How many amps can 12 AWG copper carry?

12 AWG copper is 20 A at 60°C, 25 A at 75°C, and 30 A at 90°C in NEC Table 310.16, before any derating. NEC 240.4(D) separately caps overcurrent protection for 12 AWG copper at 20 A regardless of insulation, which is why 12 AWG copper lands on a 20 A breaker in most branch circuits. The 90°C figure is a derating starting point, not a usable circuit rating.

Which temperature column do I use?

The column is the conductor insulation rating: TW is 60°C, THW and THWN are 75°C, THHN, THWN-2 and XHHW-2 are 90°C. You may start derating from the conductor insulation column, but NEC 110.14(C) then caps the final ampacity at the termination temperature rating, which is 60°C or 75°C on most equipment. In practice the 75°C column governs most terminations, and the 90°C column mainly buys derating headroom.

Are these ampacities the final usable values?

No. These are the base Table 310.16 ampacities at 30°C (86°F) ambient with three or fewer current-carrying conductors. Real installations multiply by the ambient correction factor (Table 310.15(B)(1)) and the more-than-three-conductors adjustment (Table 310.15(C)(1)), then apply the 110.14(C) termination cap. The Wire Ampacity Calculator does all three steps.

Do the values change between NEC 2017, 2020, and 2023?

No. The Table 310.16 cell values are identical across the 2017, 2020, and 2023 editions. The only change was the table designation: it was Table 310.15(B)(16) in 2017 and became Table 310.16 in 2020. So this single chart is correct for all three editions.

Why do 18 and 16 AWG copper show a value only at 90°C?

NEC Table 310.16 lists 18 and 16 AWG copper with a 90°C value only (14 A and 18 A); their 60°C and 75°C cells are blank in the NEC table, which is why this chart shows a dash there. Those two sizes are fixture wires, not general branch-circuit conductors, and NEC 240.4(D) caps their overcurrent protection at 7 A and 10 A regardless of ampacity. From 14 AWG up, all three columns are populated, and the 240.4(D) small-conductor limits (15, 20, and 30 A for 14, 12, and 10 AWG copper) are in the footnotes.

Wire Ampacity Chart

Name: Wire Ampacity Chart: NEC Table 310.16 base ampacities
Creator: ElectricalToolbox
License: https://electricaltoolbox.com/terms

Base allowable ampacities from NEC Table 310.16 for copper and aluminum conductors, in the 60°C, 75°C, and 90°C insulation columns, from 18 AWG through 2000 kcmil. Every value is computed with the same data as our Wire Ampacity Calculator, so the chart cannot drift from the tool. Print it, or use the calculator when derating applies.

Copper conductors

Base ampacity (A) at 30°C (86°F) ambient, three or fewer current-carrying conductors, before derating. "-" means the NEC lists no value in that column.

AWG/kcmil	60°C	75°C	90°C
18	-	-	14 A
16	-	-	18 A
14	15 A	20 A	25 A
12	20 A	25 A	30 A
10	30 A	35 A	40 A
8	40 A	50 A	55 A
6	55 A	65 A	75 A
4	70 A	85 A	95 A
3	85 A	100 A	115 A
2	95 A	115 A	130 A
1	110 A	130 A	145 A
1/0	125 A	150 A	170 A
2/0	145 A	175 A	195 A
3/0	165 A	200 A	225 A
4/0	195 A	230 A	260 A
250	215 A	255 A	290 A
300	240 A	285 A	320 A
350	260 A	310 A	350 A
400	280 A	335 A	380 A
500	320 A	380 A	430 A
600	350 A	420 A	475 A
700	385 A	460 A	520 A
750	400 A	475 A	535 A
800	410 A	490 A	555 A
900	435 A	520 A	585 A
1000	455 A	545 A	615 A
1250	495 A	590 A	665 A
1500	525 A	625 A	705 A
1750	545 A	650 A	735 A
2000	555 A	665 A	750 A

Aluminum conductors

Base ampacity (A) at 30°C (86°F) ambient, three or fewer current-carrying conductors, before derating. "-" means the NEC lists no value in that column.

AWG/kcmil	60°C	75°C	90°C
12	15 A	20 A	25 A
10	25 A	30 A	35 A
8	30 A	40 A	45 A
6	40 A	50 A	55 A
4	55 A	65 A	75 A
3	65 A	75 A	85 A
2	75 A	90 A	100 A
1	85 A	100 A	115 A
1/0	100 A	120 A	135 A
2/0	115 A	135 A	150 A
3/0	130 A	155 A	175 A
4/0	150 A	180 A	205 A
250	170 A	205 A	230 A
300	195 A	230 A	260 A
350	210 A	250 A	280 A
400	225 A	270 A	305 A
500	260 A	310 A	350 A
600	285 A	340 A	385 A
700	315 A	375 A	425 A
750	320 A	385 A	435 A
800	330 A	395 A	445 A
900	355 A	425 A	480 A
1000	375 A	445 A	500 A
1250	405 A	485 A	545 A
1500	435 A	520 A	585 A
1750	455 A	545 A	615 A
2000	470 A	560 A	630 A

Footnotes. Column headers by common insulation: 60°C = TW; 75°C = THW, THWN; 90°C = THHN, THWN-2, XHHW-2. Copper 18 and 16 AWG carry a 90°C value only (fixture wire). NEC 240.4(D) small-conductor overcurrent limits still apply regardless of ampacity: copper 18 AWG 7 A, 16 AWG 10 A, 14 AWG 15 A, 12 AWG 20 A, 10 AWG 30 A; aluminum 12 AWG 15 A, 10 AWG 25 A.

How to use this chart

Pick the copper or aluminum table to match your conductor material.
Read down to your conductor size (AWG or kcmil).
Read across to the column for your insulation rating: 60°C, 75°C, or 90°C.
Apply the NEC 110.14(C) termination limit: use the lower of the insulation column and the equipment termination rating (usually 75°C) as the governing value.
If ambient exceeds 30°C or more than three current-carrying conductors share the raceway, derate with the Wire Ampacity Calculator.

NEC reference

Values are the base allowable ampacities of NEC 2020 Table 310.16 (allowable ampacities of insulated conductors rated 0 to 2000 V, 60°C through 90°C, not more than three current-carrying conductors in a raceway, cable, or earth, based on 30°C ambient). The same cell values apply in NEC 2017 (where the table was numbered 310.15(B)(16)) and NEC 2023. Ambient correction is Table 310.15(B)(1); the more-than-three-conductors adjustment is Table 310.15(C)(1); the termination temperature limit is NEC 110.14(C); and the small-conductor overcurrent limits are NEC 240.4(D).

Results are for reference only. Verify against the applicable adopted edition of the NEC and consult a licensed electrician for code compliance.

Base ampacity vs. usable ampacity

The numbers here are the starting point, not the answer for a specific installation. Table 310.16 assumes a 30°C (86°F) ambient and three or fewer current-carrying conductors. Two adjustments can lower the value: the ambient correction factor from Table 310.15(B)(1) when the conductor runs hotter than 30°C, and the adjustment factor from Table 310.15(C)(1) when four or more current-carrying conductors share a raceway or cable. Both factors multiply.

Then NEC 110.14(C) caps the result at the temperature rating of the weakest termination in the circuit. Most breakers, lugs, and devices are rated 75°C (some 60°C on 100 A and smaller equipment), so even a 90°C conductor is usually limited to its 75°C ampacity at the terminations. The Wire Ampacity Calculator runs all three steps and reports which one governs.

Common sizes at a glance

At the 75°C column, the sizes electricians reach for most: 14 AWG copper is 20 A, 12 AWG copper 25 A, 10 AWG copper 35 A, 8 AWG copper 50 A, 6 AWG copper 65 A, and 4 AWG copper 85 A. In aluminum at 75°C: 2 AWG is 90 A, 1/0 is 120 A, 2/0 is 135 A, and 4/0 is 180 A, the common 200 A dwelling-service pairing when taken with 310.12 (not shown on this base chart). Remember the 240.4(D) small-conductor rule holds 14, 12, and 10 AWG copper to 15, 20, and 30 A breakers even though the table shows more.

Frequently asked questions

How many amps can 12 AWG copper carry?: 12 AWG copper is 20 A at 60°C, 25 A at 75°C, and 30 A at 90°C in NEC Table 310.16, before any derating. NEC 240.4(D) separately caps overcurrent protection for 12 AWG copper at 20 A regardless of insulation, which is why 12 AWG copper lands on a 20 A breaker in most branch circuits. The 90°C figure is a derating starting point, not a usable circuit rating.
Which temperature column do I use?: The column is the conductor insulation rating: TW is 60°C, THW and THWN are 75°C, THHN, THWN-2 and XHHW-2 are 90°C. You may start derating from the conductor insulation column, but NEC 110.14(C) then caps the final ampacity at the termination temperature rating, which is 60°C or 75°C on most equipment. In practice the 75°C column governs most terminations, and the 90°C column mainly buys derating headroom.
Are these ampacities the final usable values?: No. These are the base Table 310.16 ampacities at 30°C (86°F) ambient with three or fewer current-carrying conductors. Real installations multiply by the ambient correction factor (Table 310.15(B)(1)) and the more-than-three-conductors adjustment (Table 310.15(C)(1)), then apply the 110.14(C) termination cap. The Wire Ampacity Calculator does all three steps.
Do the values change between NEC 2017, 2020, and 2023?: No. The Table 310.16 cell values are identical across the 2017, 2020, and 2023 editions. The only change was the table designation: it was Table 310.15(B)(16) in 2017 and became Table 310.16 in 2020. So this single chart is correct for all three editions.
Why do 18 and 16 AWG copper show a value only at 90°C?: NEC Table 310.16 lists 18 and 16 AWG copper with a 90°C value only (14 A and 18 A); their 60°C and 75°C cells are blank in the NEC table, which is why this chart shows a dash there. Those two sizes are fixture wires, not general branch-circuit conductors, and NEC 240.4(D) caps their overcurrent protection at 7 A and 10 A regardless of ampacity. From 14 AWG up, all three columns are populated, and the 240.4(D) small-conductor limits (15, 20, and 30 A for 14, 12, and 10 AWG copper) are in the footnotes.

Related tools

Wire Ampacity Calculator: derated ampacity for your exact ambient, conductor count, and terminations.
Wire Gauge Calculator: minimum AWG for a required ampacity, with full derating.
Wire Size Calculator: ampacity and voltage drop together in one answer.
AWG Calculator: AWG and kcmil to mm² conversions from NEC Chapter 9 Table 8.

Studying for the licensing exam? Our own NEC Code Quickstart works all twelve exam calculations start to finish, each with the code reference. Also in paperback.

Running an electrical contracting business? Jobber handles scheduling, invoicing, and job management. Start a 14-day free trial.

For deeper NEC training on conductors and ampacity, Mike Holt's NEC courses are the industry standard.

Working from the printed code? NEC code books and tab sets are available from Mike Holt.

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