ALUMINUM BUS PHYSICAL ELECTRICAL CHARACTERISTICS - STANDARD PIPE SIZES Standard Iron Pipe Size, Inches Diameter, Inches Wall Thickness, Inches Area, SQ. IN. Weight. LB. Per FT. Resistance Microhms Per FT. Moment of Inertia. IN.4 Section Modules IN.³ Radius of Gyration, Inches Current Capacity, Amperes, 60-Cycle A.C. Outside Inside ¼ 0.540 0.364 0.088 0.125 0.147 106.82 0.0033 0.0123 0.1628 200  3/8 0.675 0.493 0.091 0.167 0.196 80.42 0.0073 0.0216 0.2090 250 ½ 0.840 0.622 0.109 0.250 0.294 53.44 0.0171 0.0407 0.2613 340 ¾ 1.050 0.824 0.113 0.333 0.390 40.10 0.0370 0.0705 0.3337 435 1 1.315 1.049 0.133 0.494 0.580 26.97 0.0873 0.1328 0.4205 590 1¼ 1.660 1.380 0.140 0.668 0.785 19.99 0.1947 0.2346 0.5397 740 1½ 1.900 1.610 0.145  0.800 0.939  16.70 0.3099 0.3262 0.6226 840 2 2.375 2.067 0.154 1.075 1.262 12.42     0.6657 0.5606 0.7871 1100 2½ 2.875 2.469 0.203 1.704  2.002 7.82 1.5300 1.0649 0.9474 1490 3 3.500 3.068 0.216 2.228 2.617 5.98 3.0177 1.7244 1.1640 1765 3½ 4.000 3.548 0.226 2.680 3.147 4.78 4.7877 2.3938 1.3370 2030 4 4.500 4.026 0.237 3.174 3.729 4.21 7.2325 3.2144 1.5100 2300 4½ 5.000 4.506 0.247 3.688 4.333 3.62 10.4433 4.1773 1.6830 2730 5 5.563 5.047 0.258 4.300 5.051 3.11 15.1600 5.4510 1.8780 3100  6 6.625 6.065 0.280 5.581 6.556 2.39 28.1400 8.4960 2.2450 3860

NOTES:

1. For outdoor locations with a cross wind of 2 feet per second, the ratings for tubes 1 inch and above may be increased 14 to 22 per cent, depending upon conductor diameter.  The increase for smaller conductors is somewhat higher.
2. Current ratings are for 30° C. rise over 40° C. ambient temperature in still but unconfined air.