Wire Ampacity Chart (NEC Table 310.16)

Ampacity is the maximum continuous current a conductor can carry without exceeding its temperature rating. These values are from NEC Table 310.16 for conductors in raceway, cable, or direct burial, with up to 3 current-carrying conductors, at 30°C (86°F) ambient. Derate for higher ambient temperatures or more conductors in conduit.

Ampacity Table

Gauge	Cu 60°C	Cu 75°C	Cu 90°C	Al 75°C	Al 90°C
14 AWG	15	20	25	-	-
12 AWG	20	25	30	25	30
10 AWG	30	35	40	30	35
8 AWG	40	50	55	40	45
6 AWG	55	65	75	50	60
4 AWG	70	85	95	65	75
3 AWG	85	100	110	75	85
2 AWG	95	115	130	90	100
1 AWG	110	130	150	100	115
1/0 AWG	125	150	170	120	135
2/0 AWG	145	175	195	135	150
3/0 AWG	165	200	225	155	175
4/0 AWG	195	230	260	180	205
250 kcmil	215	255	290	205	230
300 kcmil	240	285	320	230	255
350 kcmil	260	310	350	250	280
400 kcmil	280	335	380	270	305
500 kcmil	320	380	430	310	350

Approximate values from NEC Table 310.16. Always verify with the current NEC edition.

Ambient Temperature Correction Factors (NEC Table 310.15(B))

Multiply the table ampacity by the correction factor for your actual ambient temperature.

Ambient Temp (°C)	Ambient Temp (°F)	60°C Factor	75°C Factor	90°C Factor
10°C	50°F	1.29	1.20	1.15
15°C	59°F	1.22	1.15	1.12
20°C	68°F	1.15	1.11	1.08
25°C	77°F	1.08	1.05	1.04
30°C	86°F	1.00	1.00	1.00
35°C	95°F	0.91	0.94	0.96
40°C	104°F	0.82	0.88	0.91
45°C	113°F	0.71	0.82	0.87
50°C	122°F	0.58	0.75	0.82
55°C	131°F	0.41	0.67	0.76
60°C	140°F	N/A	0.58	0.71

30°C row (highlighted) is the base case (factor = 1.00). Approx. from NEC Table 310.15(B).

Conduit Fill Derating (NEC Table 310.15(C)(1))

When 4 or more current-carrying conductors share a raceway, cable, or are bundled together, multiply the ampacity by the factor below.

Number of Current-Carrying Conductors	Ampacity Adjustment Factor
4-6 conductors	80%
7-9 conductors	70%
10-20 conductors	50%
21-30 conductors	45%
31-40 conductors	40%
41+ conductors	35%

Neutral conductors carrying only unbalanced load are not counted. Equipment grounding conductors are never counted. Source: NEC Table 310.15(C)(1), approx.