Table 310.16 is one of the most commonly used tables in the National Electrical Code. The reason is the inherent practicality and breadth of installations covered by “…Insulated Conductors with Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried)”. Note: a neutral is a current-carrying conductor while the grounding conductor(s) are not.
Table 310.16 is applicable up to 2,000 volts with an ambient temperature of 30°C (86°C). Adjustments for temperatures above or below 30°C can be found in NEC Table 310.15(B)(1). Tabulated AC voltage drop calculations for quick reference can be found here: Alternating Current Voltage Drop Calculation Table, or calculate the exact voltage drop here: AC Voltage Drop Calculator.
Pay close attention to the table notes, they are critical to proper application of Table 310.16.
NEC Table 310.16 Copper
| Size AWG or kcmil | 60°C (140°F) | 75°C (167°F) | 90°C (194°F) | |
|---|---|---|---|---|
| Types TW, UF | Types RHW, THHW, THW, THWN, XHHW, XHWN, USE, ZW | Types TBS, SA, SIS, FEP, FEPB, MI, PFA, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, XHWN, XHWN-2, XHHN, Z, ZW-2 | ||
| 18* | — | — | 14 | |
| 16* | — | — | 18 | |
| 14* | 15 | 20 | 25 | |
| 12* | 20 | 25 | 30 | |
| 10* | 30 | 35 | 40 | |
| 8 | 40 | 50 | 55 | |
| 6 | 55 | 65 | 75 | |
| 4 | 70 | 85 | 95 | |
| 3 | 85 | 100 | 115 | |
| 2 | 95 | 115 | 130 | |
| 1 | 110 | 130 | 145 | |
| 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 | |
| 600 | 350 | 420 | 475 | |
| 700 | 385 | 460 | 520 | |
| 750 | 400 | 475 | 535 | |
| 800 | 410 | 490 | 555 | |
| 900 | 435 | 520 | 585 | |
| 1000 | 455 | 545 | 615 | |
| 1250 | 495 | 590 | 665 | |
| 1500 | 525 | 625 | 705 | |
| 1750 | 545 | 650 | 735 | |
| 2000 | 555 | 665 | 750 |
NEC Table 310.16 Aluminum or Copper-Clad Aluminum
| Size AWG or kcmil | 60°C (140°F) | 75°C (167°F) | 90°C (194°F) | |
|---|---|---|---|---|
| Types TW, UF | Types RHW, THHW, THW, THWN, XHHW, XHWN, USE | Types TBS, SA, SIS, THHN, THHW, THW-2, THWN-2, RHH, RHW-2, USE-2, XHH, XHHW, XHHW-2, XHWN, XHWN-2, XHHN | ||
| 12* | 15 | 20 | 25 | |
| 10* | 25 | 30 | 35 | |
| 8 | 35 | 40 | 45 | |
| 6 | 40 | 50 | 55 | |
| 4 | 55 | 65 | 75 | |
| 3 | 65 | 75 | 85 | |
| 2 | 75 | 90 | 100 | |
| 1 | 85 | 100 | 115 | |
| 1/0 | 100 | 120 | 135 | |
| 2/0 | 115 | 135 | 150 | |
| 3/0 | 130 | 155 | 175 | |
| 4/0 | 150 | 180 | 205 | |
| 250 | 170 | 205 | 230 | |
| 300 | 195 | 230 | 260 | |
| 350 | 210 | 250 | 280 | |
| 400 | 225 | 270 | 305 | |
| 500 | 260 | 310 | 350 | |
| 600 | 285 | 340 | 385 | |
| 700 | 315 | 375 | 425 | |
| 750 | 320 | 385 | 435 | |
| 800 | 330 | 395 | 445 | |
| 900 | 355 | 425 | 480 | |
| 1000 | 375 | 445 | 500 | |
| 1250 | 405 | 485 | 545 | |
| 1500 | 435 | 520 | 585 | |
| 1750 | 455 | 545 | 615 | |
| 2000 | 470 | 560 | 630 |
Table Notes:
- Section 310.15(B) shall be referenced for ampacity correction factors where the ambient temperature is other than 30°C (86°F).
- Section 310.15(C)(1) shall be referenced for more than three current-carrying conductors.
- Section 310.16 shall be referenced for conditions of use.
- * Section 240.4(D) shall be referenced for conductor overcurrent protection limitations, except as modified elsewhere in the Code.
Source: NFPA 70