Connectivity Guide

National Electrical Code: Allowable Conductor Ampacity

Table 310.15(B)(16) for copper conductors

Allowable ampacities of insulated conductors rated 0–2000V, 60° to 90°C (140° to 194°F) not more than three conductors in raceway or cable or earth (directly buried). Based on ambient air temperature of 30°C (86°F).

Temperature Rating

60°C (140°F)

75°C (167°F)

90°C (194°F)

Types

Types

Types

Copper Conductor Size

TW*

UF*

FEPW* RHW* THW* XHHW* ZW*

RH* THHW* THWN* USE*

TA SIS MI THHN* THWN-2 XHHW*

TBS FEP* RHH* THHW* USE-2 XHHW-2

SA FEPB* RHW-2 THW-2 XHH ZW-2

18 AWG 16 AWG 14 AWG 12 AWG 10 AWG 8 AWG 6 AWG 4 AWG 3 AWG 2 AWG 1 AWG 1/0 AWG 2/0 AWG 3/0 AWG 4/0 AWG 250 KCMIL 300 KCMIL 350 KCMIL 400 KCMIL 500 KCMIL

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14 18

20* 25*

20* 25* 35*

25* 30* 40*

30 40 55 70 85 95

50 65 85

55 75 95

100 115 130 150 175 200 230 255 285 310 335 380

110 130 150 170 195 225 260 290 320 350 380 430

110 125 145 165 195 215 240 260 280 320

* Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection for conductor types marked with an asterisk shall not exceed 15A for No. 14 copper, 20A for No. 12 copper, and 30A for No. 10 copper, after any correction factors for ambient temperature and number of conductors have been applied.

Temperature correction factors

For ambient temperatures other than 30°C (86°F), multiply the allowable ampacity from the above tables by the appropriate factor below:

Ambient Temperature

60°C 140°F 1.00 0.82 0.58

75°C 167°F 1.00 0.88 0.75 0.58 0.33

90°C 194°F 1.00 0.91 0.82 0.58 0.58

°C

°F

30°C 40°C 50°C 60°C 70°C 80°C

86°F

104°F 122°F 140°F 158°F 176°F

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