Lapp Online Catalog: National Electrical Code Allowable Conductor Ampacity

National Electrical Code
Allowable Conductor Ampacity
Table 310-17

Allowable Ampacities of SINGLE INSULATED CONDUCTORS Rated 0-2000 Volts, In Free Air Based on Ambient Air Temperature of 30°C (86°F)
Size	Temperature Rating of Conductor
AWG (kcmil)	60°C (140°F)	75°C (167°F)	90°C (194°F)
	TYPEs	TYPES	TYPES
	TW†, UF†	FEPW†, RH†, RHW†, THHW†, THW†, THWN†, XHHW†, ZW†	TA, TBS, SA, SIS, FEP†, FEPB†, MI, RHH†, RHW-2, THHN†, THHW†, THW-2, THWN-2, USE-2, XHH, XHHW†, XHHW-2, ZW-2
	COPPER
18	....	....	18
16	....	....	24
14	25 †	30 †	35 †
12	30 †	35 †	40 †
10	40 †	50 †	55 †
8	60	70	80
6	80	95	105
4	105	125	140
3	120	145	165
2	140	170	190
1	165	195	220
1/0	195	230	260
2/0	225	265	300
3/0	260	310	350
4/0	300	360	405
250	340	405	455
300	375	445	505
350	420	505	570
400	455	545	615
500	515	620	700
600	575	690	780
700	630	755	855
750	655	785	885
800	680	815	920
900	730	870	985
1000	780	935	1055
1250	890	1065	1200
1500	980	1175	1325
1750	1070	1280	1445
2000	1155	1385	1560
† Unless otherwise specifically permitted in this Code, the overcurrent protection for conductor types marked with an ebelisk (†) shall not exceed 15 amperes for No.14, 20 amperes for No.12, and 30 amperes for No.10 copper, after any correction factors for ambient temperature and number of conductors have been applied.

Table 310-16

Allowable Ampacities of Insulated Conductors
Rated 0 - 2000 Volts, 60ºC to 90ºC (140º to 194ºF)
Not More Than Three Conductors in Raceway or Cable or Earth
(Directly Buried), Based on Ambient Temperature of 30ºC (86ºF)

Temperature Correction Factors

Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable

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