Table B. 310.1 Ampacities of Two or Three Insulated Conductors, Rated 0 Through 2000 Volts, Within an Overall Covering (Multiconductor Cable), in Raceway in Free Air Based on Ambient Air Temperature of 30° C (86° F)
| (AWG or kcmil) | Temperature Rating of Conductor. | (AWG or kcmil) | |||||
| 60°C (140°F) |
75°C (167°F) |
90°C (194°F) |
60°C (140°F) |
75°C (167°F) |
90°C (194°F) |
||
| Types TW, UF | Types RHW, THHW, THW, THWN, XHHW, ZW | Types THHN, THHW, THW-2, THWN-2, RHH, RWH-2, USE-2, XHHW, XHHW-2, ZW-2 | Type TW | Types RHW, THHW, THW, THWN, XHHW | Types RHW, THHW, THW, THWN, RHH, RWH-2, USE-2, XHHW, XHHW-2, ZW-2 | ||
| COPPER | ALUMINUM OR COPPER-CLAD ALUMINUM | ||||||
| 14 | 16* | 18* | 21* | – | – | – | 14 |
| 12 | 20* | 24* | 27* | 16* | 18* | 21* | 12 |
| 10 | 27* | 33* | 36* | 21* | 25* | 28* | 10 |
| 8 | 36 | 43 | 48 | 28 | 33 | 37 | 8 |
| 6 | 48 | 58 | 65 | 38 | 45 | 51 | 6 |
| 4 | 66 | 79 | 89 | 51 | 61 | 69 | 4 |
| 3 | 76 | 90 | 102 | 59 | 70 | 79 | 3 |
| 2 | 88 | 105 | 119 | 69 | 83 | 93 | 2 |
| 1 | 102 | 121 | 137 | 80 | 95 | 106 | 1 |
| 1/0 | 121 | 145 | 163 | 94 | 113 | 127 | 1/0 |
| 2/0 | 138 | 166 | 186 | 108 | 129 | 146 | 2/0 |
| 3/0 | 158 | 189 | 214 | 124 | 147 | 167 | 3/0 |
| 4/0 | 187 | 223 | 253 | 147 | 176 | 197 | 4/0 |
| 250 | 205 | 245 | 276 | 160 | 192 | 217 | 250 |
| 300 | 234 | 281 | 317 | 185 | 221 | 250 | 300 |
| 350 | 255 | 305 | 345 | 202 | 242 | 273 | 350 |
| 400 | 274 | 328 | 371 | 218 | 261 | 295 | 400 |
| 500 | 315 | 378 | 427 | 254 | 303 | 342 | 500 |
| 600 | 343 | 413 | 468 | 279 | 335 | 378 | 600 |
| 700 | 376 | 452 | 514 | 310 | 371 | 420 | 700 |
| 750 | 387 | 466 | 529 | 321 | 384 | 435 | 750 |
| 800 | 397 | 479 | 543 | 331 | 397 | 450 | 800 |
| 900 | 415 | 500 | 570 | 350 | 421 | 477 | 900 |
| 1000 | 448 | 542 | 617 | 382 | 460 | 521 | 1000 |
| Correction Factors | |||||||
| Ambient Temp. (°C) | For ambient temperatures other than 30°C (86°F), multiply the ampacities shown above by the appropriate factor shown below. | Ambient Temp. (°F) | |||||
| 21-25 | 1.08 | 1.05 | 1.04 | 1.08 | 1.05 | 1.04 | 70-77 |
| 26-30 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 79-86 |
| 31-35 | 0.91 | 0.94 | 0.96 | 0.91 | 0.94 | 0.96 | 88-95 |
| 36-40 | 0.82 | 0.88 | 0.91 | 0.82 | 0.88 | 0.91 | 97- 104 |
| 41-45 | 0.71 | 0.82 | 0.87 | 0.71 | 0.82 | 0.87 | 106-113 |
| 46-50 | 0.58 | 0.75 | 0.82 | 0.58 | 0.75 | 0.82 | 115-122 |
| 51-55 | 0.41 | 0.67 | 0.76 | 0.41 | 0.67 | 0.76 | 124-131 |
| 56-60 | – | 0.58 | 0.71 | – | 0.58 | 0.71 | 133-140 |
| 61-70 | – | 0.33 | 0.58 | – | 0.33 | 0.58 | 142-158 |
| 71-80 | – | – | 0.41 | – | – | 0.41 | 160-176 |
*Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection for these conductor types shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 AWG amperes for 10 AWG aluminum and copper-clad aluminum.
Table B. 310.3 Ampacities of Multiconductor Cables with Not More Than Three Insulated Conductors, Rated 0 Through 2000 Volts, in Free Air Based on Ambient Air Temperature of 40° C (104° F) (For Types TC, MC, MI, UF, and USE Cables)
| (AWG or kcmil) | Temperature Rating of Conductor. | (AWG or kcmil) | |||||||
| 60°C (140°F) |
75°C (167°F) |
85°C (185°F) |
90°C (194°F) |
60°C (140°F) |
75°C (167°F) |
85°C (185°F) |
90°C (194°F) |
||
| COPPER | ALUMINUM OR COPPER-CLAD ALUMINUM | ||||||||
| 18 | – | – | – | 11* | – | – | – | – | 18 |
| 16 | – | – | – | 16* | – | – | – | – | 16 |
| 14 | 18* | 21* | 24* | 25* | – | – | – | – | 14 |
| 12 | 21* | 28* | 30* | 32* | 18* | 21* | 24* | 25* | 12 |
| 10 | 28* | 36* | 41* | 43* | 21* | 28* | 30* | 32* | 10 |
| 8 | 39 | 50 | 56 | 59 | 30 | 39 | 44 | 46 | 8 |
| 6 | 52 | 68 | 75 | 79 | 41 | 53 | 59 | 61 | 6 |
| 4 | 69 | 89 | 100 | 104 | 54 | 70 | 78 | 81 | 4 |
| 3 | 81 | 104 | 116 | 121 | 63 | 81 | 91 | 95 | 3 |
| 2 | 92 | 118 | 132 | 138 | 72 | 92 | 103 | 108 | 2 |
| 1 | 107 | 138 | 154 | 161 | 84 | 108 | 120 | 126 | 1 |
| 1/0 | 124 | 160 | 178 | 186 | 97 | 125 | 139 | 145 | 1/0 |
| 2/0 | 143 | 184 | 206 | 215 | 111 | 144 | 160 | 168 | 2/0 |
| 3/0 | 165 | 213 | 238 | 249 | 129 | 166 | 185 | 194 | 3/0 |
| 4/0 | 190 | 245 | 274 | 287 | 149 | 192 | 214 | 224 | 4/0 |
| 250 | 212 | 274 | 305 | 320 | 166 | 214 | 239 | 250 | 250 |
| 300 | 237 | 306 | 341 | 357 | 186 | 240 | 268 | 280 | 300 |
| 350 | 261 | 337 | 377 | 394 | 205 | 265 | 296 | 309 | 350 |
| 400 | 281 | 363 | 406 | 425 | 222 | 287 | 317 | 334 | 400 |
| 500 | 321 | 416 | 465 | 487 | 255 | 330 | 368 | 385 | 500 |
| 600 | 354 | 459 | 513 | 538 | 284 | 368 | 410 | 429 | 600 |
| 700 | 387 | 502 | 562 | 589 | 306 | 405 | 462 | 473 | 700 |
| 750 | 404 | 523 | 586 | 615 | 328 | 424 | 473 | 495 | 750 |
| 800 | 415 | 539 | 604 | 633 | 339 | 439 | 490 | 513 | 800 |
| 900 | 438 | 570 | 639 | 670 | 362 | 469 | 514 | 548 | 900 |
| 1000 | 461 | 601 | 674 | 707 | 385 | 499 | 558 | 584 | 1000 |
| Correction Factors | |||||||||
| Ambient Temp. (°C) | For ambient temperatures other than 40°C (104°F), multiply the ampacities shown above by the appropriate factor shown below. | Ambient Temp. (°F) | |||||||
| 21-25 | 1.32 | 1.20 | 1.15 | 1.14 | 1.32 | 1.20 | 1.15 | 1.14 | 70-77 |
| 26-30 | 1.22 | 1.13 | 1.11 | 1.10 | 1.22 | 1.13 | 1.11 | 1.10 | 79-86 |
| 31-35 | 1.12 | 1.07 | 1.05 | 1.05 | 1.12 | 1.07 | 1.05 | 1.05 | 88-95 |
| 36-40 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 97-104 |
| 41-45 | 0.87 | 0.93 | 0.94 | 0.95 | 0.87 | 0.93 | 0.94 | 0.95 | 106-113 |
| 46-50 | 0.71 | 0.85 | 0.88 | 0.89 | 0.71 | 0.85 | 0.88 | 0.89 | 115-122 |
| 51-55 | 0.50 | 0.76 | 0.82 | 0.84 | 0.50 | 0.76 | 0.82 | 0.84 | 124-131 |
| 56-60 | – | 0.65 | 0.75 | 0.77 | – | 0.65 | 0.75 | 0.77 | 133-140 |
| 61-70 | – | 0.38 | 0.58 | 0.63 | – | 0.38 | 0.58 | 0.63 | 142-158 |
| 71-80 | – | – | 0.33 | 0.44 | – | – | 0.33 | 0.44 | 160-176 |
*Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection for these conductor types shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum