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Allowable ampacities of conductors

Allowable ampacities of insulated conductors Rated 0 - 200 volts,
60 °C through 90 °C (140 °F through 194 °F). Not more than three current-carring
conductors in raceway, cable, or earth (directly burried), based on ambient
air temperature of 30 °C (86 °F)
SIZE 60°C
(140°F)
75°C
(167°F)
90°C
(194°F)
60°C
(140°F)
75°C
(167°F)
90°C
(194°F)
SIZE
AWG 
or
kcmil
TYPES
TW,
UP
TYPES
RHW,
 THHW,
THW,
THWN,
XHHW,
USE,
ZW
TYPES
TBS,
SA,
SIS,
FEP,
FEPB,
RHH,MI,
RHW-2,
THHN,
THHW,
THW-2,
THWN-2,
USE-2, XHH,
XHHW,
XHHW-2,
ZW-2
TYPES
TW,
UF
TYPES
RHW,
THHW,
THW,
THWN,
XHHW,
USE
TYPES
TBS,
SA,
SIS,
THHN,
THHW,
THW-2,
THWN-2,
RHH,
RHW-2,
USE-2,
XHH,
XHHW,
XHHW-2,
ZW-2
AWG
or
kcmil
COOPER ALUMINUM OR COPPER-CLAD ALUMINUM
14* 20 20 25 - - - 14
12* 25 25 30 20 20 25 12*
10* 30 35 40 25 30 35 10*
8    40 50 55 30 40 45 8
6    55 65 75 40 50 60 6
4    70 85 95 55 65 75 4
3    85 100 110 65 75 85 3
2    95 115 130 75 90 100 2
1    110 130 150 85 100 115 1
1/0 125 150 170 100 120 135 1/0
2/0 145 175 195 115 135 150 2/0
3/0 165 200 225 130 155 175 3/0
4/0 195 230 260 150 180 205 4/0
250    215 255 290 170 205 230 250
300    240 285 320 190 230 255 300
350    260 310 350 210 250 280 350
400    280 335 380 225 270 305 400
500    320 380 430 260 310 350 500
600    355 420 475 285 340 385 600
700    385 460 520 310 375 420 700
750    400 475 535 320 385 435 750
800    410 490 555 330 395 450 800
900    435 520 585 355 425 480 900
1000    455 545 615 375 445 500 1000
1250    495 590 665 405 485 545 1250
1500    520 625 705 435 520 585 1500
1750    545 650 735 455 545 615 1750
2000    560 665 750 470 560 630 2000
Ambient
Temp °C
TEMPERATRUE CORRECTION FACTORS
For ambient temperatures other than 30 °C, multiply the allowable
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 78-86
31-35 0.91 0.94 0.96 0.91 0.94 0.96 87-95
36-40 0.82 0.88 0.91 0.82 0.88 0.91 96-104
41-45 0.71 0.82 0.87 0.71 0.82 0.87 105-113
46-50 0.58 0.75 0.82 0.58 0.75 0.82 114-122
51-55 0.41 0.67 0.76 0.41 0.67 0.76 123-131
56-60 - 0.58 0.71 - 0.58 0.71 132-140
61-70 - 0.33 0.58 - 0.33 0.58 141-158
71-80 - - 0.41 - - 0.41 159-176

* Unless specificaly permitted in 240.4 (E) or 240.4 (G), the overcurrent protection
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 after correction factors for ambient temperature and number
of conductors have been applied.

  © Ugly's™ Electrical References revised 2008 Edition