2/0 AWG Copper Wire Ampacity: NEC Ratings, Derating and Sizing Guide

How many amps can a 2/0 AWG copper wire carry?

Under the base conditions of NEC Table 310.16, a 2/0 AWG copper conductor has an ampacity of 145 A at 60°C, 175 A at 75°C, or 195 A at 90°C.

However, these values are not universal current limits. The usable ampacity depends on conductor insulation, equipment termination ratings, ambient temperature, conductor grouping and load characteristics.

This guide explains the key factors engineers and buyers should consider when selecting 2/0 AWG copper conductors for power distribution projects.

1. 2/0 AWG Copper Wire Ampacity Chart

A 2/0 AWG copper conductor, also designated 00 AWG, has a nominal metallic cross-sectional area of approximately 67.4 mm².

The following values apply under the base conditions of NEC Table 310.16: 30°C (86°F) ambient temperature, not more than three current-carrying conductors, and an installation within the table's scope.

Reference: NEC Table 310.16.

The applicable column depends on the conductor insulation and equipment temperature limitations.

For example, a 90°C-rated conductor does not automatically have a usable circuit ampacity of 195 A.

2. Why 90°C Insulation Does Not Always Mean 195 A

Under NEC 110.14(C), conductor selection must account for the temperature ratings of connected equipment terminations.

Consider an installation with:

• 2/0 AWG copper conductors.

• 90°C-rated insulation.

• 75°C-rated equipment terminations.

• 30°C ambient temperature.

• Three current-carrying conductors.

Although the conductor has a 90°C base ampacity of 195 A, the applicable 75°C termination limitation restricts its usable ampacity to 175 A under these conditions.

The 90°C ampacity may still be used as the starting point for permitted ambient-temperature correction and conductor-count adjustment calculations. The resulting value must then be checked against the applicable termination limitation.

Key point: Always verify the insulation rating and equipment termination rating before selecting a conductor.

3. Continuous Load Sizing

The NEC defines a continuous load as one for which the maximum current is expected to continue for three hours or more.

For many conventional feeder and branch-circuit applications, conductor sizing must account for 125% of the continuous load plus 100% of the noncontinuous load, subject to applicable exceptions.

Example: 175 A Continuous Load

Assume:

• Continuous load: 175 A.

• Copper conductors.

• 75°C terminations.

• 30°C ambient temperature.

• No additional correction or adjustment factors.

Required conductor ampacity:

175 A × 1.25 = 218.75 A

Under these assumptions, 2/0 AWG and 3/0 AWG copper do not meet the calculated 218.75 A requirement.

A 4/0 AWG copper conductor meets this illustrative ampacity requirement before any additional correction or adjustment factors.

The final conductor and overcurrent protection selection must comply with the applicable NEC provisions and equipment requirements.

4. Ambient Temperature and Conductor Derating

NEC Table 310.16 base ampacities assume an ambient temperature of 30°C.

Higher ambient temperatures and installations with more than three current-carrying conductors may require ampacity correction or adjustment.

Example: 50°C Ambient Temperature

For 2/0 AWG copper at 50°C ambient:

The correction factors are taken from NEC Table 310.15(B)(1).

If the 90°C-rated conductor is connected to 75°C-rated terminations, the corrected value of 159.9 A is below the 175 A termination limitation.

Under these stated conditions, its usable ampacity is therefore 159.9 A, before any additional adjustment factors.

More Than Three Current-Carrying Conductors

Where NEC 310.15(C)(1) applies, conductor-count adjustment factors may further reduce ampacity.

For example, five current-carrying conductors generally require an 80% adjustment factor under the applicable table conditions.

For 2/0 AWG copper with 90°C insulation:

195 A × 0.80 = 156 A

The final usable ampacity must also satisfy the applicable termination limitation and any other required corrections.

5. Common Questions About 2/0 AWG Copper

Is 2/0 AWG Copper Rated for 175 Amps?

Yes. Under the base conditions of NEC Table 310.16, 2/0 AWG copper has an ampacity of 175 A in the 75°C column.

The actual usable ampacity may be lower depending on installation conditions.

Can 2/0 AWG Copper Be Used for a 200 A Feeder?

Not automatically.

The conductor must satisfy the applicable load calculation, temperature limitations, correction factors and overcurrent protection requirements.

A 2/0 AWG copper conductor should not be specified for a 200 A feeder solely because its 90°C base ampacity is 195 A.

Is 2/0 AWG the Same as 70 mm²?

No.

The nominal metallic area of 2/0 AWG is approximately 67.4 mm². A 70 mm² conductor is a different nominal size commonly used in IEC-based specifications.

The two should not be treated as interchangeable without verifying the applicable conductor and project requirements.

6. Request a Quote from Xinyu Cable

Xinyu Cable manufactures low- and medium-voltage power cables for utility distribution, industrial facilities, infrastructure and renewable energy projects.

For international enquiries involving AWG conductor sizes, please provide:

• Required conductor size and material.

• Insulation type and voltage rating.

• Number of conductors and cable construction.

• Applicable product standard.

• Required cable length or bill of quantities (BOQ).

Contact Xinyu Cable for technical review and quotation.