Aluminum Conductor Ampacity Table

NEC 2023Every value in this table is transcribed from the 2023 NEC (NFPA 70, 2023). The code is republished on a three-year cycle and adoption varies by jurisdiction - confirm against your locally adopted edition and your authority having jurisdiction (AHJ) before you build.

Allowable ampacity of insulated aluminum conductors rated up to 2000 V, with not more than three current-carrying conductors in a raceway, cable, or earth, based on an ambient temperature of 30°C (86°F). The final column is the separate small-conductor overcurrent ceiling, which applies regardless of the ampacity shown.
Size	60°C	75°C	90°C	Overcurrent cap
12 AWG	15	20	25	15 A
10 AWG	25	30	35	25 A
8 AWG	35	40	45	-
6 AWG	40	50	55	-
4 AWG	55	65	75	-
3 AWG	65	75	85	-
2 AWG	75	90	100	-
1 AWG	85	100	115	-
1/0 AWG	100	120	135	-
2/0 AWG	115	135	150	-
3/0 AWG	130	155	175	-
4/0 AWG	150	180	205	-
250 kcmil	170	205	230	-
300 kcmil	195	230	260	-
350 kcmil	210	250	280	-
400 kcmil	225	270	305	-
500 kcmil	260	310	350	-
600 kcmil	285	340	385	-
700 kcmil	315	375	425	-
750 kcmil	320	385	435	-
800 kcmil	330	395	445	-
900 kcmil	355	425	480	-
1000 kcmil	375	445	500	-
1250 kcmil	405	485	545	-
1500 kcmil	435	520	585	-
1750 kcmil	455	545	615	-
2000 kcmil	470	560	630	-

Source: NFPA 70, National Electrical Code, Table 310.16; NFPA 70, National Electrical Code, 240.4(D). Published by NFPA.NEC 2023Transcribed from the 2023 NEC (NFPA 70, 2023). Confirm against your locally adopted edition and your authority having jurisdiction (AHJ).

Reading this table

The three temperature columns are the conductor's insulation rating, not the ambient temperature. A 90°C-rated conductor is not permitted to run hotter than the equipment it terminates on allows - and most breakers and equipment are listed for 60°C or 75°C. In practice the 75°C column governs most installations, and the 90°C column is used as the starting point for derating rather than as a final ampacity.

The overcurrent cap column

The smallest conductors carry a fixed protection ceiling that is separate from ampacity. It exists because small conductors have little thermal mass and are easily damaged, and it applies regardless of what the temperature columns read. The cited section carries specific exceptions this table does not reproduce.

Aluminum specifics

Aluminum is not listed at 14 AWG. Compared with copper of the same size it carries less current and has higher resistance, so aluminum runs need larger conductors and drop more voltage over the same distance. It also requires terminations listed for aluminum and an antioxidant compound at connections - the corrosion and creep failures aluminum is remembered for are largely termination failures.

Before you use these numbers

Correct for ambient temperature and adjust for the number of current-carrying conductors before sizing anything - see the temperature correction and bundling adjustment tables, or let the ampacity lookup apply both.

Copper ampacity Temperature correction Bundling adjustment Breaker sizes Grounding conductors Conduit fill Conductor properties

FAQ

Frequently asked questions

Which temperature column should I use?

The three temperature columns are the conductor's insulation rating, not the ambient temperature, and a conductor is not permitted to run hotter than the equipment it terminates on allows. Most breakers and equipment are listed for 60°C or 75°C, so in practice the 75°C column governs most installations and the 90°C column is used as the starting point for derating rather than as a final ampacity.

Does the 80 percent rule apply to these ampacities?

Not to the table values themselves - they are allowable ampacities at a 30°C ambient with no more than three current-carrying conductors. Continuous loading is handled separately: a load that runs three hours or more is sized at 125 percent, which is the same arithmetic as loading the circuit to 80 percent. The smallest conductors also carry a fixed overcurrent cap that applies regardless of what the temperature columns read.

When does aluminum need upsizing?

Compared with copper of the same size, aluminum carries less current and has higher resistance, so aluminum runs need larger conductors and drop more voltage over the same distance. Aluminum is not listed at 14 AWG, and it requires terminations listed for aluminum plus an antioxidant compound at connections.