Connectivity Guide

Table 310.15(B)(17) for copper conductors

Allowable ampacities of single insulated conductors rated 0–2000V, in free air. 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

— —

— —

18 24

25* 30* 40*

30* 35* 50*

35* 40* 55* 105 140 165 190 220 260 300 350 405 455 505 570 615 700 80

60 80

70 95

105 120 140 165 195 225 260 300 340 375 420 455 515

125 145 170 195 230 265 310 360 405 445 505 545 620

* 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.

Adjustment factors for more than three current-carrying conductors

Where the number of current-carrying conductors exceeds three, the allowable ampacity should be reduced as shown. If adjustment is needed for ambient temperature, do that first using the table to the left.

Percent Adjustment as adjusted for ambient temperature, if necessary

Number of Current- Carrying Conductors*

4–6 7–9

80% 70% 50% 45% 40% 35%

10–20 21–30 31–40

more than 40

* Does not include ground

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