2 AWG ampacity by temperature column
| Conductor | 60°C | 75°C | 90°C | 240.4(D) |
|---|---|---|---|---|
| Copper | 95 A100 A breaker | 115 A125 A breaker | 130 A150 A breaker | no cap |
| Aluminum | 75 A80 A breaker | 90 A90 A breaker | 100 A100 A breaker | no cap |
Ampacities are NEC Table 310.16 values for a conductor at 30°C ambient in a raceway, cable, or direct burial with three or fewer current-carrying conductors. Ambient correction and conductor adjustment are applied to these numbers before the 240.4(D) cap is checked, never after it.
What size breaker for 2 gauge wire
- 2 AWG copper: 100 A on a 60°C column and 125 A on a 75°C column.
- 2 AWG aluminum: 80 A on a 60°C column and 90 A on a 75°C column.
No small-conductor cap applies at this size, so the device follows the column the equipment is listed for: 100 A on the 60°C column and 125 A on the 75°C column. Where an ampacity falls between standard ratings, 240.4(B) permits the next size up, so 100 A protects the 95 A 60°C ampacity and 125 A protects the 115 A 75°C ampacity. It relaxes the device rather than the conductor: 210.19(A)(1) still requires an ampacity at least equal to the calculated load. The allowance does not reach a multioutlet branch circuit supplying receptacles for cord-and-plug-connected portable loads, and it stops at an 800 A device. Aluminum at this size takes 80 A at 60°C and 90 A at 75°C, since 240.4(B) carries the device to the next standard rating where the ampacity falls between two. 334.80 and 340.80 hold NM-B and UF-B cable to the 60°C column whatever the terminals are marked, so a cable assembly is read from the left-hand column while conductors in raceway are read from the column the equipment is listed for.
What 2 gauge wire is used for
- 100 A to 125 A feeders and panel changes
- Ground rings and grounding electrode connections
- Equipment grounding conductor on 500 A circuits
Two gauge copper carries 95 A at 60°C and 115 A at 75°C. Neither value is a standard rating, so 240.4(B) permits the next standard rating above each: 100 A on the 60°C value and 125 A on the 75°C value, because 240.6(A) steps from 110 A to 125 A with nothing in between. 240.6(A) has no rating between 110 A and 125 A, which is what lets the device sit 10 A above the ampacity.
It is the largest grounding electrode conductor 250.66(C) allows for a ground ring, and Table 250.66 calls for 2 AWG copper on service conductors over 3/0 through 350 kcmil. Table 250.122 makes 2 AWG copper the equipment grounding conductor for a 500 A circuit.
Aluminum at this size lands on a 90 A or a 100 A device where copper lands on a 100 A or a 125 A one, so a feeder that is tight in copper is one trade size larger in aluminum. Aluminum is chosen here when the run is long enough that the price difference pays for the extra size, and the terminations have to be listed for aluminum, with any antioxidant applied as the lug instructions require rather than as a general habit.
Grounding with 2 AWG
As an equipment grounding conductor, 2 AWG is sized from the overcurrent device rather than from the phase conductors. Table 250.122 names 2 AWG copper on the 500 A row and 2 AWG aluminum on the 300 A row. 250.122(B) raises the ground in the same proportion as the phase conductors when they are increased for voltage drop, and 250.122(A) caps it at the size of the conductors it runs with.
As a grounding electrode conductor, 2 AWG appears in Table 250.66, which is sized from the largest ungrounded service conductor rather than from the service rating: copper where the service runs over 3/0 through 350 kcmil, and aluminum where the service runs 4/0 AWG or 250 kcmil. It is the largest grounding electrode conductor 250.66(C) allows for a ground ring.
Voltage drop and run limits
Chapter 9 Table 8 lists 2 AWG copper at 0.194 ohms per 1000 ft at 75°C and aluminum at 0.319 ohms per 1000 ft. Resistance is what a voltage-drop calculation multiplies by current and length, so a conductor twice as long drops twice the volts.
| Conductor | 120 V single phase | 240 V single phase | 240 V three phase |
|---|---|---|---|
| 2 AWG copper at 95 A | 95 ft | 195 ft | 225 ft |
| 2 AWG aluminum at 75 A | 75 ft | 150 ft | 170 ft |
NEC 210.19(A)(1) Informational Note 4 recommends keeping branch-circuit drop at or below 3%. The lengths above are floored to the nearest 5 ft so a listed length never exceeds the computed limit, and they leave reactance out, which makes a large conductor in steel raceway fall short. Halving the current doubles the distance.
Where 2 AWG sits
| Conductor | 60°C | 75°C | 90°C |
|---|---|---|---|
| 3 AWG copper | 85 A | 100 A | 115 A |
| 2 AWG copper | 95 A | 115 A | 130 A |
| 1 AWG copper | 110 A | 130 A | 145 A |
2 AWG questions
- How many amps can 2 gauge wire handle?
- 2 AWG copper handles 95 A at 60°C, 115 A at 75°C, and 130 A at 90°C. No 240.4(D) cap applies at this size, so the breaker follows the column: 100 A at 60°C and 125 A at 75°C. Aluminum at the same size handles 75 A, 90 A, and 100 A.
- What size breaker for 2 gauge wire?
- 100 A on the 60°C column and 125 A on the 75°C column. Where an ampacity falls between standard ratings, 240.4(B) permits the next size up, so 100 A protects the 95 A 60°C ampacity and 125 A protects the 115 A 75°C ampacity. It relaxes the device rather than the conductor, so a load at the full rating still needs the larger size. Aluminum takes 80 A at 60°C and 90 A at 75°C.
- What is 2 gauge wire used for?
- 100 A to 125 A feeders and panel changes; ground rings and grounding electrode connections; equipment grounding conductor on 500 A circuits. Two gauge copper carries 95 A at 60°C and 115 A at 75°C. Neither value is a standard rating, so 240.4(B) permits the next standard rating above each: 100 A on the 60°C value and 125 A on the 75°C value, because 240.6(A) steps from 110 A to 125 A with nothing in between. 240.6(A) has no rating between 110 A and 125 A, which is what lets the device sit 10 A above the ampacity.
- What size ground wire with 2 gauge conductors?
- 2 AWG copper is the equipment grounding conductor for 500 A circuits in Table 250.122, and 2 AWG aluminum is the ground for 300 A circuits. The ground is sized from the overcurrent device rather than from the phase conductors, and 250.122(B) raises it in the same proportion if the phase conductors are increased for voltage drop. It never has to be larger than the conductors it runs with.
- Is 2 gauge a grounding electrode conductor?
- Yes, in one place. 2 AWG copper is the grounding electrode conductor where the service conductors are over 3/0 through 350 kcmil, and 2 AWG aluminum is the grounding electrode conductor where the service conductors are 4/0 AWG or 250 kcmil. It is the largest grounding electrode conductor 250.66(C) allows for a ground ring.
- Is 2 AWG aluminum as good as copper?
- It carries less. In Table 310.16, 2 AWG aluminum is 75 A, 90 A, and 100 A against 95 A, 115 A, and 130 A for copper, so a load that copper serves at this size usually needs one size larger in aluminum. The lugs and devices it lands on have to be listed for aluminum conductors.