NATIONAL ELECTRICAL CODE

3½ 3.548 9.90 3.07 3.96 5.25 5.44 2.97 3.96 3.76 3.47 4 4.026 12.72 3.94 5.09 6.74 7.00 3.82 5.09 4.83 4.45 5 5.047 20.00 6.20 8.00 10.60 11.00 6.00 8.00 7.60 7.00 6 6.065 28.89 8.96 11.56 15.31 15.89 8.67 11.56 10.98 10.11 Table 5. Dimensions of Rubber-Covered and Thermoplastic-Covered Conductors Types**** Types FEP, FEPB, FEPW, RFH-2, RH, Types Types TFE, PF, PFA, Types Types RHH,***, RHW-2, TF, THW+, TFN, THHN, PFAH, PGF, PTF, XHHW, ZWH, KF-1, KF-2, RHW,* SF-2 TW, THHW THWN Z, ZF, ZFF XHHW-2 KFF-1, KFF-2 Size Approx. Approx. Approx. Approx. Approx. Approx. Approx. Approx. Approx. Approx. Approx. Approx. AWG Diam. Area Diam. Area Diam. Area Diam. Area Diam. Area Diam. Area kcmil Inches Sq. In. Inches Sq. In. Inches Sq. In. Inches Sq. In. Inches Sq. In. Inches Sq. In. Col.1 Col.2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 Col. 12 Col. 13 18 .146 .0167 .106 .0088 .089 .0062 .081 .0052 .065 .0033 16 .158 .0196 .118 .0109 .100 .0079 .092 .0066 .070 .0038 14 30 mils .171 .0230 .131 .0135 .105 .0087 .105 .105 .0087 .0087 .083 .0054 14 45 mils .204* .0327* 14 .162+ .0206+ 129 .0131 12 30 mils .188 .0278 .148 .0172 .122 .0117 121 .121 .0115 .0115 .102 .0082 12 45 mils .221* .0384* 12 .179+ .0252+ 146 .0167 10 .242 .0460 .168 .0222 .153 .0184 .142 .142 .0158 .0158 .124 .0121 CHAPTER 9 AND EXAMPLES 10 .199+ .0311+ 166 .0216 8 .328 .0845 .245 .0471 .218 .0373 .206 .186 .0333 .0272 8 .276+ .0598+ 241 .0456 6 .397 .1238 .323 .0819 .257 .0519 .244 .302 .0468 .0716 .282 .0625 4 .452 .1605 .372 .1087 .328 .0845 .292 .350 .0670 .0962 .328 .0845 3 .481 1817 .401 .1263 .356 .0995 .320 .378 .0804 .1122 .356 .0995 2 .513 .2067 .433 .1473 .388 .1182 .352 .410 .0973 .1320 .388 .1182 1 .588 .2715 .508 .2027 .450 .1590 .420 .1385 .450 .1590 1/0 .629 .3107 .549 .2367 .491 .1893 .462 .1676 .491 .1893 2/0 .675 .3578 .595 .2781 .537 .2265 .498 .1948 .537 .2265 3/0 .727 .4151 .647 .3288 .588 .2715 .560 .2463 .588 .2715 70-825 4/0 .785 .4840 .705 .3904 .646 .3278 .618 .3000 .646 .3278 Table 5. (Continued) Types**** Types FEP, FEPB, FEPW, 70-826 RFH-2, RH, Types Types TFE, PF, PFA, Types RHH, RHW-2, TF, THW+, TFN, PFAH, PGF, PTF, XHHW, ZWH, RHW,* SF-2 TW, THHW THHN, THWN Z, ZF, ZFF XHHW-2 Size Approx. Approx. Approx. Approx. Approx. Approx. Approx. Approx. Approx. Approx. AWG Diam. Area Diam. Area Diam. Area Diam. Area Diam. Area kcmil Inches Sq. In. Inches Sq. In. Inches Sq. In. Inches Sq. In. Inches Sq. In. Col.1 Col.2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 250 .868 .5917 .788 .4877 .716 .4026 .716 .4026 300 .933 .6837 .843 .5581 .771 .4669 .771 .4669 350 .985 .7620 .895 .6291 .822 .5307 .822 .5307 400 1.032 .8365 .942 .6969 .869 .5931 .869 .5931 500 1.119 .9834 1.029 .8316 .955 .7163 .955 .7163 600 1.233 1.1940 1.143 1.0261 1.058 .8791 1.073 .9043 700 1.304 1.3355 1.214 1.1575 1.129 1.0011 1.145 1.0297 750 1.339 1.4082 1.249 1.2252 1.163 1.0623 1.180 1.0936 800 1.372 1.4784 1.282 1.2908 1.196 1.1234 1.210 1.1499 NATIONAL ELECTRICAL CODE 900 1.435 1.6173 1.345 1.4208 1.259 1.2449 1.270 1.2668 1000 1.494 1.7530 1.404 1.5482 1.317 1.3623 1.330 1.3893 1250 1.676 2.2062 1.577 1.9532 1.500 1.7671 1500 1.801 2.5475 1.702 2.2751 1.620 2.0612 1750 1.916 2.8832 1.817 2.5930 1.740 2.3779 2000 2.021 3.2079 1.922 2.9013 1.840 2.6590 * The dimensions of Types RHH and RHW with outer covering. + Dimensions of THW in sizes No. 14 through No. 8. Nos. 6 THW and larger are the same dimension as TW. Dimensions of RHH and RHW without outer coverings are the same as THW No. 18 through No. 10, solid; Nos. 8 and larger, stranded. **** In Columns 8 and 9, the values shown for size Nos. 1 through 4/0 are for TFE and Z only. The right-hand values in Columns 8 and 9 are for FEPB, Z, ZF, and ZFF only. ++ No. 14 through No. 2. Table 5A. Compact Aluminum Building Wire Nominal Dimensions* and Areas Bare Conductor Types THW and THHW Type THHN Type XHHW Size Number Approx. Approx. Approx. Approx. Approx. Approx. Size AWG or of Diam. Diam. Area Diam. Area Diam. Area AWG or kcmil Strands Inches Inches Sq. In. Inches Sq. In. Inches Sq. Inches kcmil 8 7 .134 .255 .0510 - - .224 .0394 8 6 7 .169 .290 .0660 .240 .0452 .260 .0530 6 4 7 .213 .335 .0881 .305 .0730 .305 .0730 4 2 7 .268 .390 .1194 .360 .1017 .360 .1017 2 1 19 .299 .465 .1698 .415 .1352 .415 .1352 1 1/0 19 .336 .500 .1963 .450 .1590 .450 .1590 1/0 2/0 19 .376 .545 .2332 .495 .1924 .490 .1885 2/0 3/0 19 .423 .590 .2733 .540 .2290 .540 .2290 3/0 4/0 19 .475 .645 .3267 .595 .2780 .590 .2733 4/0 250 37 .520 .725 .4128 .670 .3525 .660 .3421 250 300 37 .570 .775 .4717 .720 .4071 .715 .4015 300 350 37 .616 .820 .5281 .770 .4656 .760 .4536 350 400 37 .659 .865 .5876 .815 .5216 .800 .5026 400 CHAPTER 9 - TABLES AND EXAMPLES 500 37 .736 .940 .6939 .885 .6151 .880 .6082 500 600 61 .813 1.050 .8659 .985 .7620 .980 .7542 600 700 61 .877 1.110 .9676 1.050 .8659 1.050 .8659 700 750 61 .908 1.150 1.0386 1.075 .9076 1.090 .9331 750 1000 61 1.060 1.285 1.2968 1.255 1.2370 1.230 1.1882 1000 * Dimensions are from industry sources. 70-827 Table 5B. Maximum Number of Compact Conductors in Trade Sizes of Conduit or Tubing Insulation Type 70-828 Conductor T T T X T T T X T T T X T T T X T T TXTTTXTTTXTTTX Conductor Size HHHH HHHH HHHH Size AWG or WHHH WHHHWHHH WHHH WHHH WHHH WHHHWHHH AWG or kcmil WNW WNW WNW WNW WNW WNW WNW WNW kcmil I Conduit or Tubing Trade Size 1 in. 1½ in. 1½ in. 2 in. 2½ in. 3 in. 3½ in. 4 in. 6 5 7 6 9 13 11 12 18 15 6 4 4 4 4 7 8 8 9 11 11 15 18 18 4 2 3 3 3 5 6 6 7 8 8 11 13 13 2 1 3 4 4 5 6 6 8 10 10 11 14 14 1 1/0 3 3 3 4 5 5 7 8 8 9 12 12 1/0 2/0 3 3 3 4 4 5 7 7 8 10 10 12 15 15 2/0 3/0 3 3 3 5 6 6 7 8 8 10 13 13 3/0 4/0 3 3 4 5 5 6 7 7 9 10 10 12 14 14 4/0 250 3 4 4 4 5 5 7 8 8 9 11 11 250 NATIONAL ELECTRICAL CODE 300 3 3 3 4 4 4 6 7 7 8 9 10 10 12 12 300 350 3 3 3 4 4 5 6 6 7 8 8 9 11 11 350 400 3 3 4 5 5 6 6 7 8 8 9 10 400 500 3 3 4 4 5 5 6 6 7 8 8 500 600 3 4 4 4 5 5 6 6 7 600 700 3 3 3 4 4 4 5 6 6 700 750 3 3 3 4 4 4 5 5 5 750 1000 3 3 3 4 4 4 1000 Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices (voids between strand wires) are virtually eliminated. CHAPTER 9 - TABLES AND EXAMPLES 70-829 Table 6. Dimensions of Lead-Covered Conductors Types RL, RHL, and THHW Single Two Three Conductor Conductor Conductor Size AWG Diam. Area Diam. Area Diam. Area kcmil Inches Sq. In. Inches Sq. In. Inches Sq. In. 14 .28 .062 .28 X .47 .115 .59 .273 12 .29 .066 .31 X .54 .146 .62 .301 10 .35 .096 .35 X .59 .180 .68 .363 8 sol. .41 .132 .41 X .71 .255 .82 .528 8 str. .43 .145 .43 X .75 .282 .86 .581 6 .49 .188 .49 X .86 .369 .97 .738 4 .55 .237 .54 X .96 .457 1.08 .916 2 .60 .283 .61 X 1.08 .578 1.21 1.146 1 .67 .352 .70 X 1.23 .756 1.38 1.49 1/0 .71 .396 .74 X 1.32 .859 1.47 1.70 2/0 .76 .454 .79 X 1.41 .980 1.57 1.94 3/0 .81 .515 .84 X 1.52 1.123 1.69 2.24 4/0 .87 .593 .90 X 1.64 1.302 1.85 2.68 250 .98 .754 2.02 3.20 300 1.04 .85 2.15 3.62 350 1.10 .95 2.26 4.02 400 1.14 1.02 2.40 4.52 500 1.23 1.18 2.59 5.28 The above cables are limited to straight runs or with nominal offsets equivalent to not more than two quarter bends. Note: No. 14 through No. 10, solid conductors; No. 8, solid or stranded conductors; Nos. 6 and larger, stranded conductors. 70-830 NATIONAL ELECTRICAL CODE Table 8. Conductor Properties Conductors DC Resistance at 75°C (167°F) Stranding Overall Size Area Copper Aluminum AWG/ Cir. Quan- Diam. Diam. Area Uncoated Coated ohm/ kcmil Mills tity In. In. In. ohm/kFT ohm/kFT kFT 18 1620 1 - 0.040 0.001 7.77 8.08 12.8 18 1620 7 0.015 0.046 0.002 7.95 8.45 13.1 16 2580 1 - 0.051 0.002 4.89 5.08 8.05 16 2580 7 0.019 0.058 0.003 4.99 5.29 8.21 14 4110 1 - 0.064 0.003 3.07 3.19 5.06 14 4110 7 0.024 0.073 0.004 3.14 3.26 5.17 12 6530 1 - 0.081 0.005 1.93 2.01 3.18 12 6530 7 0.030 0.092 0.006 1.98 2.05 3.25 10 10380 1 | 0.102 0.008 1.21 1.26 2.00 10 10380 7 0.038 0.116 0.011 1.24 1.29 2.04 8 16510 1 - 0.128 0.013 0.764 0.786 1.26 8 16510 7 0.049 0.146 0.017 0.778 0.809 1.28 6 26240 7 0.061 0.184 0.027 0.491 0.510 0.808 4 41740 7 0.077 0.232 0.042 0.308 0.321 0.508 3 52620 7 0.087 0.260 0.053 0.245 0.254 0.403 2 66360 7 0.097 0.292 0.067 0.194 0.201 0.319 1 83690 19 0.066 0.332 0.087 0.154 0.160 0.253 1/0 105600 19 0.074 0.373 0.109 0.122 0.127 0.201 2/0 133100 19 0.084 0.419 0.138 0.0967 0.101 0.159 3/0 167800 19 0.094 0.470 0.173 0.0766 0.0797 0.126 4/0 211600 19 0.106 0.528 0.219 0.0608 0.0626 0.100 250 - 37 0.082 0.575 0.260 0.0515 0.0535 0.0847 300 - 37 0.090 0.630 0.312 0.0429 0.0446 0.0707 350 - 37 0.097 0.681 0.364 0.0367 0.0382 0.0605 400 - 37 0.104 0.728 0.416 0.0321 0.0331 0.0529 500 - 37 0.116 0.813 0.519 0.0258 0.0265 0.0424 600 - 61 0.099 0.893 0.626 0.0214 0.0223 0.0353 700 - 61 0.107 0.964 0.730 0.0184 0.0189 0.0303 750 - 61 0.111 0.998 0.782 0.0171 0.0176 0.0282 800 - 61 0.114 1.03 0.834 0.0161 0.0166 0.0265 900 - 61 0.122 1.09 0.940 0.0143 0.0147 0.0235 1000 - 61 0.128 1.15 1.04 0.0129 0.0132 0.0212 1250 I 91 0.117 1.29 1.30 0.0103 0.0106 0.0169 1500 - 91 0.128 1.41 1.57 0.00858 0.00883 0.0141 -1750 - 127 0.117 1.52 1.83 0.00735 0.00756 0.0121 2000 - 127 0.126 1.63 2.09 0.00643 0.00662 0.0106 These resistance values are valid ONLY for the parameters as given. Using conductors having coated strands, different stranding type, and, especially, other temperatures changes the resistance. Formula for temperature change: R₂ = R₁ [1 + α(T₂ - 75)] where: αcu = 0.00323, αL = 0.00330. Conductors with compact and compressed stranding have about 9 percent and 3 percent, respectively, smaller bare conductor diameters than those shown. See Table 5A for actual compact cable dimensions. The IACS conductivities used: bare copper = 100%, aluminum = 61%. Class B stranding is listed as well as solid for some sizes. Its overall diameter and area is that of its circumscribing circle. (FPN): The construction information is per NEMA WC8-1976 (Rev 5=1980). The resistance is calculated per National Bureau of Standards Handbook 100, dated 1966, and Handbook 109, dated 1972. Table 9. AC Resistance and Reactance for 600 V Cables, 3-Phase 60, Hz, 75°C (167°F) - Three Single Conductors in Conduit Ohms to Neutral per 1000 feet XL (Reactance) AC Resistance for AC Resistance for Effective N at .85 PF for Effective Z at .85 PF for for All Wires Uncoated Copper Wires Aluminum Wires Uncoated Copper Wires Aluminum Wires Size Size AWG/ PVC, AI. Steel PVC AI. Steel PVC AI. Steel PVC AI. Steel PVC AI. Steel AWG/ kcmil Conduits Condult Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Condult Conduit Condult Conduit kcmil 14 .058 .073 3.1 3.1 3.1 - - - 2.7 2.7 2.7 14 12 .054 .068 2.0 2.0 2.0 3.2 3.2 3.2 1.7 1.7 1.7 2.8 2.8 2.8 12 10 .050 .063 1.2 1.2 1.2 2.0 2.0 2.0 1.1 1.1 1.1 1.8 1.8 1.8 10 8 .052 .065 0.78 0.78 0.78 1.3 1.3 1.3 0.69 0.69 0.70 1.1 1.1 1.1 8 6 .051 .064 0.49 0.49 0.49 0.81 0.81 0.81 0.44 0.45 0.45 0.71 0.72 0.72 6 4 .048 .060 0.31 0.31 0.31 0.51 0.51 0.51 0.29 0.29 0.30 0.46 0.46 0.46 4 3 .047 .059 0.25 0.25 0.25 0.40 0.41 0.40 0.23 0.24 0.24 0.37 0.37 0.37 3 2 .045 .057 0.19 0.20 0.20 0.32 0.32 0.32 0.19 0.19 0.20 0.30 0.30 0.30 2 1 .046 .057 0.15 0.16 0.16 0.25 0.26 0.25 0.16 0.16 0.16 0.24 0.24 0.25 1 1/0 .044 .055 0.12 0.13 0.12 0.20 0.21 0.20 0.13 0.13 0.13 0.19 0.20 0.20 1/0 2/0 .043 .054 0.10 0.10 0.10 0.16 0.16 0.16 0.11 0.11 0.11 0.16 0.16 0.16 2/0 3/0 .042 .052 0.077 0.082 0.079 0.13 0.13 0.13 0.088 0.092 0.094 0.13 0.13 0.14 3/0 4/0 .041 .051 0.062 0.067 0.063 0.10 0.11 0.10 0.074 0.078 0.080 0.11 0.11 0.11 4/0 250 .041 .052 0.052 0.057 0.054 0.085 0.090 0.086 0.066 0.070 0.073 0.094 0.098 0.10 250 300 .041 .051 0.044 0.049 0.045 0.071 0.076 0.072 0.059 0.063 0.065 0.082 0.086 0.088 300 CHAPTER 9 AND EXAMPLES 350 .040 .050 0.038 0.043 0.039 0.061 0.066 0.063 0.053 0.058 0.060 0.073 0.077 0.080 350 400 .040 .049 0.033 0.038 0.035 0.054 0.059 0.055 0.049 0.053 0.056 0.066 0.071 0.073 400 500 .039 .048 0.027 0.032 0.029 0.043 0.048 0.045 0.043 0.048 0.050 0.057 0.061 0.064 500 600 .039 .048 0.023 0.028 0.025 0.036 0.041 0.038 0.040 0.044 0.047 0.051 0.055 0.058 600 750 .038 .048 0.019 0.024 0.021 0.029 0.034 0.031 0.036 0.040 0.043 0.045 0.049 0.052 750 1000 .037 .046 0.015 0.019 0.018 0.023 0.027 0.025 0.032 0.036 0.040 0.039 0.042 0.046 1000 Notes: 1. These values are based on the following constants: UL-type RHH wires with Class B stranding, in cradled configuration. Wire conductivitites are 100% IACS copper and 61% IACS aluminum, and aluminum conduit is 45% IACS. Capacitive reactance is ignored, since it is negligible at these voltages. These resistance values are valid only at 75°C (167°F) and for the parameters as given, but are representative for 600-volt wire types operating at 60 Hz. 2. "Effective Z" is defined as R cos(theta) + X sin(theta), where "theta" is the power factor angle of the circuit. Multiplying current by effective impedance gives a good approximation for line-to-neutral voltage drop. Effective impedance values shown in this table are valid only at .85 power factor. For another circuit power factor (PF), effective impedance (Zc) can be calculated from R and XL values given in this table as follows: 70-831 Zc = R X PF + XL sin[arccos(PF)]. Table 10. Expansion Characteristics of PVC Rigid Nonmetallic Conduit Coefficient of Thermal Expansion = 3.38 x 10⁻⁵ in./in./°F 70-832 Length Change Length Change Length Change Length Change Temperature in Inches per Temperature in Inches per Temperature in Inches per Temperature in Inches per Change in 100 ft. of Change In 100 ft. of Change in 100 ft. of Change in 100 ft. of Degrees F PVC Conduit Degrees F PVC Conduit Degrees F PVC Conduit Degrees F PVC Conduit 5 0.2 55 2.2 105 4.2 155 6.3 10 0.4 60 2.4 110 4.5 160 6.5 15 0.6 65 2.6 115 4.7 165 6.7 20 0.8 70 2.8 120 4.9 170 6.9 25 1.0 75 3.0 125 5.1 175 7.1 30 1.2 80 3.2 130 5.3 180 7.3 35 1.4 85 3.4 135 5.5 185 7.5 40 1.6 90 3.6 140 5.7 190 7.7 45 1.8 95 3.8 145 5.9 195 7.9 50 2.0 100 4.1 150 6.1 200 8.1 NATIONAL ELECTRICAL CODE CHAPTER 9 - TABLES AND EXAMPLES 70-833 B. Examples Selection of Conductors. In the following examples, the results are generally expressed in amperes. To select conductor sizes, refer to the 0 to 2000 volt ampacity tables of Article 310 and the Notes that pertain to such tables. Voltage. For uniform application of Articles 210, 215, and 220, a nominal voltage of 120, 120/240, 240, and 208Y/120 volts shall be used in computing the ampere load on the conductor. Fractions of an Ampere. Except where the computations result in a major fraction of an ampere (0.5 or larger), such fractions shall be permitted to be I dropped. Ranges. For the computation of the range loads in these examples, Column A of Table 220-19 has been used. For optional methods, see Columns B and C of Table 220-19. Except where the computations result in a major fraction of a kilowatt (0.5 or larger), such fractions shall be permitted to be dropped. SI Units: For SI units: one square foot = 0.093 square meter; one foot = 0.3048 meter. Example No. 1(a). One-Family Dwelling The dwelling has a floor area of 1500 sq. ft., exclusive of unoccupied cellar, unfinished attic, and open porches. Appliances are a 12-kW range and a 5.5 kW, 240-volt dryer. Assume range and dryer kW ratings equivalent to kVA ratings in accordance with Sections 220-18 and 220-19. Computed Load [see Section 220-10(a)]: General Lighting Load: 1500 sq. ft. at 3 volt-amperes per sq. ft = 4500 volt-amperes. Minimum Number of Branch Circuits Required [see Section 220-4(b)]: General Lighting Load: 4500 volt-amperes ÷ 120 volts = 37.5 A: This requires three 15 A 2-wire or two 20 A 2-wire circuits Small Appliance Load: Two 2-wire 20 A circuits [see Section 220-3(b)] Laundry Load: One 2-wire 20 A circuit [see Section 220-4(c)] Minimum Size Feeder Required [see Section 220-10(a)]: General Lighting 4500 volt-amperes Small Appliance Load 3000 volt-amperes Laundry 1500 volt-amperes Total General Light and Small Appliance 9000 volt-amperes 3000 volt-amperes at 100% 3000 volt-amperes 9000 - 3000 = 6000 volt-amperes at 35% 2100 volt-amperes Net General Lighting and Small Appliance Load 5100 volt-amperes Range Load (see Table 220-19) 8000 volt-amperes Dryer Load (see Table 220-18) 5500 volt-amperes Total Load 18,600 volt-amperes For 120/240-volt 3-wire single-phase service or feeder, 18,600 volt-amperes ÷ 240 volts = 77.5 A. Net computed load exceeds 10kVA. Service conductors shall be 100 amperes [see