Conductor Ampacity of CU

As a solar system is designed you need to select the correct size conductor. The following tables will help in that selection. This information is based on the following:

• National Electric Code (NEC) Table 310.16
• Conductors rated 0 to 2000 V
• Not more than 3 current carrying conductors in raceway, cable or direct buried
• Ambient Temp 30C (86F)

Allowable Ampacity of Copper Conductors

Size AWG or kcmil	Conductor Temp 60C (140F)	Conductor Temp 75C (167F)	Conductor Temp 90C (194F)
14*	20	20	25
12*	25	25	30
10*	30	35	40
8	40	50	55
6	55	65	75
4	70	85	95
3	85	100	110
2	95	115	130
1	110	130	150
1/0	125	150	170
2/0	145	175	195
3/0	165	200	225
4/0	195	230	260
250	215	255	290
300	240	285	320
350	260	310	350
400	280	335	380
500	320	380	430

14 AWG Maximum overcurrent = 15 amps
12 AWG Maximum overcurrent = 20 amps
10 AWG Maximum overcurrent = 30 amps

Correction Factors for Different Ambient Temperatures

For ambient temperatures other than 30C (86F) the following are multipliers used to adjust the above ampacity.  As the temperature of a conductor increases the amount of current the conductor can safety carry is reduced.

Ambient Temperature (C)	Conductor Temp 60C (140F)	Conductor Temp 75C (167F)	Conductor Temp 90C (194F)	Ambient Temperature (F)
21-25	1.08	1.05	1.04	70-77
26-30	1.00	1.00	1.00	78-86
31-35	0.91	0.94	0.96	87-95
36-40	0.82	0.88	0.91	96-104
41-45	0.71	0.82	0.87	105-113
46-50	0.58	0.75	0.82	114-122
51-55	0.41	0.67	0.76	123-131
56-60	0	0.58	0.71	132-140
61-70	0	0.33	0.58	141-158
71-80	0	0	0.41	159-179