CH 3

Conductor Ampacities

NEC 2020 • 2023 COMPLIANTQUICK

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Select NEC Edition:NEC 2020 NEC 2023 NEC 2026

High-speed reference for common Copper and Aluminum wire sizes (60°C to 90°C).

Size (AWG/kcmil)	Copper 60°C (TW)	Copper 75°C (THWN-2)	Copper 90°C (THHN)	Alum 60°C	Alum 75°C	Alum 90°C
16	10	10	10	-	-	-
14	15	20	25	-	-	-
12	20	25	30	15	20	25
10	30	35	40	25	30	35
8	40	50	55	30	40	45
6	55	65	75	40	50	60
4	70	85	95	55	65	75
3	85	100	110	65	75	85
2	95	115	130	75	90	100
1	110	130	150	85	100	115
1/0	125	150	170	100	120	135
2/0	145	175	195	115	135	150
3/0	165	200	225	130	155	175
4/0	195	230	260	150	180	205

Pro Calculation Tool

Use the Wire Ampacity Calculator

Related NEC Tables

Table 310.15(B)(1): Temperature Correction Table 310.15(C)(1): Conductor Adjustment View Full Table 310.16

Professional Usage Disclaimer

This data is provided for informational purposes only. Always verify with the latest edition of the National Electrical Code (NFPA 70) and consult with a licensed electrical professional or AHJ (Authority Having Jurisdiction) before performing any electrical work. Zing² is a reference tool, not a substitute for qualified engineering.

Professional Field Notes & Gotchas

▸The 75°C Terminal Rule: Per NEC 110.14(C), even if you use 90°C wire (THHN/XHHW-2), you must size based on the 75°C column because most equipment terminals are not rated for 90°C.
▸Derating Base: You ARE allowed to use the 90°C column as the starting point for ambient temperature or bundling adjustments, as long as the final result doesn't exceed the 75°C rating.
▸Rooftop Heat: For wires on roofs, add the 'standard' ambient temperature correction PLUS any specific sun-loading factors required by local AHJs.
▸Aluminum vs. Copper: Aluminum wire requires significantly larger gauge (roughly 2 sizes up) to match the ampacity of Copper due to its lower conductivity.

NEC 2023 vs 2026: What changed?

NEC 2023 vs 2026: The 2026 code has maintained the primary ampacity values but simplified the notes regarding 'Adjustment' vs 'Correction' factors to ensure more intuitive math for complex multi-raceway installations.

Technical FAQs

What is the ampacity of 6 AWG THHN?

At 75°C (most terminal ratings), 6 AWG Copper is rated for 65 Amps. At 90°C (for derating base only), it is rated for 75 Amps.

Can I use 2/0 Aluminum for a 200A service?

In most residential single-phase cases using the 83% rule (Table 310.12), yes. However, for a standard industrial feeder per Table 310.16, 2/0 Al is only rated for 135 Amps at 75°C.

Why is 14 AWG limited to 15 Amps?

While the table shows higher values, NEC 240.4(D) 'Small Conductor Rule' generally limits 14 AWG to 15A, 12 AWG to 20A, and 10 AWG to 30A overcurrent protection.

Size (AWG/kcmil)	Copper 60°C (TW)	Copper 75°C (THWN-2)	Copper 90°C (THHN)	Alum 60°C	Alum 75°C	Alum 90°C
16	10	10	10	-	-	-
14	15	20	25	-	-	-
12	20	25	30	15	20	25
10	30	35	40	25	30	35
8	40	50	55	30	40	45
6	55	65	75	40	50	60
4	70	85	95	55	65	75
3	85	100	110	65	75	85
2	95	115	130	75	90	100
1	110	130	150	85	100	115
1/0	125	150	170	100	120	135
2/0	145	175	195	115	135	150
3/0	165	200	225	130	155	175
4/0	195	230	260	150	180	205

Size (AWG/kcmil)	Copper 60°C (TW)	Copper 75°C (THWN-2)	Copper 90°C (THHN)	Alum 60°C	Alum 75°C	Alum 90°C
16	10	10	10	-	-	-
14	15	20	25	-	-	-
12	20	25	30	15	20	25
10	30	35	40	25	30	35
8	40	50	55	30	40	45
6	55	65	75	40	50	60
4	70	85	95	55	65	75
3	85	100	110	65	75	85
2	95	115	130	75	90	100
1	110	130	150	85	100	115
1/0	125	150	170	100	120	135
2/0	145	175	195	115	135	150
3/0	165	200	225	130	155	175
4/0	195	230	260	150	180	205

Size (AWG/kcmil)	Copper 60°C (TW)	Copper 75°C (THWN-2)	Copper 90°C (THHN)	Alum 60°C	Alum 75°C	Alum 90°C
16	10	10	10	-	-	-
14	15	20	25	-	-	-
12	20	25	30	15	20	25
10	30	35	40	25	30	35
8	40	50	55	30	40	45
6	55	65	75	40	50	60
4	70	85	95	55	65	75
3	85	100	110	65	75	85
2	95	115	130	75	90	100
1	110	130	150	85	100	115
1/0	125	150	170	100	120	135
2/0	145	175	195	115	135	150
3/0	165	200	225	130	155	175
4/0	195	230	260	150	180	205