In addition, when selecting AWG cables for outdoor systems or machinery that moves frequently, remember to consider the current load, installation conditions, and requirements for insulation and conductor flexibility to ensure suitability for the operating environment.

We HELU Vietnam offer a range of AWG 18 and AWG 16 cables designed to meet various industrial applications and installation requirements. Refer to the table below to explore the key features of each cable series and identify the right product for your needs.

7.1. 18 AWG cables from HELU

7.2. 16 AWG cables from HELU