NEC Table 310.16
Wire Ampacity Chart (NEC 310.16)
Allowable ampacities for copper and aluminum conductors at 60, 75, and 90°C, straight from NEC Table 310.16. The 75°C column is the one that governs most terminations.
NEC Table 310.16 Ampacity Chart
| Size (AWG / kcmil) | Copper | Aluminum | ||||
|---|---|---|---|---|---|---|
| 60°C | 75°C | 90°C | 60°C | 75°C | 90°C | |
| 14 | 15 | 20 | 25 | — | — | — |
| 12 | 20 | 25 | 30 | 15 | 20 | 25 |
| 10 | 30 | 35 | 40 | 25 | 30 | 35 |
| 8 | 40 | 50 | 55 | 35 | 40 | 45 |
| 6 | 55 | 65 | 75 | 40 | 50 | 55 |
| 4 | 70 | 85 | 95 | 55 | 65 | 75 |
| 3 | 85 | 100 | 115 | 65 | 75 | 85 |
| 2 | 95 | 115 | 130 | 75 | 90 | 100 |
| 1 | 110 | 130 | 145 | 85 | 100 | 115 |
| 1/0 | 125 | 150 | 170 | 100 | 120 | 135 |
| 2/0 | 145 | 175 | 195 | 115 | 135 | 150 |
| 3/0 | 165 | 200 | 225 | 130 | 155 | 175 |
| 4/0 | 195 | 230 | 260 | 150 | 180 | 205 |
| 250 | 215 | 255 | 290 | 170 | 205 | 230 |
| 300 | 240 | 285 | 320 | 195 | 230 | 260 |
| 350 | 260 | 310 | 350 | 210 | 250 | 280 |
| 400 | 280 | 335 | 380 | 225 | 270 | 305 |
| 500 | 320 | 380 | 430 | 260 | 310 | 350 |
| 600 | 350 | 420 | 475 | 285 | 340 | 385 |
| 700 | 385 | 460 | 520 | 315 | 375 | 425 |
| 750 | 400 | 475 | 535 | 320 | 385 | 435 |
| 800 | 410 | 490 | 555 | 330 | 395 | 445 |
| 900 | 435 | 520 | 585 | 355 | 425 | 480 |
| 1000 | 455 | 545 | 615 | 375 | 445 | 500 |
| 1250 | 495 | 590 | 665 | 405 | 485 | 545 |
| 1500 | 525 | 625 | 705 | 435 | 520 | 585 |
| 1750 | 545 | 650 | 735 | 455 | 545 | 615 |
| 2000 | 555 | 665 | 750 | 470 | 560 | 630 |
Aluminum is not listed below 12 AWG because it is not used at those sizes. Copper 60°C insulations are TW and UF; 75°C are THW, THWN, and XHHW (wet); 90°C are THHN, THWN-2, and XHHW-2. The 90°C column is for derating only, never the final termination rating (NEC 110.14(C)).
How to Read the Ampacity Chart
Sizing a conductor is a four-step process. First, size the load: required ampacity = continuous load × 1.25 + noncontinuous load (NEC 210.19(A) and 210.20(A)). Second, pick the column that matches the terminal rating of the equipment. Breakers, lugs, and most equipment are rated 75°C, and NEC 110.14(C)(1) says you must use the ampacity column that matches the lowest-rated termination in the circuit. Third, read down the copper or aluminum block to the first size whose ampacity is at or above your required ampacity. Fourth, if the conductor runs through high ambient temperature or is bundled with more than three current-carrying conductors, start from the 90°C column, apply the correction and adjustment factors from NEC 310.15, and confirm the derated result still lands at or below the 75°C terminal value.
One exception trips people up constantly: the small-conductor rule. NEC 240.4(D) caps overcurrent protection at 15A for 14 AWG copper, 20A for 12 AWG copper, and 30A for 10 AWG copper regardless of the higher table value, and at 15A for 12 AWG aluminum and 25A for 10 AWG aluminum. That is why a 12 AWG copper branch circuit is always on a 20A breaker even though the wire is rated 25A at 75°C.
Worked Examples
Example 1: 60A continuous load at 75°C
Required ampacity = 60A × 1.25 = 75A
Reading the copper 75°C column, #4 is 85A (the first size at or above 75A), so use #4 copper. In aluminum, #3 is 75A exactly, so #3 aluminum also works. Both are protected at the next standard breaker size, 80A per NEC 240.6(A).
Example 2: #6 copper THHN in a 108°F attic
Start at 90°C: #6 Cu = 75A. Temp correction at 105-113°F = 0.87 (NEC 310.15(B)(1))
75A × 0.87 = 65.25A
The derated ampacity is 65A, which happens to equal the 75°C termination value for #6 copper. Starting from the 90°C column is what lets #6 still carry a 60A load in a hot attic, but the final answer can never exceed the 75°C terminal rating.
Frequently Asked Questions
What is the ampacity of #6 copper wire?
The ampacity of #6 copper wire is 65A at the 75°C column of NEC Table 310.16, which is the value used for most terminations. It is 55A at 60°C and 75A at 90°C. The 90°C value is only for derating math, never for the final termination rating, per NEC 110.14(C).
What size wire do I need for 100 amps?
For a 100A load, use #3 copper or #1 aluminum at the 75°C column of NEC Table 310.16 (#3 Cu is 100A, #1 Al is 100A). For a 100A dwelling service or feeder that carries the full load of the dwelling, NEC 310.12 allows #4 copper or #2 aluminum instead.
What size wire for a 200 amp service?
A 200A service normally uses 3/0 copper or 250 kcmil aluminum at 75°C per NEC Table 310.16. For a dwelling service or main feeder carrying the entire load of a one-family dwelling, NEC 310.12 permits 2/0 copper or 4/0 aluminum.
What is the ampacity of 12 gauge wire?
#12 copper is rated 25A at 75°C in NEC Table 310.16, but the small-conductor rule in NEC 240.4(D)(5) limits its overcurrent protection to 20A. #12 aluminum is 20A at 75°C and is limited to 15A by 240.4(D)(4). That is why a 12 AWG copper circuit is protected at 20A even though the wire is rated higher.
What is the difference between the 60, 75, and 90 degree columns?
The columns are the insulation temperature rating. 60°C is for TW and UF, 75°C is for THW, THWN, and XHHW in wet locations, and 90°C is for THHN, THWN-2, and XHHW-2. Use the column that matches the lowest-rated part of the circuit, which is almost always the 75°C terminal rating on breakers and lugs per NEC 110.14(C).
Can I use the 90 degree column for ampacity?
No, not for the final rating. The 90°C column is only a starting point for derating (ambient temperature and bundling adjustments) per NEC 110.14(C)(1). After derating you must still land at or below the 60°C or 75°C terminal rating of the equipment, which for most breakers and lugs is 75°C.
Is aluminum wire one size larger than copper?
Roughly, yes. At the 75°C column aluminum carries about one to two AWG sizes less current than the same-size copper. For example #2 copper is 115A and #2 aluminum is 90A, so you step up to #1/0 aluminum (120A) to match #2 copper. Always confirm against the exact NEC 310.16 value rather than a rule of thumb.
Related Calculators & Charts
Wire Size Calculator
Enter load, distance, and conditions to get the exact conductor size with voltage drop and derating handled, using this same NEC 310.16 data.
Voltage Drop Calculator
Check the run distance where voltage drop, not ampacity, sets your wire size. Both constraints must pass.
Conduit Fill Calculator
Once the wire is sized, confirm the conductors fit the raceway per NEC Chapter 9 at the 40 percent fill limit.
Know the ampacity. Now size the actual run.
Ampacity is only half the job. On a long run, voltage drop can force a larger conductor than the table requires. The wire size calculator checks both against NEC 310.16 and gives you the governing size.