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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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