Online Calculators and Tables to Help You Determine Proper Wire Size


The ampacity chart below shows the allowable ampacities of single-insulated electrical wire rated up to and including 2000 Volts in free air, based on Ambient Air Temperature of 30°C (86°F).

Wire Size Chart:
Allowable Ampacities of Conductors in Free Air

Source: NFPA 70, National Electrical Code, Table 310.15(B)(17)
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,
UF		 TYPES
RHW,
THW,
THWN		 TYPES
TBS,
SA,
SIS		 TYPES
TW,
UF		 TYPES
RHW,
THW,
THWN		 TYPES
TBS,
SA,
SIS		 AWG
or
kcmil
COPPER ALUMINUM
14 25 30 35 – – – 14
12 30 35 40 25 30 35 12
10 40 50 55 35 40 40 10
8 60 70 80 45 55 60 8
6 80 95 105 60 75 80 6
4 105 125 140 80 100 110 4
3 120 145 165 95 115 130 3
2 140 170 190 110 135 150 2
1 165 195 220 130 155 175 1
1/0 195 230 260 150 180 205 1/0
2/0 225 265 300 175 210 235 2/0
3/0 260 310 350 200 240 275 3/0
4/0 300 360 405 235 280 315 4/0
250 340 405 455 265 315 355 250
300 375 445 505 290 350 395 300
350 420 505 570 330 395 445 350
400 455 545 615 355 425 480 400
500 515 620 700 405 485 545 500
600 575 690 780 455 540 615 600
700 630 755 855 500 595 675 700
750 655 785 885 515 620 700 750
800 680 815 920 535 645 725 800
900 730 870 985 580 700 785 900
1000 780 935 1055 625 750 845 1000
1250 890 1065 1200 710 855 960 1250
1500 980 1175 1325 795 950 1075 1500
1750 1070 1280 1445 875 1050 1185 1750
2000 1155 1385 1560 960 1150 1335 2000

Note: View additional wire size charts from the list below.

Maximum Allowable Ampacities for Conductors in Raceway, Cable or Earth (30°C) Maximum Allowable Ampacities for Conductors in Raceway, Cable or Earth (40°C) Maximum Allowable Ampacities for Conductors in Free Air (40°C)

For ambient temperatures other than 30°C, Correction Factors must be taken into consideration.


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