NEC Table 310.16 — Conductor Ampacity

Not more than three current-carrying conductors in a raceway, cable or directly buried, 30°C (86°F) ambient. The everyday table — formerly numbered 310.15(B)(16).

Most-used values (copper, 75°C): 14 AWG 20 A · 12 AWG 25 A · 10 AWG 35 A · 8 AWG 50 A · 6 AWG 65 A · 4 AWG 85 A · 3 AWG 100 A · 1 AWG 130 A · 2/0 175 A · 3/0 200 A · 4/0 230 A · 500 kcmil 380 A.

Ampacity in amps — insulated conductors, 0–2000 V, not more than three current-carrying conductors, 30°C ambient
	Copper			Aluminum or copper-clad aluminum
Size	60°C	75°C	90°C	60°C	75°C	90°C
18 AWG	—	—	14	—	—	—
16 AWG	—	—	18	—	—	—
14 AWG	15	20	25	—	—	—
12 AWG	20	25	30	15	20	25
10 AWG	30	35	40	25	30	35
8 AWG	40	50	55	35	40	45
6 AWG	55	65	75	40	50	55
4 AWG	70	85	95	55	65	75
3 AWG	85	100	115	65	75	85
2 AWG	95	115	130	75	90	100
1 AWG	110	130	145	85	100	115
1/0 AWG	125	150	170	100	120	135
2/0 AWG	145	175	195	115	135	150
3/0 AWG	165	200	225	130	155	175
4/0 AWG	195	230	260	150	180	205
250 kcmil	215	255	290	170	205	230
300 kcmil	240	285	320	195	230	260
350 kcmil	260	310	350	210	250	280
400 kcmil	280	335	380	225	270	305
500 kcmil	320	380	430	260	310	350
600 kcmil	350	420	475	285	340	385
700 kcmil	385	460	520	315	375	425
750 kcmil	400	475	535	320	385	435
800 kcmil	410	490	555	330	395	445
900 kcmil	435	520	585	355	425	480
1000 kcmil	455	545	615	375	445	500
1250 kcmil	495	590	665	405	485	545
1500 kcmil	525	625	705	435	520	585
1750 kcmil	545	650	735	455	545	615
2000 kcmil	555	665	750	470	560	630

Small-conductor limit: overcurrent protection is capped at 15 A for 14 AWG, 20 A for 12 AWG and 30 A for 10 AWG copper; 15 A for 12 AWG and 25 A for 10 AWG aluminum.

Which insulation types use which column
Column	Conductor types
60°C (140°F)	TW, UF
75°C (167°F)	RHW, THHW, THW, THWN, XHHW, USE, ZW
90°C (194°F)	TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, ZW-2

Ampacity & derating calculator

Installation

Conductor

Wire size

Insulation rating

Ambient temperature

Current-carrying conductors

Termination rating

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Ambient above 30°C or more than three loaded conductors? See the derating tables.

Frequently asked questions

Which ampacity column should I use — 60, 75 or 90°C?

Use the column for the lowest-rated part of the circuit. Breakers, panels and most equipment are rated 75°C, so 75°C is the normal answer. Equipment rated 100 A or less, or marked for 14–1 AWG, is treated as 60°C unless it is marked 75°C. NM-B cable is limited to the 60°C column by 334.80. The 90°C column is used only as the starting point for derating.

What is the ampacity of 12 gauge wire?

12 AWG copper is 20 A at 60°C, 25 A at 75°C and 30 A at 90°C, but 240.4(D) limits its overcurrent protection to 20 A in almost all cases. 12 AWG aluminum is 15, 20 and 25 A with a 15 A limit.

Is Table 310.16 the same as 310.15(B)(16)?

Yes. It was Table 310.16 through the 2008 NEC, became 310.15(B)(16) in 2011–2017, and returned to 310.16 in the 2020 edition. The ampacity values are identical.

What conditions does Table 310.16 assume?

Conductors rated up to 2000 V, no more than three current-carrying conductors in a raceway, cable or direct-buried, and an ambient temperature of 30°C (86°F). Anything else needs the correction and adjustment factors.

NECTables.com is an independent reference and is not affiliated with, endorsed by, or a substitute for the National Fire Protection Association (NFPA). NEC® and National Electrical Code® are registered trademarks of the NFPA. Values shown are commonly published engineering data and independent calculations based on the methods of NFPA 70; they are not a reproduction of the Code. Always confirm against the edition adopted in your jurisdiction, including local amendments, and consult a licensed electrician or engineer before doing electrical work.