0 Gauge Wire: 1/0 Aluminum & 1/0 Copper Wire

0 gauge wire is a relatively thick wire that can carry a lot of Amps, regardless if it is made out of aluminum or copper.

0 gauge wire is often written as 1/0 gauge wire and should not be confused with 1 gauge wire.

0 gauge wire is rarely used by homeowners since it is not used for typical applications one finds in residential buildings. But it is a good thing to know a thing or two about this wire size...

Published: October 31, 2022.

0 Gauge Wire Physical Dimensions

0 gauge wire consists of solid or stranded wires made of pure copper, aluminum, Copper Clad Aluminum (CCA), OFC (Oxygen Free Copper) copper, etc.

The physical dimensions of the solid copper 0 gauge wire are:

• Diameter: 8.2515 mm, 0.3249 inches,
• Cross Section: 53.4751 mm², 0.0829 inches².

Since stranded wires feature air gaps between the individual strands (~20-25% of the stranded wire cross section is actually - air), the diameter of the stranded wires with the same Ampacity (wire current carrying ability) is ~12-14% larger than the diameter of the solid wire (~9.3 mm on average).

However, solid ~8 mm copper wire is not easy to work with, to say the least, making this 12-14% diameter difference mostly negligible for typical applications of the 0 gauge wire (welding wire, high-power audio wire, etc.).

Note: some stranded wires can have larger diameters, depending on their construction, used materials, and similar.

0 Gauge Wire vs. 1/0 Gauge Wire vs. 1 0 Wire Gauge vs. 1 Gauge Wire

Before diving deeper into the features and use of 0 gauge wire, let's discuss a little bit about:

• 0 Gauge Wire,
• 1/0 Gauge Wire,
• 1 0 Wire Gauge,
• 1 Gauge Wire.

0 gauge wire, 1/0 gauge wire, and 1 0 wire gauge represent the same wire thickness - it's just written differently.

However, "1/0" or "1 0" gauge wire should not be confused with "1" gauge wire, which is one step thinner wire than the 0 (or "1/0" or "1 0") gauge wire.

0 Gauge Wire Ampacity: Aluminum vs. Copper Wire

0 gauge wire is commonly made using copper, which is for the same wire thickness better conductor than aluminum, which is for the same weight better conductor than copper. Simple as that.

The Ampacity of the solid 0 gauge wire depends on the material, and the maximum allowed wire temperature:

0 Copper Wire:

• @60°C/140°F: 125 Amps
• @75°C/167°F: 150 Amps
• @90°C/194°F: 170 Amps

0 Aluminum Wire:

• @60°C/140°F: 100 Amps
• @75°C/167°F: 120 Amps
• @90°C/194°F: 135 Amps

For comparison purposes, 1 gauge solid copper wire Ampacity is:

• @60°C/140°F: 110 Amps
• @75°C/167°F: 130 Amps
• @90°C/194°F: 145 Amps

Again, if You are looking for a "1/0" or "1 0" gauge wire, You need a 0 gauge wire, NOT a 1 gauge wire.

The default Ampacity values for both copper and aluminum wires don't feature any safety margin, hence the 80% Rule.

80% Rule

The 80% Rule states that the actual wire Ampacities should be 80% of the default values.

Thus, we can write:

Since @60°C/140°F is the maximum allowed surface temperature for many applications, we can say that 0 AWG copper wire can safely handle 100 Amps, while 0 AWG aluminum wire can safely handle 80 Amps.

Wire Length

The longer the wire, the bigger the energy losses since copper and aluminum are not ideal conductors.

A general rule of thumb is to decrease Ampacity by 10% for every 50 feet (~15 m) of wire.

For example, to keep energy losses to an acceptable level, a maximum Ampacity of 100 feet 0 copper wire is:

Ampacity = 125 A * 0.8 / 1.2 = 83.3 Amps

The following chart lists the Ampacity (given in Amps) of 0 gauge copper wire at default temperatures for the wires of 50, 100, 150, and 200 feet long.

Note: a similar calculation can be done easily for the 0 gauge aluminum wire.

0 Gauge Wire Frequently Asked Questions (FAQ)

Here are some of the most common Frequently Asked Questions (FAQ) about 0 gauge wires and wires in general:

What is a 1/0 gauge wire? How thick is 0 gauge wire? What size wire is 0 gauge?

1/0 gauge wire, also written as 1 0 gauge wire or simply 0 gauge wire, is a solid wire featuring dimensions of:

• Diameter: 8.2515 mm, 0.3249 inches,
• Cross Section: 53.4751 mm², 0.0829 inches².

How many Amps can 0 gauge wire handle? How many Amps can 1/0 aluminum wire carry?

The actual Ampacity of 0 gauge wire depends on the wire material, maximum allowed surface temperature (if unsure, always go for 60°C/140°F), and wire length.

Generally, short 0 gauge copper wire can safely handle 100 Amps, and 0 gauge aluminum wire can safely handle 80 Amps.

When should you use 0 gauge wire?

0 gauge wire is commonly used in welding applications, as an audio wire, as a battery wire, and similar.

How hot can OFC (Oxygen Free Copper) 0 gauge wire get?

For safety reasons, OFC 0 gauge wire should not be subjected to surface temperatures higher than recommended by their manufacturer.

In most applications, this means 60°C/140°F - a wire with a surface temperature of 60°C/140°F can be held for 4-6 seconds with bare hand by most adults.

Personally, if your 0 gauge wire is overheating that You can't hold it comfortably, that wire is under really high load - turn your gear off and check if something is wrong.

Note: it is much safer to measure the cable/wire surface temperature using digital contactless thermometers...

How to tell the difference between 0 gauge OFC (Oxygen Free Copper) and CCA (Copper Clad Aluminum) wire?

The easiest method and highly recommended - read the labels.

If labels are unavailable, check the cross-section of the wires - CCA wires feature a thin layer of copper on an aluminum core, while OFC wires are copper-only wires.

Long Story Short: 0 gauge aluminum and copper wires are rarely used at homes, but they have other purposes, as previously mentioned.

Solid wires are thinner, but solid 0 gauge copper wires are really hard to work with - imagine rewiring the car's high-end audio system with a solid 0 gauge wire...

If You are adapting your home electric installation, car's or RV's electric system, or something similar and You are unsure about wire thicknesses, materials, crimping, and similar, it is highly recommended to find a local certified electrician (or company) for consultations and for finishing the task ...

It is the safest and cheapest option in the long run!