NEC 1999: Chapter 9 Table 4
Dimensions and Percent Area of Conduit and Tubing (See Chapter 9 Table 1 for allowed use of conduit area) | |||||
Electrical Metallic Tubing | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
1⁄2 | 0.622 | 0.304 | 0.161 | 0.094 | 0.122 |
3⁄4 | 0.824 | 0.533 | 0.283 | 0.165 | 0.213 |
1 | 1.049 | 0.864 | 0.458 | 0.268 | 0.346 |
1 1⁄4 | 1.38 | 1.496 | 0.793 | 0.464 | 0.598 |
1 1⁄2 | 1.61 | 2.036 | 1.079 | 0.631 | 0.814 |
2 | 2.067 | 3.356 | 1.778 | 1.04 | 1.342 |
2 1⁄2 | 2.731 | 5.858 | 3.105 | 1.816 | 2.343 |
3 | 3.356 | 8.846 | 4.688 | 2.742 | 3.538 |
3 1⁄2 | 3.834 | 11.545 | 6.119 | 3.579 | 4.618 |
4 | 4.334 | 14.753 | 7.819 | 4.573 | 5.901 |
Electrical Nonmetallic Tubing | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
1⁄2 | 0.56 | 0.246 | 0.131 | 0.076 | 0.099 |
3⁄4 | 0.76 | 0.454 | 0.24 | 0.141 | 0.181 |
1 | 1 | 0.785 | 0.416 | 0.243 | 0.314 |
1 1⁄4 | 1.34 | 1.41 | 0.747 | 0.437 | 0.564 |
1 1⁄2 | 1.57 | 1.936 | 1.026 | 0.6 | 0.774 |
2 | 2.02 | 3.205 | 1.699 | 0.994 | 1.282 |
2 1⁄2 | — | — | — | — | — |
3 | — | — | — | — | — |
3 1⁄2 | — | — | — | — | — |
Flexible Metal Conduit | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
3⁄8 | 0.384 | 0.116 | 0.061 | 0.036 | 0.046 |
1⁄2 | 0.635 | 0.317 | 0.168 | 0.098 | 0.127 |
3⁄4 | 0.824 | 0.533 | 0.283 | 0.165 | 0.213 |
1 | 1.02 | 0.817 | 0.433 | 0.253 | 0.327 |
1 1⁄4 | 1.275 | 1.277 | 0.677 | 0.396 | 0.511 |
1 1⁄2 | 1.538 | 1.858 | 0.985 | 0.576 | 0.743 |
2 | 2.04 | 3.269 | 1.732 | 1.013 | 1.307 |
2 1⁄2 | 2.5 | 4.909 | 2.602 | 1.522 | 1.963 |
3 | 3 | 7.069 | 3.746 | 2.191 | 2.827 |
3 1⁄2 | 3.5 | 9.621 | 5.099 | 2.983 | 3.848 |
4 | 4 | 12.566 | 6.66 | 3.896 | 5.027 |
Intermediate Metal Conduit | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
3⁄8 | — | — | — | — | — |
1⁄2 | 0.66 | 0.342 | 0.181 | 0.106 | 0.137 |
3⁄4 | 0.864 | 0.586 | 0.311 | 0.182 | 0.235 |
1 | 1.105 | 0.959 | 0.508 | 0.297 | 0.384 |
1 1⁄4 | 1.448 | 1.647 | 0.873 | 0.51 | 0.659 |
1 1⁄2 | 1.683 | 2.225 | 1.179 | 0.69 | 0.89 |
2 | 2.15 | 3.63 | 1.924 | 1.125 | 1.452 |
2 1⁄2 | 2.557 | 5.135 | 2.722 | 1.592 | 2.054 |
3 | 3.176 | 7.922 | 4.199 | 2.456 | 3.169 |
3 1⁄2 | 3.671 | 10.584 | 5.61 | 3.281 | 4.234 |
4 | 4.166 | 13.631 | 7.224 | 4.226 | 5.452 |
Liquidtight Flexible Nonmetalic Conduit (LFNC-B) | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
3⁄8 | 0.494 | 0.192 | 0.102 | 0.059 | 0.077 |
1⁄2 | 0.632 | 0.314 | 0.166 | 0.097 | 0.125 |
3⁄4 | 0.83 | 0.541 | 0.287 | 0.168 | 0.216 |
1 | 1.054 | 0.873 | 0.462 | 0.27 | 0.349 |
1 1⁄4 | 1.395 | 1.528 | 0.81 | 0.474 | 0.611 |
1 1⁄2 | 1.588 | 1.981 | 1.05 | 0.614 | 0.792 |
2 | 2.033 | 3.246 | 1.72 | 1.006 | 1.298 |
Liquidtight Flexible Nonmetalic Conduit (LFNC-A) | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
3⁄8 | 0.495 | 0.192 | 0.102 | 0.06 | 0.077 |
1⁄2 | 0.63 | 0.312 | 0.165 | 0.097 | 0.125 |
3⁄4 | 0.825 | 0.535 | 0.283 | 0.166 | 0.214 |
1 | 1.043 | 0.854 | 0.453 | 0.265 | 0.342 |
11⁄4 | 1.383 | 1.502 | 0.796 | 0.466 | 0.601 |
11⁄2 | 1.603 | 2.018 | 1.07 | 0.626 | 0.807 |
2 | 2.063 | 3.343 | 1.772 | 1.036 | 1.337 |
Liquidtight Flexible Metal Conduit (LFMC) | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
3⁄8 | 0.494 | 0.192 | 0.102 | 0.059 | 0.077 |
1⁄2 | 0.632 | 0.314 | 0.166 | 0.097 | 0.125 |
3⁄4 | 0.83 | 0.541 | 0.287 | 0.168 | 0.216 |
1 | 1.054 | 0.873 | 0.462 | 0.27 | 0.349 |
1 1⁄4 | 1.395 | 1.528 | 0.81 | 0.474 | 0.611 |
1 1⁄2 | 1.588 | 1.981 | 1.05 | 0.614 | 0.792 |
2 | 2.033 | 3.246 | 1.72 | 1.006 | 1.298 |
2 1⁄2 | 2.493 | 4.881 | 2.587 | 1.513 | 1.953 |
3 | 3.085 | 7.475 | 3.962 | 2.317 | 2.99 |
3 1⁄2 | 3.52 | 9.731 | 5.158 | 3.017 | 3.893 |
4 | 4.02 | 12.692 | 6.727 | 3.935 | 5.077 |
5 | — | — | — | — | — |
6 | — | — | — | — | — |
Rigid Metal Conduit (RMC) | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
3⁄8 | — | — | — | — | — |
1⁄2 | 0.632 | 0.314 | 0.166 | 0.097 | 0.125 |
3⁄4 | 0.836 | 0.549 | 0.291 | 0.17 | 0.22 |
1 | 1.063 | 0.887 | 0.47 | 0.275 | 0.355 |
1 1⁄4 | 1.394 | 1.526 | 0.809 | 0.473 | 0.61 |
1 1⁄2 | 1.624 | 2.071 | 1.098 | 0.642 | 0.829 |
2 | 2.083 | 3.408 | 1.806 | 1.056 | 1.363 |
2 1⁄2 | 2.489 | 4.866 | 2.579 | 1.508 | 1.946 |
3 | 3.09 | 7.499 | 3.974 | 2.325 | 3 |
3 1⁄2 | 3.57 | 10.01 | 5.305 | 3.103 | 4.004 |
4 | 4.05 | 12.882 | 6.828 | 3.994 | 5.153 |
5 | 5.073 | 20.212 | 10.713 | 6.266 | 8.085 |
6 | 6.093 | 29.158 | 15.454 | 9.039 | 11.663 |
Rigid PVC Conduit (PVC), Schedule 80 | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
3⁄8 | — | — | — | — | — |
1⁄2 | 0.526 | 0.217 | 0.115 | 0.067 | 0.087 |
3⁄4 | 0.722 | 0.409 | 0.217 | 0.127 | 0.164 |
1 | 0.936 | 0.688 | 0.365 | 0.213 | 0.275 |
1 1⁄4 | 1.255 | 1.237 | 0.656 | 0.383 | 0.495 |
1 1⁄2 | 1.476 | 1.711 | 0.907 | 0.53 | 0.684 |
2 | 1.913 | 2.874 | 1.523 | 0.891 | 1.15 |
2 1⁄2 | 2.29 | 4.119 | 2.183 | 1.277 | 1.647 |
3 | 2.864 | 6.442 | 3.414 | 1.997 | 2.577 |
3 1⁄2 | 3.326 | 8.688 | 4.605 | 2.693 | 3.475 |
4 | 3.786 | 11.258 | 5.967 | 3.49 | 4.503 |
5 | 4.768 | 17.855 | 9.463 | 5.535 | 7.142 |
6 | 5.709 | 25.598 | 13.567 | 7.935 | 10.239 |
Rigid PVC Conduit, Schedule 40, and HDPE Conduit | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
3⁄8 | — | — | — | — | — |
1⁄2 | 0.602 | 0.285 | 0.151 | 0.088 | 0.114 |
3⁄4 | 0.804 | 0.508 | 0.269 | 0.157 | 0.203 |
1 | 1.029 | 0.832 | 0.441 | 0.258 | 0.333 |
1 1⁄4 | 1.36 | 1.453 | 0.77 | 0.45 | 0.581 |
1 1⁄2 | 1.59 | 1.986 | 1.052 | 0.616 | 0.794 |
2 | 2.047 | 3.291 | 1.744 | 1.02 | 1.316 |
2 1⁄2 | 2.445 | 4.695 | 2.488 | 1.455 | 1.878 |
3 | 3.042 | 7.268 | 3.852 | 2.253 | 2.907 |
3 1⁄2 | 3.521 | 9.737 | 5.161 | 3.018 | 3.895 |
4 | 3.998 | 12.554 | 6.654 | 3.892 | 5.022 |
5 | 5.016 | 19.761 | 10.473 | 6.126 | 7.904 |
6 | 6.031 | 28.567 | 15.141 | 8.856 | 11.427 |
Type A, Rigid PVC Conduit | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
1⁄2 | 0.7 | 0.385 | 0.204 | 0.119 | 0.154 |
3⁄4 | 0.91 | 0.65 | 0.345 | 0.202 | 0.26 |
1 | 1.175 | 1.084 | 0.575 | 0.336 | 0.434 |
1 1⁄4 | 1.5 | 1.767 | 0.937 | 0.548 | 0.707 |
1 1⁄2 | 1.72 | 2.324 | 1.231 | 0.72 | 0.929 |
2 | 2.155 | 3.647 | 1.933 | 1.131 | 1.459 |
2 1⁄2 | 2.635 | 5.453 | 2.89 | 1.69 | 2.181 |
3 | 3.23 | 8.194 | 4.343 | 2.54 | 3.278 |
3 1⁄2 | 3.69 | 10.694 | 5.668 | 3.315 | 4.278 |
4 | 4.18 | 13.723 | 7.273 | 4.254 | 5.489 |
5 | — | — | — | — | — |
6 | — | — | — | — | — |
Type EB, Rigid PVC Conduit | |||||
Trade Size | Internal Diameter | Total
Area 100% |
1 Wire 53% |
2 Wires 31% |
Over 2
Wires 40% |
in. | in.² | in.² | in.² | in.² | |
1⁄2 | — | — | — | — | — |
3⁄4 | — | — | — | — | — |
1 | — | — | — | — | — |
1 1⁄4 | — | — | — | — | — |
1 1⁄2 | — | — | — | — | — |
2 | 2.221 | 3.874 | 2.053 | 1.201 | 1.55 |
2 1⁄2 | — | — | — | — | — |
3 | 3.33 | 8.709 | 4.616 | 2.7 | 3.484 |
3 1⁄2 | 3.804 | 11.365 | 6.023 | 3.523 | 4.546 |
4 | 4.289 | 14.448 | 7.657 | 4.479 | 5.779 |
5 | 5.316 | 22.195 | 11.763 | 6.881 | 8.878 |
6 | 6.336 | 31.53 | 16.711 | 9.774 | 12.612 |
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