Copper Wire Ampacity Table – Free Air, 30 °C

Ampacities of Copper Wire in Free Air at 30 °C

This reference table lists the current ratings for common copper wire sizes with various insulation types, measured in free air at 30 °C. The ratings are provided for 60 °C, 75 °C, and 90 °C temperature points. Values marked with an asterisk (*) are estimated; wire sizes that small are rarely available with these insulation types.

RUW, T Insulation

Size (AWG)	60 °C	90 °C
20	*9	*12.5
18	*13	18
16	*18	24

THW, THWN Insulation (Common for 14 AWG and Smaller)

Size (AWG)	60 °C	75 °C	90 °C
14	25	30	35
12	30	35	40
10	40	50	55
8	60	70	80
6	80	95	105
4	105	125	140
2	140	170	190
1	165	195	220
1/10	195	230	260
2/0	225	265	300
3/0	260	310	350
4/0	300	360	405

* = estimated values; normally, wire gauges this small are not manufactured with these insulation types.

Related Worksheets:

Overcurrent Protection Worksheet
Wire Types and Sizes Worksheet

Comprehensive Copper Wire Gauge Table – Sizes, Diameters, Areas & Weights Specific Resistance Coefficients at 20°C – Comprehensive Material Reference

Industrial Technology

Manufacturing process

3D printing

Automation Control System

Industrial Technology

Copper Wire Ampacity Table – Free Air, 30 °C

RUW, T Insulation

THW, THWN Insulation (Common for 14 AWG and Smaller)

Copper Wire Ampacity Table – Free Air, 30 °C

THW, THWN Insulation (Common for 14 AWG and Smaller)