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Wire size calculator / 2/0 AWG ampacity

How many amps can 2/0 gauge wire carry?

NEC Table 310.16 listings for 2/0 AWG, the selected small-conductor note when this tool has one, and a Chapter 9 Table 8 voltage-drop example. Not a breaker schedule.

Two-aught sits between one-aught and three-aught. The name adds a zero, which looks like a larger jump than the table sometimes is. The only honest comparison is the neighbor cells for ampacity and the neighbor stranded resistances, linked below. Do not scale from the count of zeros.

Resistance at this size is low enough that a short 240 V run can look effortless, which is when people stop checking drop. A detached building or a long feeder can still make drop the governing limit. This page gives you the 2/0 cells and a drop at one stated current. It does not design the feeder.

The example current of 150 A does not equal any copper temperature cell for 2/0 AWG. It is above the 60°C copper cell of 145 A, so a 60°C terminal cap does not cover this current before any other correction. The prefilled calculator uses 240 V, 150 ft one way, 75°C insulation, and 75°C terminals. Those are inputs, not a required circuit.

The selected NEC 240.4(D) column in this tool has no special ceiling for 2/0 AWG. A blank is not permission to omit overcurrent protection. Table ampacity, the terminal cap, and voltage drop still apply.

Aluminum 2/0 AWG is listed at 115 A (60°C), 135 A (75°C), and 150 A (90°C), against copper 145 A, 175 A, and 195 A. Stranded resistance at 75°C is 0.159 Ω/kft aluminum and 0.0967 Ω/kft copper. The same label is not the same conductor. Some equipment permits copper only.

This chart’s Table 8 row for 2/0 AWG publishes stranded resistance only (0.0967 Ω/kft copper, 0.159 Ω/kft aluminum). The calculator uses that stranded value.

Table 8 lists 19 strands and 133100 circular mils for 2/0 AWG. The rounded nominal area is 67.43 mm². Bare stranded diameter is 0.418 in, which excludes insulation and is not conduit fill.

2/0 AWG from NEC Table 310.16 (30°C ambient, not more than three current-carrying conductors) and Chapter 9 Table 8 at 75°C. A dash means no listing. Bare diameter excludes insulation.
ListingCopperAluminum
60°C ampacity (A)145115
75°C ampacity (A)175135
90°C ampacity (A)195150
Stranded Ω/kft0.09670.159
Solid Ω/kft——
Selected 240.4(D) ceiling (A)——
Circular mils133100
Rounded mm²67.43
Strands19
Bare diameter (in)0.418

For 2/0 AWG itself, not for whatever size the calculator recommends, Table 8 stranded copper resistance of 0.0967 Ω/kft at 75°C gives 4.35 V (1.81% of 240 V) using 2 × I × R × L / 1,000. Reactance is omitted. Displayed volts are rounded to two decimals. The same inputs with stranded aluminum resistance 0.159 Ω/kft give 7.16 V (2.98%). If that percentage is outside the prefilled drop limit, the calculator will name a different size. That is the voltage-drop check, not a second ampacity table.

From 1/0 AWG to 2/0 AWG, the 75°C copper listing goes from 150 A to 175 A. Stranded copper resistance at 75°C goes from 0.122 Ω/kft to 0.0967 Ω/kft.

From 2/0 AWG to 3/0 AWG, the 75°C copper listing goes from 175 A to 200 A. Stranded copper resistance at 75°C goes from 0.0967 Ω/kft to 0.0766 Ω/kft.

Planning estimate only. Consult local code and a qualified electrician before buying wire or energizing a circuit. Presets are hypothetical loads; this tool does not design motor, PV, battery, appliance, or EV installations.

Sources for these cells: existing Table 310.16 numerical cells in NFPA’s public development record, pp. 142–143 (proposed changes are not treated as adopted code) and NFPA 70 (2017), Chapter 9 Table 8, printed p. 689, in a third-party-hosted copy. The same publication supplies 110.14 (terminals and aluminum), 210.19/215.2 (continuous loads), 240.4(D) (small conductors), 250.24/250.32 (grounding), and 625.41/625.42 (EV loads). Schneider Electric’s voltage-drop formulas support the arithmetic; Table 8 AC results here omit reactance and assume unity power factor. Resistance and geometry are construction- and temperature-specific. Adopted editions and local amendments can differ.

Related guides

Open the wire size calculator · Ampacity chart · Voltage drop calculator · Printable chart

Check an example against 2/0 AWG

The form starts from this page’s example. The address stays on this guide until you edit a field. After an edit, a shared link includes those settings in the URL, and opening that link sends the URL to the host.

Circuit

Headline metal

Both metals are compared. Verify equipment compatibility; some equipment permits copper only.

System

General NEC notes suggest 3% on a branch or feeder and 5% combined. Special equipment and local codes may require other limits; upstream drop is not included.

Estimated size

Enter the load current and the one-way distance. The size appears here, with the limit that set it.

Temperature and bundling

These conditions affect the table ampacity used for the comparison.

Conductor insulation

Use the rating marked for wet or dry conditions. THHN is 90°C dry; XHHW is 90°C dry or 75°C wet. For NM-B use 90°C insulation and a 60°C cap below.

Terminal / cable ampacity cap

Use the lowest applicable rating at either end, including cable limits. The general unmarked default is 60°C for equipment rated ≤100 A or marked for 14–1 AWG. Confirm equipment markings before selecting 75°C; NM-B remains capped at 60°C.

Equipment grounding conductors are excluded. Verify neutrals, harmonic loads, and all other current-carrying conductors in the raceway or cable; the automatic count does not check these.

AC impedance (Chapter 9 Table 9)

At power factor 1, the reactance term is zero, but Table 9 AC resistance still applies. Unlisted sizes have no Table 9 result.

Planning estimate only. Consult local code and a qualified electrician before buying wire or energizing a circuit. Presets are hypothetical loads; this tool does not design motor, PV, battery, appliance, or EV installations.

Questions

How many amps can 2/0 gauge wire carry?

2/0 AWG copper in NEC Table 310.16 is listed at 145 A at 60°C, 175 A at 75°C, and 195 A at 90°C. Aluminum 2/0 AWG is listed at 115 A (60°C), 135 A (75°C), and 150 A (90°C), against copper 145 A, 175 A, and 195 A. Stranded resistance at 75°C is 0.159 Ω/kft aluminum and 0.0967 Ω/kft copper. The same label is not the same conductor. Some equipment permits copper only. Those cells assume not more than three current-carrying conductors and 30°C ambient. They are not a breaker size by themselves. The selected NEC 240.4(D) column in this tool has no special ceiling for 2/0 AWG. A blank is not permission to omit overcurrent protection. Table ampacity, the terminal cap, and voltage drop still apply. Planning estimate only. Consult local code and a qualified electrician.

Does a hotter temperature column raise the breaker for 2/0 AWG?

This tool’s selected NEC 240.4(D) column has no special ceiling for 2/0 AWG. The blank is not permission to omit overcurrent protection, and it does not turn the 90°C cell into a breaker rating. Terminal and cable limits still cap the usable ampacity. Exceptions in the code are not checked. Planning estimate only. Consult local code and a qualified electrician.

What voltage drop does 2/0 AWG have on the example?

For 2/0 AWG itself, not for whatever size the calculator recommends, Table 8 stranded copper resistance of 0.0967 Ω/kft at 75°C gives 4.35 V (1.81% of 240 V) using 2 × I × R × L / 1,000. Reactance is omitted. Displayed volts are rounded to two decimals. The same inputs with stranded aluminum resistance 0.159 Ω/kft give 7.16 V (2.98%). If that percentage is outside the prefilled drop limit, the calculator will name a different size. That is the voltage-drop check, not a second ampacity table.

Is 2/0 twice 1/0?

No. The names are ordered sizes, not a multiplier. Compare the Table 310.16 cells and the Table 8 stranded resistances of 1/0, 2/0, and 3/0. The steps are whatever those rows print.