6 Gauge Wire Amps: 6/2 Wire vs. 6/3 Wire vs. 6/4 Wire

6 gauge wires are often used in marine, residential, and even industrial applications where a medium-sized wire is required to transfer plenty of energy without significant energy losses.

Since the requirements of such applications differ, so do the 6 gauge wires differ in the wire and insulation material, wire construction, and similar.

Updated: May 3, 2023.

6 Gauge/6 AWG Wire Features and Specifications

The physical dimensions of the solid copper 6 gauge wire, also often written as 6 AWG wire, are:

• Diameter: 4.1154 mm, 0.1620 inches,
• Cross Section: 13.3018 mm², 0.0206 inches².

However, wires can be made using other materials as well, not just "solid copper", and each such material can lead to 6 gauge wires of slightly different diameters.

6 gauge wires can also be made using:

• Aluminum: aluminum is lighter than copper, but it also features higher electrical resistance. Thus, aluminum wires of the same Ampacity (current carrying ability) are thicker but lighter.
• Copper Clad Aluminum (CCA): CCA wires feature an aluminum core and outer copper cladding, leading to wires that are lighter than copper wires but also feature better conductivity than aluminum wires.
• Stranded Wires are easier to work with than solid wires since they contain many, often very thin wires. As such, stranded wires have a diameter that is slightly larger than solid copper wires.
• Tinned Stranded Copper Wires feature numerous tinned thin wire strands and are very resistant to corrosion. Such wires are often used in marine and light industrial applications. But, one must be aware that such wires are slightly thicker than solid copper wires - for example, tinned stranded 6 gauge 3200/0.08 copper wire features a diameter of ~5.2 mm, while solid 6 gauge copper wire features a diameter of ~4.1 mm.

6 Gauge/6 AWG Wire Ampacity

If we check the Ampacity of the 6 gauge enclosed solid copper wire, then:

• @60°C/140°F: 55 Amps,
• @75°C/167°F: 65 Amps,
• @90°C/194°F: 75 Amps.

This is the default Ampacity of the solid enclosed 6 gauge copper wire, and these values don't include any safety margin - time for "Rule 80%".

Rule 80%

Rule 80% states that the actual wire ampacity is 80% of its default ampacity. Thus, we can write:

• @60°C/140°F: 55 Amps * 0.8 = 44 Amps,
• @75°C/167°F: 65 Amps * 0.8 = 52 Amps,
• @90°C/194°F: 75 Amps * 0.8 = 60 Amps.

These are actual Amps that 6 gauge wire can transfer to shorter distances and still keep the energy losses low.

Wire Length

When the wire is long, the Ampacity must be decreased by 10% for every 50 feet (~15m) of wire to keep the energy losses at a certain level.

For example, the actual Ampacity for a 100 feet long 6 gauge wire with the maximum allowed surface temperature of 60°C/140°F would be:

Ampacity = 55 * 0.8 / 1.2 = 36.66 Amps

The following chart lists the Ampacity (given in Amps) of 6 gauge wire at default temperatures for the wires of 50, 100, 150, and 200 feet long.

Since the maximum allowed temperature for residential use is 60°C/140°F, the second column shows the actual Ampacity (current carrying ability) of 6 gauge wire depending on its length.

So, if You wonder about the 6 gauge wire, Ampacity (or Amps) for residential use is 44 Amps for shorter wires.

If the wires are longer, then 50 feet long 6 gauge wire can handle ~40 Amps, 100 feet long 6 gauge wire can carry 36.6 Amps, 150 feet long 6 gauge wire can carry 33.8 Amps, and 200 feet long 6 gauge wire can carry 31.4 Amps.

6 Gauge/6 AWG Wires Ampacities In Free Air: 6 Gauge Copper Wire vs. 6 Gauge Aluminum Wire

For the same thickness, aluminum wire is lighter but features higher electrical resistance and, thus, lower Ampacity. But, for the same weight, the aluminum wire has lower electrical resistance and thus higher Ampacity.

The following chart shows theoretical (no 80% Rule, for example) Ampacities of 6 gauge wires in free air, according to their material and maximum allowed surface temperature:

The resistivity of pure copper is 16.78 nΩm @20°C, and the resistivity of pure aluminum is 26.5 nΩm @20°C.

Note: In real-life wires, the actual resistivity of these materials is a little bit higher; for example, actual copper resistance is often very close to ~17.24 nΩm @20°C.

So, if You need lighter wire, it is perhaps better to use somewhat thicker aluminum wire which has the same or higher Ampacity as copper wire but which is still lighter.

6 Gauge Wire Cables: 6/2 Wire, 6/3 Wire, and 6/4 Wire

Wires are rarely used individually - they are most often arranged in cables consisting of several wires.

Hence, cables can be labeled as 6/2 Wire (6 2 Wire), 6/3 Wire (6 3 Wire), and 6/4 Wire (6 4 Wire) - cables with more wires are generally rare and are often custom built.

When the cable is labeled as, for example, "6/3 Wire", that means that it is a cable consisting of three 6 gauge wire conductors and one ground wire. Thus:

• 6/2 Wire, sometimes written as "6 2 Wire", consists of two wire conductors and one ground wire.
• 6/3 Wire, sometimes written as "6 3 Wire", consists of three wire conductors and one ground wire.
• 6/4 Wire, sometimes written as "6 4 Wire", consists of four wire conductors and one ground wire.

And the best of all is that these wires are color coded in order to help the user properly connect them.

Actual color codes depend on the intended wire/cable use, and for residential use (120/208/240V AC), they are Black (phase 1), Red (phase 2), Blue (phase 3), and White (neutral), while the ground wire is usually bare wire, Green wire, or Green wire with Yellow stripes.