Online Calculators and Tables to Help You Determine Proper Wire Size


The ampacity chart below shows allowable ampacities of insulated conductors rated up to and including 2000 Volts, 60°C through 90°C (140°F through 194°F), not more than three current-carrying conductors in raceway, cable, or earth (directly buried), based on ambient air temperature of 40°C (104°F).

Wire Size Chart:
Allowable Ampacities of Conductors in Raceway, Cable, or Earth

Source: NFPA 70, National Electrical Code, Table 310.15(B)(18)
SIZE 150°C
(302°F)		 200°C
(392°F)		 250°C
(482°F)		 250°C
(482°F)		 250°C
(482°F)		 450°C
(842°F)		 450°C
(842°F)
AWG
or
kcmil		 TINNED COPPER TINNED COPPER
NPC 2%-10%		 NPC 2%-10% "A" NICKEL NPI NPC 27% "A" NICKEL
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: 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 Free Air (30°C) Maximum Allowable Ampacities for Conductors in Free Air (40°C)

For ambient temperatures other than 40°C, Correction Factors must be taken into consideration.


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