Reference chart

Wire Ampacity Chart

Base allowable ampacities for copper and aluminum conductors at 60°C, 75°C and 90°C. These are the starting values — apply the ambient and raceway corrections with the ampacity calculator, or find the right size directly with the wire size calculator, or see the wire size chart for circular-mil areas and typical circuit sizes.

How to read this chart

There is one ampacity per conductor per temperature column, and the column is set by the weakest link in the circuit — not by the conductor alone. The 90°C column is the insulation's own limit, so it applies only when the terminations are also rated 90°C. Equipment rated 100 A or less defaults to the 60°C column unless it is marked 75°C. Equipment over 100 A defaults to 75°C. A 90°C THHN conductor is governed by whichever of those columns the terminals require, not automatically by the 75°C column (NEC 110.14(C)).

Two corrections then move the number. Ambient temperature correction (NEC Table 310.15(B)(1)(1)) is applied when the surrounding air is not the 30°C the table assumes. The adjustment for more than three current-carrying conductors in a raceway (NEC 310.15(C)(1)) is applied when conductors share a raceway. The circuit may use the smaller of the corrected ampacity and the termination column.

Sizes of 250 kcmil and above are also written MCM in older references: 500 kcmil and 500 MCM are the same conductor, and 750 MCM is the same as 750 kcmil.

Copper

Size	60°C	75°C	90°C
14 AWG	15 A	20 A	25 A
12 AWG	20 A	25 A	30 A
10 AWG	30 A	35 A	40 A
8 AWG	40 A	50 A	55 A
6 AWG	55 A	65 A	75 A
4 AWG	70 A	85 A	95 A
3 AWG	85 A	100 A	115 A
2 AWG	95 A	115 A	130 A
1 AWG	110 A	130 A	145 A
1/0 AWG	125 A	150 A	170 A
2/0 AWG	145 A	175 A	195 A
3/0 AWG	165 A	200 A	225 A
4/0 AWG	195 A	230 A	260 A
250 kcmil	215 A	255 A	290 A
300 kcmil	240 A	285 A	320 A
350 kcmil	260 A	310 A	350 A
400 kcmil	280 A	335 A	380 A
500 kcmil	320 A	380 A	430 A
600 kcmil	350 A	420 A	475 A
750 kcmil	400 A	475 A	535 A
1000 kcmil	455 A	545 A	615 A

Aluminum

Size	60°C	75°C	90°C
12 AWG	15 A	20 A	25 A
10 AWG	25 A	30 A	35 A
8 AWG	35 A	40 A	45 A
6 AWG	40 A	50 A	55 A
4 AWG	55 A	65 A	75 A
3 AWG	65 A	75 A	85 A
2 AWG	75 A	90 A	100 A
1 AWG	85 A	100 A	115 A
1/0 AWG	100 A	120 A	135 A
2/0 AWG	115 A	135 A	150 A
3/0 AWG	130 A	155 A	175 A
4/0 AWG	150 A	180 A	205 A
250 kcmil	170 A	205 A	230 A
300 kcmil	195 A	230 A	260 A
350 kcmil	210 A	250 A	280 A
400 kcmil	225 A	270 A	305 A
500 kcmil	260 A	310 A	350 A
600 kcmil	285 A	340 A	385 A
750 kcmil	320 A	385 A	435 A
1000 kcmil	375 A	445 A	500 A

Aluminum conductor ampacity for common sizes

Aluminum is not a drop-in replacement for copper. At the same size it carries less current, so an aluminum run is usually one or two standard sizes larger than the copper run it replaces. Terminations must be listed for aluminum, and small branch-circuit sizes are commonly restricted, which is why aluminum shows up on service conductors, feeders and large feeders far more often than on 15 A or 20 A branch circuits.

Size	75°C	90°C
6 AWG	50 A	55 A
4 AWG	65 A	75 A
2 AWG	90 A	100 A
1/0 AWG	120 A	135 A
2/0 AWG	135 A	150 A
4/0 AWG	180 A	205 A
250 kcmil	205 A	230 A
350 kcmil	250 A	280 A
500 kcmil	310 A	350 A
750 kcmil	385 A	435 A

Base values only. Apply the same ambient and conductor-count corrections as copper, then compare against the termination rating: a 90°C aluminum conductor on a 75°C lug is still limited to the 75°C column.

Values reflect NEC 2023 and are pending review; the 2026 edition has not been verified. Verify before relying on them for construction.