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Ampacity

Badger Wire > Tech Info > Ampacity

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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.

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 .88 .90 .92 .95 .96 .97 .98
50 .75 .80 .82 .89 .91 .93 .95
60 .58 .67 .73 .83 .87 .91 .95
70 .35 .52 .61 .76 .82 .87 .93
80 - .30 .46 .69 .76 .84 .90
90 - - .30 .61 .71 .80 .87
100 - - - .51 .65 .77 .85
125 - - - - .50 .66 .72
150 - - - - - .54 .65
200 - - - - - - .40

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
Tinned Copper		 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
AmbientTemperature(C) 200C 250C 450C AmbientTemperature(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
176-300 - - 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 establishing 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 RATING 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(230F)		 85-90C
Temp(185F)		   110C
Temp(230F)		 125C
Temp(257F)		 200C
Temp(392F)
  AMPERES PER CONDUCTOR
(100% Load Factor)		 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 5   55 65 70 75 30 35 5   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   345 370 400
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 15   475 510 -
400 365 20   595 665 710 - 295 335 50   520 555 -
500 415 70   675 765 815 - 335 380 515   595 635 -
600 460 525   750 855 910 - 370 425 585   675 720 -
700 500 560   825 940 1005 - 405 455 645   745 795 -
750 515 580   855 980 1045 - 420 470 670   775 825 -
800 535 600   885 1020 1085 - 430 485 695   805 855 -
900 565 -   950 - - - 465 - 750   - - -
1000 590 680   1020 1165 1240 - 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)