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 kcmilConductor Temp
60C (140F)
Conductor Temp
75C (167F)
Conductor Temp
90C (194F)
14*202025
12*252530
10*303540
8405055
6556575
4708595
385100110
295115130
1110130150
1/0125150170
2/0145175195
3/0165200225
4/0195230260
250215255290
300240285320
350260310350
400280335380
500320380430

*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)
21-251.081.051.0470-77
26-301.001.001.0078-86
31-350.910.940.9687-95
36-400.820.880.9196-104
41-450.710.820.87105-113
46-500.580.750.82114-122
51-550.410.670.76123-131
56-6000.580.71132-140
61-7000.330.58141-158
71-80000.41159-179