Table 310.81 Ampacities of Single Insulated Copper Conductors Directly Buried in Earth Based on Ambient Earth Temperature of 20°C (68°F), Arrangement per Figure 310.60, 100 Percent Load Factor, Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°C (194°F) and 105°C (221°C)
| Conductor Size (AWG or kcmil) | Temperature Rating of Conductor | |||
| 2001 - 5000 Volts Ampacity | 5001 - 35,000 Volts Ampacity | |||
| 90°C (194°F) Type MV-90 | 105°C (221°F) Type MV-105 | 90°C (194°F) Type MV-90 | 105°C (221°F) Type MV-105 | |
| One Circuit, Three Conductors (See Figure 310.60, Detail 9.) | ||||
| 8 | 110 | 115 | – | – |
| 6 | 140 | 150 | 130 | 140 |
| 4 | 180 | 195 | 170 | 180 |
| 2 | 230 | 250 | 210 | 225 |
| 1 | 260 | 280 | 240 | 260 |
| 1/0 | 295 | 320 | 275 | 295 |
| 2/0 | 335 | 365 | 310 | 335 |
| 3/0 | 385 | 415 | 355 | 380 |
| 4/0 | 435 | 465 | 405 | 435 |
| 250 | 470 | 510 | 440 | 475 |
| 350 | 570 | 615 | 535 | 575 |
| 500 | 690 | 745 | 650 | 700 |
| 750 | 845 | 910 | 805 | 865 |
| 1000 | 980 | 1055 | 930 | 1005 |
| Two Circuits, Six Conductors (See Figure 310.60, Detail 10.) | ||||
| 8 | 100 | 110 | – | – |
| 6 | 130 | 140 | 120 | 130 |
| 4 | 165 | 180 | 160 | 170 |
| 2 | 215 | 230 | 195 | 210 |
| 1 | 240 | 260 | 225 | 240 |
| 1/0 | 275 | 295 | 255 | 275 |
| 2/0 | 310 | 335 | 290 | 315 |
| 3/0 | 355 | 380 | 330 | 355 |
| 4/0 | 400 | 430 | 375 | 405 |
| 250 | 435 | 470 | 410 | 440 |
| 350 | 520 | 560 | 495 | 530 |
| 500 | 630 | 680 | 600 | 645 |
| 750 | 775 | 835 | 740 | 795 |
| 1000 | 890 | 960 | 855 | 920 |
Table 310.83 Ampacities of Three Insulated Copper Conductors Cabled Within an Overall Covering (Three-Conductor Cable), Directly Buried in Earth Based on Ambient Earth Temperature of 20°C (68°F), Arrangement per Figure 310.60, 100 Percent Load Factor, Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°C (194°F) and 105°C (221°F)
| Conductor Size (AWG or kcmil) | Temperature Rating of Conductor | |||
| 2001 - 5000 Volts Ampacity | 5001 - 35,000 Volts Ampacity | |||
| 90°C (194°F) Type MV-90 | 105°C (221°F) Type MV-105 | 90°C (194°F) Type MV-90 | 105°C (221°F) Type MV-105 | |
| One Circuit (See Figure 310.60, Detail 1.) | ||||
| 8 | 85 | 89 | – | – |
| 6 | 105 | 115 | 115 | 120 |
| 4 | 135 | 150 | 145 | 155 |
| 2 | 180 | 190 | 185 | 200 |
| 1 | 200 | 215 | 210 | 225 |
| 1/0 | 230 | 245 | 240 | 255 |
| 2/0 | 260 | 280 | 270 | 290 |
| 3/0 | 295 | 320 | 305 | 330 |
| 4/0 | 335 | 360 | 350 | 375 |
| 250 | 365 | 395 | 380 | 410 |
| 350 | 440 | 475 | 460 | 495 |
| 500 | 530 | 570 | 550 | 590 |
| 750 | 650 | 700 | 665 | 720 |
| 1000 | 730 | 785 | 750 | 810 |
| Two Circuits (See Figure 310.60, Detail 10.) | ||||
| 8 | 80 | 84 | – | – |
| 6 | 100 | 105 | 105 | 115 |
| 4 | 130 | 140 | 135 | 145 |
| 2 | 165 | 180 | 170 | 185 |
| 1 | 185 | 200 | 195 | 210 |
| 1/0 | 215 | 230 | 220 | 235 |
| 2/0 | 240 | 260 | 250 | 270 |
| 3/0 | 275 | 295 | 280 | 305 |
| 4/0 | 310 | 335 | 320 | 345 |
| 250 | 340 | 365 | 350 | 375 |
| 350 | 410 | 440 | 420 | 450 |
| 500 | 490 | 525 | 500 | 535 |
| 750 | 595 | 640 | 605 | 650 |
| 1000 | 665 | 715 | 675 | 730 |