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Suggested Ampacities
Assigning a current rating to a wire is really a problem of wire transfer. The watts generated at the conductor must be dissipated through the insulation to the ambient without overheating the conductor or insulation.
While current ratings for power cables have been officially assigned by such groups as the Insulated Cable Engineers Association and the National Electric Code, no such ratings have been officially developed for appliance wires or apparatus cables.
Since appliance and apparatus designs vary widely, any effort to standardize actual current ratings is just about impossible.
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SUGGESTED AMPACITIES (All Types of Single Conductor Insulation)
AWG | 80C | 90C | 105C | 125C | 150C | 200C | 250C* |
---|---|---|---|---|---|---|---|
AMPERES PER CONDUCTOR | |||||||
30 | 2 | 3 | 3 | 3 | 3 | 4 | 4 |
28 | 3 | 4 | 4 | 5 | 5 | 6 | 6 |
26 | 4 | 5 | 5 | 6 | 6 | 7 | 8 |
24 | 6 | 7 | 7 | 8 | 8 | 10 | 11 |
22 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
20 | 10 | 12 | 13 | 14 | 15 | 17 | 19 |
18 | 15 | 16 | 18 | 20 | 22 | 24 | 29 |
16 | 18 | 20 | 24 | 26 | 29 | 32 | 37 |
14 | 20 | 25 | 33 | 40 | 40 | 45 | 39 |
12 | 25 | 30 | 45 | 50 | 50 | 55 | 54 |
10 | 35 | 40 | 58 | 70 | 70 | 75 | 73 |
CORRECTION FACTORS FOR VARIOUS AIR TEMPERATURES | |||||||
---|---|---|---|---|---|---|---|
30 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
40 | 0.88 | 0.90 | 0.92 | 0.95 | 0.96 | 0.97 | 0.98 |
50 | 0.75 | 0.80 | 0.82 | 0.89 | 0.91 | 0.93 | 0.95 |
60 | 0.58 | 0.67 | 0.73 | 0.83 | 0.87 | 0.91 | 0.95 |
70 | 0.35 | 0.52 | 0.61 | 0.76 | 0.82 | 0.87 | 0.93 |
80 | - | 0.30 | 0.46 | 0.69 | 0.76 | 0.84 | 0.90 |
90 | - | - | 0.30 | 0.61 | 0.71 | 0.80 | 0.87 |
100 | - | - | - | 0.51 | 0.65 | 0.77 | 0.85 |
125 | - | - | - | - | 0.50 | 0.66 | 0.72 |
150 | - | - | - | - | - | 0.54 | 0.65 |
200 | - | - | - | - | - | - | 0.49 |
Current ratings for different conductor materials may be calculated by multiplying the appropriate copper conductor ratings by the following factors:
*NICKEL PLATED COPPER: 0.87
NICKEL: 0.43
Suggested Current Carrying Capacity Table (Base Temperature at 40C)
150C |
200C Tinned Copper NPC 2% - 10% |
250C NPC 2% - 10% |
250C "A" Nickel |
250C NPI |
450C NPC - 27% |
450C "A" Nickel |
|
---|---|---|---|---|---|---|---|
24 | 6.6 | 7.2 | 8 | 4 | 3.3 | 9 | 4.3 |
22 | 9 | 9.6 | 10.8 | 5 | 4.4 | 12 | 5.6 |
20 | 13 | 14 | 15 | 7 | 6 | 18 | 8 |
18 | 17 | 18 | 20 | 9.4 | 8 | 23 | 11 |
16 | 22 | 24 | 26 | 12 | 11 | 30 | 14 |
14 | 34 | 36 | 39 | 18 | 16 | 45 | 21 |
12 | 43 | 45 | 54 | 25 | 22 | 56 | 26 |
10 | 55 | 60 | 73 | 34 | 30 | 75 | 35 |
8 | 76 | 83 | 93 | 43 | 39 | 104 | 49 |
6 | 96 | 110 | 117 | 55 | 49 | 138 | 65 |
4 | 120 | 125 | 148 | 69 | 62 | 162 | 76 |
3 | 143 | 152 | 166 | 78 | 69 | 182 | 85 |
2 | 160 | 171 | 191 | 90 | 80 | 210 | 99 |
1 | 186 | 197 | 215 | 101 | 90 | 236 | 110 |
1/0 | 215 | 229 | 244 | 114 | 102 | 268 | 126 |
2/0 | 251 | 260 | 273 | 128 | 114 | 300 | 141 |
3/0 | 288 | 297 | 308 | 144 | 129 | 338 | 159 |
4/0 | 332 | 346 | 361 | 169 | 151 | 397 | 186 |
250 | 365 | 385 | 398 | 187 | 167 | - | - |
300 | 414 | 436 | 452 | 212 | 190 | - | - |
350 | 461 | 486 | 503 | 236 | 211 | - | - |
400 | 495 | 522 | 540 | 254 | 226 | - | - |
500 | 563 | 593 | 613 | 288 | 257 | - | - |
NOTE: For allowable ampacities for fixture wire, please see the National Electrical Code Handbook.
For ambient temperatures other than 40C (104F), multiply the ampacities shown above by the appropriate factor shown below.
Wire Temperature Rating
Ambient Temperature (C) | 200C | 250C | 450C | Ambient Temperature (F) |
---|---|---|---|---|
41-50 | 0.97 | 0.98 | 0.99 | 106-122 |
51-60 | 0.94 | 0.95 | 0.99 | 124-140 |
61-70 | 0.90 | 0.93 | 0.96 | 142-158 |
71-80 | 0.87 | 0.90 | 0.95 | 160-176 |
81-90 | 0.83 | 0.87 | 0.93 | 177-194 |
91-100 | 0.72 | 0.85 | 0.92 | 195-212 |
101-120 | 0.71 | 0.79 | 0.89 | 213-248 |
121-140 | 0.61 | 0.71 | 0.86 | 249-284 |
141-160 | 0.50 | 0.65 | 0.84 | 285-320 |
161-180 | 0.35 | 0.58 | 0.81 | 321-356 |
181-200 | - | 0.49 | 0.78 | 357-392 |
201-225 | - | 0.35 | 0.74 | 393-437 |
226-250 | - | - | 0.69 | 439-482 |
251-275 | - | - | 0.65 | 483-527 |
276-300 | - | - | 0.60 | 528-572 |
301-325 | - | - | 0.55 | 573-617 |
326-350 | - | - | 0.49 | 618-662 |
351-375 | - | - | 0.42 | 663-707 |
376-400 | - | - | 0.34 | 708-752 |
NOTE: The use of this table for establishing ampacity ratings is an inexact procedure. This table should only be used as a starting point when establihsing ratings for any given situations. It is recommended that design engineers desiring accurate ampacity data study the National Electrical Code Handbook - Article 310-13-310-84.
Suggested Ampacities (All Types of Insulations)
COPPER | ALUMINUM | |||||||||||
Not More Than 3 Conductors in Raceway or Cable | Single Conductor in Free Air | Not More Than 3 Conductors in Raceway or Cable | Single Conductor in Free Air | |||||||||
CONDUCTOR TEMPERATURE RATINGS | ||||||||||||
AWG or MCM |
85-90C Temp (185F) |
110C Temp (230F) |
85-90C Temp (185F) |
110C Temp (230F) |
125C Temp (257F) |
200C Temp (392F) |
85-90C Temp (185F) |
110C Temp (185F) |
85-90C Temp (185F) |
110C Temp (230F) |
125C Temp (257F) |
200C Temp (392F) |
AMPERES PER CONDUCTOR (100% LOAD FACTOR) | ||||||||||||
14 | 25 | 30 | 30 | 40 | 40 | 45 | - | - | - | - | - | - |
12 | 30 | 35 | 40 | 50 | 50 | 55 | 25 | 25 | 30 | 40 | 40 | 45 |
10 | 40 | 45 | 55 | 65 | 70 | 75 | 30 | 35 | 45 | 50 | 55 | 60 |
8 | 55 | 60 | 75 | 85 | 90 | 100 | 40 | 45 | 55 | 65 | 70 | 80 |
6 | 70 | 80 | 100 | 120 | 125 | 135 | 55 | 60 | 80 | 95 | 100 | 105 |
4 | 95 | 105 | 135 | 160 | 170 | 180 | 75 | 80 | 105 | 125 | 135 | 140 |
2 | 125 | 135 | 185 | 210 | 225 | 240 | 100 | 105 | 140 | 165 | 175 | 185 |
1 | 145 | 160 | 215 | 245 | 265 | 280 | 110 | 125 | 165 | 190 | 205 | 220 |
0 | 165 | 190 | 250 | 285 | 305 | 325 | 130 | 150 | 190 | 220 | 240 | 255 |
00 | 190 | 215 | 290 | 330 | 355 | 370 | 145 | 170 | 220 | 255 | 275 | 290 |
000 | 215 | 245 | 335 | 385 | 410 | 430 | 170 | 195 | 255 | 300 | 320 | 335 |
0000 | 250 | 275 | 390 | 445 | 475 | 510 | 195 | 215 | 300 | 345 | 390 | 400 |
250 | 275 | 315 | 440 | 495 | 530 | - | 220 | 250 | 330 | 385 | 415 | - |
300 | 310 | 345 | 485 | 555 | 590 | - | 250 | 275 | 375 | 435 | 460 | - |
350 | 340 | 390 | 550 | 610 | 655 | - | 270 | 310 | 415 | 475 | 510 | - |
400 | 365 | 420 | 595 | 665 | 710 | - | 295 | 335 | 450 | 520 | 555 | - |
500 | 415 | 470 | 675 | 765 | 815 | - | 335 | 380 | 515 | 595 | 635 | - |
600 | 460 | 525 | 750 | 855 | 910 | - | 370 | 425 | 585 | 675 | 720 | - |
700 | 500 | 560 | 825 | 940 | 1,005 | - | 405 | 455 | 645 | 475 | 795 | - |
750 | 515 | 580 | 855 | 980 | 1,045 | - | 420 | 470 | 670 | 775 | 825 | - |
800 | 535 | 600 | 885 | 1,020 | 1,085 | - | 430 | 485 | 695 | 805 | 855 | - |
900 | 565 | - | 950 | - | - | - | 465 | - | 750 | - | - | - |
1,000 | 590 | 680 | 1,020 | 1,165 | 1,240 | - | 485 | 560 | 800 | 930 | 990 | - |
CORRECTION FACTORS FOR VARIOUS AMBIENT AIR TEMPERATURES
40C | 0.90 | 0.94 | 0.90 | 0.94 | 0.95 | - | 0.90 | 0.94 | 0.90 | 0.94 | 0.95 | - |
50C | 0.80 | 0.87 | 0.80 | 0.87 | 0.89 | - | 0.80 | 0.87 | 0.80 | 0.87 | 0.89 | - |
60C | 0.67 | 0.79 | 0.67 | 0.79 | 0.83 | 0.91 | 0.67 | 0.79 | 0.67 | 0.79 | 0.83 | 0.91 |
70C | 0.52 | 0.71 | 0.52 | 0.71 | 0.76 | 0.87 | 0.52 | 0.71 | 0.52 | 0.71 | 0.76 | 0.87 |
80C | 0.30 | 0.61 | 0.30 | 0.61 | 0.69 | 0.84 | 0.30 | 0.61 | 0.30 | 0.61 | 0.69 | 0.84 |
90C | - | 0.50 | - | 0.50 | 0.61 | 0.80 | - | 0.50 | - | 0.50 | 0.61 | 0.80 |
100C | - | - | - | - | 0.51 | 0.77 | - | - | - | - | 0.51 | 0.77 |
120C | - | - | - | - | - | 0.69 | - | - | - | - | - | 0.69 |
140C | - | - | - | - | - | - | 0.59 | - | - | - | - | 0.59 |
*Based on an ambient temperature of 30C (86F)