American electricians handbook

Tai Lieu Chat Luong DIVISION FUNDAMENTALS Useful Tables Conversion Factors Graphical Electrical Symbols Principles of Electricity and Magnetism: Units Measuring, Testing, and Instruments Harmonics 1.1 1.2 1.9 1.12 1.21 1.70 1.100 USEFUL TABLES Natural Trigonometric Functions Angle (␪ or lag angle), deg Sine (or reactive factor) Cosine (or power factor) Tangent Cotangent Secant Cosecant Angle (␪ or lag angle), deg 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 0.00000 0.01774 0.03490 0.05234 0.06976 0.08715 0.10453 0.12187 0.13917 0.15643 0.17365 0.19081 0.20791 0.22495 0.24192 0.25882 0.27564 0.29237 0.30902 0.32557 0.34203 0.35837 0.37461 0.39073 0.40674 0.42262 0.43837 0.45399 0.46947 0.48481 0.50000 0.51504 0.52992 0.54464 0.55919 0.57358 0.58778 0.60181 0.61566 0.62932 0.64279 0.65606 0.66913 0.68200 0.69466 0.70711 1.00000 0.99985 0.99939 0.99863 0.99756 0.99619 0.99452 0.99255 0.99027 0.98769 0.98481 0.98163 0.97815 0.97437 0.97029 0.96592 0.96126 0.95630 0.95106 0.94552 0.93969 0.93358 0.92718 0.92050 0.91354 0.90631 0.89879 0.89101 0.88295 0.87462 0.86603 0.85717 0.84805 0.83867 0.82904 0.81915 0.80902 0.79863 0.78801 0.77715 0.76604 0.75741 0.74314 0.73135 0.71934 0.70711 0.00000 0.01745 0.03492 0.05241 0.06993 0.08749 0.10510 0.12278 0.14054 0.15838 0.17633 0.19438 0.21256 0.23087 0.24933 0.26795 0.28674 0.30573 0.32492 0.34433 0.36397 0.38386 0.40403 0.42447 0.44523 0.46631 0.48773 0.50952 0.53171 0.55431 0.57735 0.60086 0.62487 0.64941 0.67451 0.70021 0.72654 0.75355 0.78128 0.80978 0.83910 0.86929 0.90040 0.93251 0.96569 1.0000 Infinite 57.290 28.636 19.081 14.301 11.430 9.5144 8.1443 7.1154 6.3137 5.6713 5.1445 4.7046 4.3315 4.0108 3.7320 3.4874 3.2708 3.0777 2.9042 2.7475 2.6051 2.4751 2.3558 2.2460 2.1445 2.0503 1.9626 1.8807 1.8040 1.7320 1.6643 1.6003 1.5399 1.4826 1.4281 1.3764 1.3270 1.2799 1.2349 1.1917 1.1504 1.1106 1.0724 1.0355 1.0000 1.0000 1.0001 1.0006 1.0014 1.0024 1.0038 1.0055 1.0075 1.0098 1.0125 1.0154 1.0187 1.0223 1.0263 1.0306 1.0353 1.0403 1.0457 1.0515 1.0576 1.0642 1.0711 1.0785 1.0864 1.0946 1.1034 1.1126 1.1223 1.1326 1.1433 1.1547 1.1666 1.1792 1.1924 1.2062 1.2208 1.2361 1.2521 1.2690 1.2867 1.3054 1.3250 1.3456 1.3673 1.3902 1.4142 Infinite 57.299 28.654 19.107 14.335 11.474 9.5668 8.2055 7.1853 6.3924 5.7588 5.2408 4.8097 4.4454 4.1336 3.8637 3.6279 3.4203 3.2361 3.0715 2.9238 2.7904 2.6695 2.5593 2.4586 2.3662 2.2812 2.2027 2.1300 2.0627 2.0000 1.9416 1.8871 1.8361 1.7883 1.7434 1.7013 1.6616 1.6243 1.5890 1.5557 1.5242 1.4945 1.4663 1.4395 1.4142 180 179 178 177 176 175 174 173 172 171 170 169 168 167 166 165 164 163 162 161 160 159 158 157 156 155 154 153 152 151 150 149 148 147 146 145 144 143 142 141 140 139 138 137 136 135 1.2 Natural Trigonometric Functions Angle (␪ or lag angle), deg Sine (or reactive factor) Cosine (or power factor) Tangent Cotangent Secant Cosecant Angle (␪ or lag angle), deg 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 0.71934 0.73135 0.74314 0.75471 0.76604 0.77715 0.78801 0.79863 0.80902 0.81915 0.82904 0.83867 0.84805 0.85717 0.86603 0.87462 0.88295 0.89101 0.89879 0.90631 0.91354 0.92050 0.92718 0.93358 0.93969 0.94552 0.95106 0.95630 0.96126 0.96592 0.97029 0.97437 0.97815 0.98163 0.98481 0.98769 0.99027 0.99255 0.99452 0.99619 0.99756 0.99863 0.99939 0.99985 1.00000 0.69466 0.68200 0.66913 0.65606 0.64279 0.62932 0.61566 0.60181 0.58778 0.57358 0.55919 0.54464 0.52992 0.51504 0.50000 0.48481 0.46947 0.45399 0.43837 0.42262 0.40674 0.39073 0.37461 0.35837 0.34202 0.32557 0.30902 0.29237 0.27564 0.25882 0.24192 0.22495 0.20791 0.19081 0.17365 0.15643 0.13917 0.12187 0.10453 0.08715 0.06976 0.05234 0.03490 0.01745 0.00000 1.0355 1.0724 1.1106 1.1504 1.1917 1.2349 1.2799 1.3270 1.3764 1.4281 1.4826 1.5399 1.6003 1.6643 1.7230 1.8040 1.8807 1.9626 2.0503 2.1445 2.2460 2.3558 2.4751 2.6051 2.7475 2.9042 3.0777 3.2708 3.4874 3.7320 4.0108 4.3315 4.7046 5.1445 5.6713 6.3137 7.1154 8.1443 9.5144 11.430 14.301 19.081 28.634 57.290 Infinite 0.96569 0.93251 0.90040 0.86929 0.83910 0.80978 0.78128 0.75355 0.72654 0.70021 0.67451 0.64941 0.62487 0.60086 0.57735 0.55431 0.53171 0.50952 0.48773 0.46631 0.44523 0.42447 0.40403 0.38386 0.36397 0.34433 0.32492 0.30573 0.28647 0.26795 0.24933 0.23087 0.21256 0.19438 0.17633 0.15838 0.14054 0.12278 0.10510 0.08749 0.06993 0.05241 0.03492 0.01745 0.00000 1.4395 1.4663 1.4945 1.5242 1.5557 1.5890 1.6243 1.6616 1.7013 1.7434 1.7883 1.8361 1.8871 1.9416 2.0000 2.0627 2.1300 2.2027 2.2812 2.3662 2.4586 2.5593 2.6695 2.7904 2.9238 3.0715 3.2361 3.4203 3.6279 3.8637 4.1336 4.4454 4.8097 5.2408 5.7588 6.3924 7.1853 8.2055 9.5668 11.474 14.335 19.107 28.654 57.299 Infinite 1.3902 1.3673 1.3456 1.3250 1.3054 1.2867 1.2690 1.2521 1.2361 1.2208 1.2062 1.1922 1.1792 1.1666 1.1547 1.1433 1.1326 1.1223 1.1126 1.1034 1.0946 1.0864 1.0785 1.0711 1.0642 1.0576 1.0515 1.0457 1.0403 1.0353 1.0306 1.0263 1.0223 1.0187 1.0154 1.0125 1.0098 1.0075 1.0055 1.0038 1.0024 1.0014 1.0006 1.0001 1.0000 134 133 132 131 130 129 128 127 126 125 124 123 122 121 120 119 118 117 116 115 114 113 112 111 110 109 108 107 106 105 104 103 102 101 100 99 98 97 96 95 94 93 92 91 90 1.3 1.4 DIVISION ONE Fractions of Inch Reduced to Decimal Equivalents Halves ⁄2 4ths 8ths 16ths 32ds 64ths Decimal equivalents ⁄16 ⁄16 ⁄16 ⁄16 ⁄32 ⁄32 ⁄32 ⁄32 ⁄32 11 ⁄32 13 ⁄32 15 ⁄32 ⁄64 ⁄64 ⁄64 ⁄64 ⁄64 11 ⁄64 13 ⁄64 15 ⁄64 17 ⁄64 19 ⁄64 21 ⁄64 23 ⁄64 25 ⁄64 27 ⁄64 29 ⁄64 31 ⁄64 0.015625 0.03125 0.046875 0.0625 0.078125 0.09375 0.109375 0.125 0.140625 0.15625 0.171875 0.1875 0.203125 0.21875 0.234375 0.25 0.265625 0.28125 0.296875 0.3125 0.328125 0.34375 0.359375 0.375 0.390625 0.40625 0.421875 0.4375 0.453125 0.46875 0.484375 0.5 ⁄4 ⁄8 ⁄8 Halves 4ths 8ths 16ths ⁄16 11 ⁄16 13 ⁄16 15 ⁄16 ⁄4 ⁄8 ⁄8 32ds 64ths Decimal equivalents ⁄32 19 ⁄32 21 ⁄32 23 ⁄32 25 ⁄32 27 ⁄32 29 ⁄32 31 ⁄32 33 ⁄64 35 ⁄64 37 ⁄64 39 ⁄64 41 ⁄64 43 ⁄64 45 ⁄64 47 ⁄64 49 ⁄64 51 ⁄64 53 ⁄64 55 ⁄64 57 ⁄64 59 ⁄64 61 ⁄64 63 ⁄64 0.515625 0.53125 0.546875 0.5625 0.578125 0.59375 0.609375 0.625 0.640625 0.65625 0.671875 0.6875 0.703125 0.71875 0.734375 0.75 0.765625 0.78125 0.796875 0.8125 0.828125 0.84375 0.859375 0.875 0.890625 0.90625 0.921875 0.9375 0.953125 0.96875 0.984375 17 In figuring discounts on electrical equipment, it is often necessary to apply primary and secondary discounts By using the values in Table 4, time and labor may be conserved To find the net price, multiply the list or gross price by the multiplier from the table which corresponds to the discounts The discount on iron conduit may be quoted as 25 and 10 with percent for cash in 10 days To obtain the actual cost, 25 percent would be deducted from the list price, then 10 percent from that result, and finally percent from the second result If we assume that the list price of 1⁄2-in conduit is $12 per 100 ft, its actual price with the 25, 10, and percent discounts would be EXAMPLE $12.00 ⫺ 0.25 ⫻ $12.00 ⫽ $12.00 ⫺ $3.00 ⫽ $9.00 $9.00 ⫺ 0.10 ⫻ $9.00 ⫽ $9.00 ⫺ $0.90 ⫽ $8.10 $8.10 ⫺ 0.02 ⫻ $8.10 ⫽ $8.10 ⫺ $0.16 ⫽ $7.94 Therefore, the net cost of the conduit would be $7.94 per 100 ft Now by using the multiplier from Table corresponding to a primary discount of 25 percent and secondary discounts of 10 and percent, which is 0.661, $12.00 ⫻ 0.661 ⫽ $7.94 This is the same result as that obtained by using the longer method 1.5 FUNDAMENTALS Table for Figuring Total Discount Multiplier by Combining Primary and Secondary Discounts Secondary discounts Primary discount, percent 10 11 12 13 14 15 16 17 18 19 20 25 30 35 40 45 50 55 60 65 70 2% 5% 10% 15% and 2% 10 and 2% 10 and 5% 0.882 0.838 0.794 0.785 0.776 0.767 0.758 0.750 0.741 0.732 0.723 0.714 0.705 0.661 0.617 0.573 0.529 0.485 0.441 0.397 0.353 0.309 0.265 0.855 0.812 0.769 0.761 0.752 0.744 0.735 0.727 0.718 0.710 0.701 0.692 0.684 0.641 0.598 0.556 0.513 0.470 0.428 0.385 0.342 0.299 0.256 Multiplier 0.980 0.931 0.882 0.872 0.862 0.853 0.843 0.833 0.823 0.813 0.803 0.794 0.784 0.735 0.686 0.637 0.588 0.539 0.490 0.441 0.392 0.343 0.294 0.950 0.902 0.855 0.845 0.836 0.826 0.817 0.807 0.798 0.788 0.779 0.770 0.760 0.712 0.665 0.617 0.570 0.522 0.475 0.427 0.380 0.333 0.285 0.900 0.855 0.810 0.801 0.792 0.783 0.774 0.765 0.756 0.747 0.738 0.729 0.720 0.675 0.630 0.585 0.540 0.495 0.450 0.405 0.360 0.315 0.270 0.850 0.807 0.765 0.756 0.748 0.740 0.731 0.722 0.714 0.705 0.697 0.688 0.680 0.638 0.595 0.552 0.510 0.468 0.425 0.382 0.340 0.298 0.255 0.931 0.884 0.838 0.829 0.819 0.810 0.801 0.791 0.782 0.773 0.763 0.754 0.745 0.698 0.652 0.605 0.559 0.512 0.465 0.419 0.372 0.326 0.279 1.6 DIVISION ONE Multipliers for Computing Selling Prices Which Will Afford a Given Percentage Profit To obtain selling price, multiply actual cost (invoice cost ⫹ freight) by the following value To obtain selling price, multiply actual cost (invoice cost ⫹ freight) by the following value Percentage profit desired When percentage profit is based on cost When percentage profit is based on selling price Percentage profit desired When percentage profit is based on cost When percentage profit is based on selling price 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.053 1.064 1.075 1.087 1.100 1.111 1.124 1.136 1.149 1.163 1.176 1.190 1.204 1.220 1.235 1.250 1.267 1.283 1.299 1.316 1.334 1.352 1.370 1.390 1.409 1.429 1.450 1.471 1.493 1.516 1.539 36 37 38 39 40 41 42 43 45 46 47 48 49 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 90 100 1.36 1.37 1.38 1.39 1.40 1.41 1.42 1.43 1.45 1.46 1.47 1.48 1.49 1.50 1.52 1.54 1.56 1.58 1.60 1.62 1.64 1.66 1.68 1.70 1.72 1.74 1.76 1.78 1.80 1.90 2.00 1.563 1.588 1.613 1.640 1.667 1.695 1.725 1.754 1.818 1.852 1.887 1.923 1.961 2.000 2.084 2.174 2.272 2.381 2.500 2.631 2.778 2.941 3.126 3.333 3.572 3.847 4.168 4.545 5.000 10.000 Infinity 1.7 FUNDAMENTALS Table Showing Percentage Net Profit Percentage overhead Percentage markup above cost 10 15 20 25 30 331⁄3 35 40 45 50 55 60 65 70 75 80 85 90 95 100 NOTE 10% 12% 14% 16% 18% 20% 22% 24% Percentage net profit based on selling price for a given percentage overhead based on gross sales ⫺0.90 ⫺2.90 3.05 6.67 10.00 13.08 15.00 15.93 18.57 21.00 23.33 25.50 27.50 29.40 31.18 32.85 34.45 35.95 37.37 38.72 40.00 1.05 4.67 8.00 11.08 13.00 13.93 16.57 19.00 21.33 23.50 25.50 27.40 29.18 30.85 32.45 33.95 35.37 36.72 38.00 ⫺4.90 ⫺0.95 ⫺6.90 ⫺2.95 2.67 6.00 9.08 11.00 11.93 14.57 17.00 19.33 21.50 23.50 25.40 27.18 28.85 30.45 31.95 33.37 34.72 36.00 0.67 4.00 7.08 9.00 9.93 12.57 15.00 17.33 19.50 21.50 23.40 25.18 26.85 28.45 29.95 31.37 32.72 34.00 ⫺8.90 ⫺4.95 ⫺1.33 ⫺10.90 ⫺6.95 ⫺3.33 2.00 5.08 7.00 7.93 10.57 13.00 15.33 17.50 19.50 21.40 23.18 24.85 26.45 27.95 29.37 30.72 32.00 0.00 3.08 5.00 5.93 8.57 11.00 13.33 15.50 17.50 19.40 21.18 22.85 24.45 25.95 27.37 28.72 30.00 ⫺12.90 ⫺8.95 ⫺5.33 ⫺2.00 1.08 3.00 3.93 6.57 9.00 11.33 13.50 15.50 17.40 19.18 20.85 22.45 23.95 25.37 26.72 28.00 ⫺14.90 ⫺10.95 ⫺7.33 ⫺4.00 ⫺0.92 1.00 1.93 4.57 7.00 9.33 11.50 13.50 15.40 17.18 18.85 20.45 21.95 23.37 24.72 26.00 Minus (⫺) values indicate a net loss Net profits In figuring the net profit of doing business, Table will be found to be very useful The table may be used in three ways, as explained below To Determine the Percentage of Net Profit on Sales That You are Making Locate, at the top of one of the vertical columns, your percentage overhead—your ‘‘cost of doing business’’ in percentage of gross sales Locate, at the extreme left of one of the horizontal columns, your percentage markup The value at the intersection of these two columns will be the percentage profit which you are making If your cost of doing business is 18 percent of your gross sales and you mark your goods at 35 percent above cost, your net profit is 7.93 percent of gross sales, obtained by carrying down from the column headed 18 percent and across from the 35 percent markup EXAMPLE To Determine the Percentage Overhead Cost of Doing Business That Would Yield a Certain Net Profit for a Given Markup Percentage Locate in the extreme lefthand column the percentage that the selling price is marked above the cost price Trace horizontally across from this value until the percentage net profit desired is located At the top of the column in which the desired net profit is located will be found the percentage overhead cost of doing business that will allow this profit to be made 1.8 DIVISION ONE If the markup is 45 percent and the profit desired is 15 percent, an overhead cost of doing business of 16 percent can be allowed, obtained by carrying across from the 45 percent markup to the 15 percent profit and finding that this column is headed by 16 percent overhead EXAMPLE To Determine the Percentage That Should Be Added to the Cost of Goods to Make a Certain Percentage Net Profit on Sales Select the vertical column which shows the percentage cost of doing business at its top Trace down the column until the desired percentage profit is found; from this value trace horizontally to the extreme left-hand column, in which will be found the markup percentage—the percentage to be added to the cost to afford the desired profit It is desired to make a 12 percent net profit when the cost of doing business is 20 percent of gross sales Select the vertical column with 20 percent at its top Trace down the column to locate the net profit desired of 12 percent This will be partway between 11.00 and 13.33 Carrying across to the left from these values gives a required markup between 45 and 50, or approximately 47 percent For values which not appear in the table, approximate results can be obtained by estimation from the closest values in the table If more accurate results are desired for these intermediate values, the following formulas may be used: EXAMPLE P ⫽ 100 ⫺ h ⫺ 10,000 100 ⫹ m (1) 100(P ⫹ h) 100 ⫺ (P ⫹ h) or m⫽ or h ⫽ 100 ⫺ P ⫺ (2) 10,000 100 ⫹ m (3) where m ⫽ percentage markup based on cost of goods, h ⫽ percentage overhead based on gross sales, and P ⫽ percentage net profit based on selling price If you sell your goods at the retail list prices set by the manufacturers, you can use the table by converting the trade discount which you receive to an equivalent percentage markup, according to the following table: Manufacturer’s Discount Equivalent percentage Markup Manufacturer’s Discount Equivalent percentage Markup 10 15 20 25 30 11 171⁄2 25 331⁄3 43 35 40 45 50 54 662⁄3 813⁄4 100 Intermediate values may be calculated from the following formula: m⫽ 100Q 100 ⫺ Q (4) where m ⫽ percentage markup based on cost of goods and Q ⫽ manufacturer’s discount FUNDAMENTALS 1.9 CONVERSION FACTORS (Standard Handbook for Electrical Engineers) These factors were calculated with a double-length slide rule and checked with those given by Carl Hering in his ‘‘Conversion Tables.’’ 1 1 1 1 Length mil ⫽ 0.0254 mm ⫽ 0.001 in mm ⫽ 39.37 mils ⫽ 0.03937 in cm ⫽ 0.3937 in ⫽ 0.0328 ft in ⫽ 25.4 mm ⫽ 0.083 ft ⫽ 0.0278 yd ⫽ 2.54 cm ft ⫽ 304.8 mm ⫽ 12 in ⫽ 0.333 yd ⫽ 0.305 m yd ⫽ 91.44 cm ⫽ 36 in ⫽ ft ⫽ 0.914 m m ⫽ 39.37 in ⫽ 3.28 ft ⫽ 1.094 yd km ⫽ 3281 ft ⫽ 1094 yd ⫽ 0.6213 mi mi ⫽ 5280 ft ⫽ 1760 yd ⫽ 1609 m ⫽ 1.609 km Surface cmil ⫽ 0.7854 mil2 ⫽ 0.0005067 mim2 ⫽ 0.0000007854 in2 mil2 ⫽ 1.273 cmil ⫽ 0.000645 mm2 ⫽ 0.000001 in2 mm2 ⫽ 1973 cmil ⫽ 1550 mil2 ⫽ 0.00155 in2 cm2 ⫽ 197,300 cmil ⫽ 0.155 in2 ⫽ 0.00108 ft2 in2 ⫽ 1,273,240 cmil ⫽ 6.451 cm2 ⫽ 0.0069 ft2 ft2 ⫽ 929.03 cm2 ⫽ 144 in2 ⫽ 0.1111 yd2 ⫽ 0.0929 m2 yd2 ⫽ 1296 in2 ⫽ ft2 ⫽ 0.8361 m2 ⫽ 0.000207 acre m2 ⫽ 1550 in2 ⫽ 10.7 ft2 ⫽ 1195 yd2 ⫽ 0.000247 acre acre ⫽ 43,560 ft2 ⫽ 4840 yd2 ⫽ 4047 m2 ⫽ 0.4047 ⫽ 0.004047 km2 ⫽ 0.001562 mi2 mi2 ⫽ 27,880,000 ft2 ⫽ 3,098,000 yd2 ⫽ 2,590,000 m2 ⫽ 640 acres ⫽ 2.59 km2 1 1 1 1 10 Volume cmil 䡠 ft cm3 in3 ⫽ 0.0000094248 in3 ⫽ 0.061 in3 ⫽ 0.0021 pt (liquid) ⫽ 0.0018 pt (dry) ⫽ 16.39 cm3 ⫽ 0.0346 pt (liquid) ⫽ 0.0298 pt (dry) ⫽ 0.0173 qt (liquid) ⫽ 0.0148 qt (dry) ⫽ 0.0164 L or dm3 ⫽ 0.0036 gal ⫽ 0.0005787 ft3 pt (liquid) ⫽ 473.18 cm3 ⫽ 28.87 in3 pt (dry) ⫽ 550.6 cm3 ⫽ 33.60 in3 qt (liquid) ⫽ 946.36 cm3 ⫽ 57.75 in3 ⫽ gills (liquid) ⫽ pt (liquid) ⫽ 0.94636 L or dm3 ⫽ 0.25 gal liter (L) ⫽ 1000 cm3 ⫽ 61.025 in3 ⫽ 2.1133 pt (liquid) ⫽ 1.8162 pt (dry) ⫽ 0.908 qt (dry) ⫽ 0.2642 gal (liquid) ⫽ 0.03531 ft3 qt (dry) ⫽ 1101 cm3 ⫽ 67.20 in3 ⫽ pt (dry) ⫽ 0.03889 ft3 gal ⫽ 3785 cm3 ⫽ 231 in3 ⫽ 32 gills ⫽ pt ⫽ qt (liquid) ⫽ 3.785 L ⫽ 0.1337 ft3 ⫽ 0.004951 yd3 12.3 10 15 25 40 / 34 40 50 60 / 52 60 75 / 67 75 100 / 90 100 150 / 135 150 200 300 500 750 1000 1500 45 50 60 75 90 100 150 200 250 300 400 500 1000 1250 1500 Tungstenhalogen incandescent 13 14 15 20 30 40 90 Fluorescent (preheat) 17 30 / 25 30 32 40 / 32 40 / 34 40 Fluorescent (rapidstart, standard) 20 25 30 40 / 30 35 40 50 55 59 75 / 60 65 75 Fluorescent (slimline) Standard Sizes of Lamps for General Illumination, in Watts General incandescent 35 40 45 55 60 / 55 60 75 85 110 / 95 100 110 Fluorescent (rapid-start, high-output) 110 / 95 110 165 215 / 185 215 Fluorescent (rapidstart, 1500 mA) 40 50 75 100 175 250 400 1000 Mercury 32 50 70 100 150 175 250 400 1000 1500 Metal halide 35 50 70 100 150 200 250 310 400 1000 Highpressure sodium 12.4 DIVISION TWELVE Demand Loads for Household Electric Ranges, Wall-Mounted Ovens, Counter-Mounted Cooking Units, and Other Household Cooking Appliances over 13⁄4-kW Ratinga (Table 220.19, 2002 NEC) Column C to be used in all cases except as otherwise permitted in Note Demand factors (see Note 3), percent Maximum demand, kW (see Notes) Number of appliances Col A (less than 31⁄2 kW rating) Col B (31⁄2- to 83⁄4kW rating) Col C (not over 12 kW rating) 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26–30 31–40 41–50 51–60 61 and over 80 75 70 66 62 59 56 53 51 49 47 45 43 41 40 39 38 37 36 35 34 33 32 31 30 30 30 30 30 30 80 65 55 50 45 43 40 36 35 34 32 32 32 32 32 28 28 28 28 28 26 26 26 26 26 24 22 20 18 16 12 14 17 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 15 kW plus kW for each range 再 冎 ⁄ kW 再 for each range 冎 25 kW plus a Reprinted with permission from NFPA 70-2002 National Electrical Code威 Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts, 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety NOTE Over-12- to 27-kW ranges all of the same rating For ranges individually rated more than 12 kW but not more than 27 kW, the maximum demand in col C shall be increased by percent for each additional kilowatt of rating or major fraction thereof by which the rating of individual ranges exceeds 12 kW NOTE Over-83⁄4- to 27-kW ranges of unequal ratings For ranges individually rated more than 83⁄4 kW and of different ratings but none exceeding 27 kW, an average value of rating shall be calculated by adding together the ratings of all ranges to obtain the total connected load (using 12 kW for any range rated less than 12 kW) and dividing by the total number of ranges Then the maximum demand in col C shall be increased by percent for each kilowatt or major fraction thereof by which this average value exceeds 12 kW NOTE Over 13⁄4 kW through 83⁄4 kW In lieu of the method provided in col C, it shall be permissible to add the nameplate ratings of all household cooking appliances rated more than 13⁄4 kW but not more than 83⁄4 kW and to multiply the sum by the demand factors specified in col A or B for the given number of appliances Where the rating of cooking appliances falls under both Column A and Column B, the demand factors for each column shall be applied to the appliances for that column, and the results added together NOTE Branch-circuit load It shall be permissible to compute the branch-circuit load for one range in accordance with Table 220.19 The branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens, all supplied from a single branch circuit and located in the same room, shall be computed by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range NOTE This table also applies to household cooking appliances rated over 13⁄4 kW and used in instructional programs WIRING AND DESIGN TABLES 12.5 Demand Factors for Household Electric Clothes Dryersa (Table 220.18, 2002 NEC) Number of Dryers 10 11–13 14–19 20–24 25–29 30–34 35–39 40 up Demand Factors, Percent 100 100 100 100 80 70 65 60 55 50 45 40 35 32.5 30 27.5 25 a Reprinted with permission from NFPA 702002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety 3A Feeder Demand Factors for Kitchen Equipment Other Than Dwelling Unitsa (Table 220.20, 2002 NEC) Number of Units of Equipment and over Demand Factors, Percent 100 100 90 80 70 65 a Reprinted with permission from NFPA 702002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety 12.6 DIVISION TWELVE Demand Factors for General Lighting Loadsa (Table 220.3(A), 2002 NEC) Type of Occupancy Armories and auditoriums Banks Barbershops and beauty parlors Churches Clubs Courtrooms Dwelling unitsc Garages, Commercial (storage) Hospitals Hotels and motels, including apartment houses without provisions for cooking by tenantsc Industrial commercial (loft) buildings Lodge rooms Office buildings Restaurants Schools Stores Warehouses (storage) In any of the above occupancies except one-family dwellings and individual dwelling units of multifamily dwellings: Assembly halls and auditoriums Halls, corridors, and closets Storage spaces Unit Load Volt-amperes per Square Meter 11 39b 33 11 22 22 33 22 22 22 17 39 22 33 33 11 Unit Load per Ft2, Volt-amperes 31⁄2b 2 ⁄2 2 11⁄2 31⁄2b 3 ⁄4 1 ⁄2 ⁄4 a Reprinted with permission from NFPA 70-2002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety b In addition a unit load of W / ft2 shall be included for general-purpose receptacle outlets where the actual number of general-purpose receptacle outlets is unknown c See 220.3(B)(10) Data for determining National Electrical Code minimum allowable lighting and appliance loads: calculation of feeder loads The computed load of a feeder shall be not less than the sum of all branch-circuit loads supplied by the feeder, subject to the following provisions: GENERAL LIGHTING The demand factors listed in Table A shall apply to that portion of the total branch-circuit load computed for general illumination They shall not be applied in determining the number of branch circuits for general illumination See Pars and WIRING AND DESIGN TABLES 12.7 Lighting-Load Feeder Demand Factors A Portion of lighting load to which demand factor applies (volt-amperes) Demand factor, percent Dwelling units First 3000 or less at From 3001 to 120,000 at Remainder over 120,000 at 100 35 25 Hospitalsa First 50,000 or less at Remainder over 50,000 at 40 20 Hotels and motels including apartment houses without provision for cooking by tenantsa First 20,000 or less at From 20,001 to 100,000 at Remainder over 100,000 at 50 40 30 Warehouses (storage) First 12,500 or less at Remainder over 12,500 at 100 50 All others Total volt-amperes 100 Type of occupancy a The demand factors of this table shall not apply to the computed load of feeders or services to areas in hospitals, hotels, and motels where the entire lighting is likely to be used at one time, as in operating rooms, ballrooms, or dining rooms These demand factors are based on minimum load conditions and 100 percent power factor and in specific instances may not provide sufficient capacity for the installation contemplated In view of the trend toward higher-intensity lighting systems and increased loads because of the more general use of fixed and portable appliances, each installation should be considered with regard to the load likely to be imposed and the capacity increased to ensure safe operation When electric discharge lighting systems are to be installed, a high-power-factor type should be used; otherwise the conductor capacity may need to be increased SHOW-WINDOW LIGHTING For show-window lighting a load of not less than 600 volt-amperes/linear meter or 200 volt-amperes/linear foot shall be included for each linear foot of show window, measured horizontally along its base MOTORS For motors, a load computed according to the provisions of Secs to 13 shall be included NEUTRAL FEEDER LOAD The neutral feeder or service load shall be the maximum imbalance of the load determined by Sec The maximum unbalanced load shall be the maximum net computed load between the neutral and any one ungrounded conductor, except that the load thus obtained shall be multiplied by 140 percent for three-wire two-phase or five-wire two-phase systems For a feeder or service supplying household electric ranges, wall-mounted ovens, and countermounted cooking units, and electric dryers, the maximum unbalanced load shall be considered to be 70 percent of the load on the ungrounded conductors, as determined in accordance with Table 220.19 for ranges and Table 220.18 for dryers For three-wire dc or single-phase ac, four-wire three-phase, three-wire two-phase, or five-wire two-phase systems, a further demand factor of 70 percent may be applied to that portion of the unbalanced load in excess of 200 A There shall be no reduction of the neutral capacity for that portion of the load which consists of nonlinear loads supplied from a 4-wire, wye-connected, 3-phase system nor the grounded conductor of a 3-wire circuit consisting of two phase wires and the neutral of a 4-wire, 3-phase, wye-connected system 12.8 DIVISION TWELVE Fixed Electrical Space Heating The computed load of a feeder supplying fixed electrical space-heating equipment shall be 100 percent of the total connected load on all branch circuits Exception Where reduced loading of the conductors results from units operating on duty cycle, intermittently, or from all units not operating at one time, the authority enforcing the Code may grant permission for feeder or service conductors to be of a capacity less than 100 percent, provided the conductors are of sufficient capacity for the load so determined NONCOINCIDENT LOAD In adding the branch-circuit loads to determine the feeder or service load, the smaller of two noncoincident loads may be omitted from the total if it is unlikely that both loads will be served simultaneously SMALL APPLIANCES The computed branch-circuit load for receptacle outlets in other than dwelling occupancies, for which the allowance is not more than 180 VA per outlet, may be included with the general-lighting load and subject to the demand factors in Par 1, or may be computed at 100% for the first 100 kVA and the remainder at 50% demand factor DWELLING UNITS A dwelling unit is defined as one or more rooms for the use of one or more persons as a housekeeping unit with space for eating, living, and sleeping and permanent provisions for cooking and sanitation The requirements in Pars to 11 apply to dwelling-type occupancies and are supplemental to Pars to SMALL APPLIANCES a Dwelling units In dwelling units a feeder load of not less than 1500 VA for each two-wire circuit shall be included for small appliances (portable appliances supplied from receptacles of 15- or 20-A rating) in pantry and breakfast room, dining room, and kitchen Where the load is subdivided through two or more feeders, the computed load for each shall include not less than 1500 VA for each twowire circuit for small appliances These loads may be included with the generallighting load and subject to the demand factors in Par b Laundry circuit A feeder load of not less than 1500 VA shall be included for each two-wire laundry circuit This load may be included with the generallighting load and subject to the demand factors in Par ELECTRIC RANGES The feeder load for household electric ranges and other cooking appliances, individually rated more than 13⁄4 kW, may be calculated in accordance with Table To provide for possible future installations of ranges or higher ratings, it is recommended that when ranges of less than 83⁄4-kW ratings or wall-mounted ovens and counter-mounted cooking units are to be installed, the feeder capacity may be not less than the maximum demand value specified in col A of Table Where a number of single-phase ranges are supplied by a three-phase four-wire feeder, the current shall be computed on the basis of the demand of twice the maximum number of ranges connected between any two-phase wires See example in Sec 50 of Div 10 FASTENED-IN-PLACE APPLIANCES (OTHER THAN RANGES, CLOTHES DRYERS, AIR-CONDITIONING EQUIPMENT, OR SPACE-HEATING EQUIPMENT) When four or more fastened-in-place appliances other than electric ranges, clothes dryers, space heating or air-conditioning equipment, or space-heating equipment are connected to the same feeder or service in a one-family, two-family, or multifamily dwelling unit, a demand factor of 75 percent may be applied to the appliance load 12.9 WIRING AND DESIGN TABLES 11 SPACE HEATING AND AIR COOLING In adding branch-circuit loads for space heating and air cooling in dwelling units, the smaller of the two loads may be omitted from the total if it is unlikely that both loads will be used simultaneously 12 FARM BUILDINGS Feeders supplying farm buildings (excluding dwellings) or loads consisting of two or more branch circuits shall have minimum capacity computed in accordance with Table B B Method of Computing Farm Loads for Other Than Dwelling Units Load in Amperes at 240 V Loads expected to operate without diversity, but not less than 125 percent full-load current of the largest motor and not less than first 60 A of load Next 60 A of all other loads Remainder of other load Percent of Connected Load 100 50 25 For services to farm dwellings, see Pars to 11 For service at the main point of delivery to the farmstead, see Par 13 13 FARM SERVICES a Service-equipment and service-entrance conductors for individual farm buildings (excluding dwellings) shall have a minimum capacity computed in accordance with Par 12 b Minimum capacity of service conductors and service equipment, if any, at the main point of delivery to farms (including dwellings) shall be determined in accordance with the following formula: 100 percent of the largest demand computed in accordance with Par 12 75 percent of the second largest demand computed in accordance with Par 12 65 percent of the third largest demand computed in accordance with Par 12 50 percent of the demands of remaining loads computed in accordance with Par 12 NOTE Consider as a single computed demand the total of the computed demands of all buildings or loads having the same function NOTE The demand of the farm dwelling, if included in the demands of this formula, should be computed in accordance with Note of Table B NOTE NOTE Average Demand Factors for Motor Loadsa Number of motors 1–5 6–10 10–15 15–20 20–30 30–50 50–75 75–100 Above 100 6–10 Above 10 Character of load Demand factor Individual drives—tools, etc Individual drives—tools, etc Individual drives—tools, etc Individual drives—tools, etc Individual drives—tools, etc Individual drives—tools, etc Individual drives—tools, etc Individual drives—tools, etc Individual drives—tools, etc Group drives Group drives Fans, compressors, pumps, etc 1.00 0.75 0.70 0.65 0.60 0.50 0.45 0.40 0.40 0.85 0.70–0.45 1.00–0.85 a Permission for the use of a demand factor should be obtained from the authority enforcing the National Electrical Code 12.10 DIVISION TWELVE Full-Load Current in Amperes, Direct-Current Motorsa (Table 430.147, 2002 NEC) The following values of full-load currents b are for motors running at base speed Armature voltage ratingb hp 90 V 120 V 180 V 240 V 500 V 550 V 4.0 5.2 6.8 9.6 12.2 3.1 4.1 5.4 7.6 9.5 13.2 17 25 40 58 76 2.0 2.6 3.4 4.8 6.1 8.3 10.8 16 27 1.6 2.0 2.7 3.8 4.7 6.6 8.5 12.2 20 29 38 55 72 89 106 140 173 206 255 341 425 506 675 13.6 18 27 34 43 51 67 83 99 123 164 205 246 330 12.2 16 24 31 38 46 61 75 90 111 148 185 222 294 ⁄4 ⁄3 ⁄2 ⁄4 11⁄2 71⁄2 10 15 20 25 30 40 50 60 75 100 125 150 200 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 a Reprinted with permission from NFPA 70-2002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety b These are average direct-current quantities 12.11 WIRING AND DESIGN TABLES Full-Load Currents in Amperes, Single-Phase Alternating-Current Motorsa (Table 430.148, 2002 NEC) hp ⁄6 ⁄4 ⁄3 ⁄2 ⁄4 11⁄2 71⁄2 10 115 V 200 V 208 V 230 V 4.4 5.8 7.2 9.8 13.8 16 20 24 34 56 80 100 2.5 3.3 4.1 5.6 7.9 9.2 11.5 13.8 19.6 32.2 46 57.5 2.4 3.2 4.0 5.4 7.6 8.8 11 13.2 18.7 30.8 44 55 2.2 2.9 3.6 4.9 6.9 10 12 17 28 40 50 a Reprinted with permission from NFPA 70-2002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety These values of full-load currents are for motors running at usual speeds and motors with normal torque characteristics Motors built for especially low speeds or high torques may have higher full-load currents, and multispeed motors will have full-load currents varying with speed, in which case the nameplate current ratings shall be used The voltages listed are rated motor voltages The currents listed shall be permitted for system voltage ranges of 110 to 120 and 220 to 240 12.12 DIVISION TWELVE Average Full-Load Currents of Two-Phase Four-Wire Motorsa (Table 430.149, 2002 NEC) Induction-type squirrel-cage and wound-rotor, A hp ⁄2 ⁄4 11⁄2 71⁄2 10 15 20 25 30 40 50 60 75 100 125 150 200 115 V 230 V 460 V 575 V 2,300 V 4.8 6.4 11.8 2.4 3.2 4.5 5.9 8.3 13.2 19 24 36 47 59 69 90 113 133 166 218 270 312 416 1.2 1.6 2.3 4.2 6.6 12 18 23 29 35 45 56 67 83 109 135 156 208 0.8 1.0 1.3 1.8 2.4 3.3 5.3 10 14 19 24 28 36 45 53 66 87 108 125 167 14 18 23 28 32 43 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 a Reprinted with permission from NFPA 70-2002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety These values of full-load current are for motors running at speeds usual for belted motors and motors with normal torque characteristics Motors built for especially low speeds or high torques may require more running current, and multispeed motors will have full-load current varying with speed, in which case the nameplate current rating shall be used Current in common conductor of two-phase three-wire system will be 1.41 times value given The voltages listed are rated motor voltages Corresponding nominal system voltages are 110 to 120, 220 to 240, 440 to 480, and 550 to 600 V 12.13 WIRING AND DESIGN TABLES 10 Full-Load-Current Three-Phase Alternating-Current Motorsa (Table 430.150, 2002 NEC) Induction-type squirrel-cage and wound-rotor, A hp ⁄2 ⁄4 11⁄2 71⁄2 10 15 20 25 30 40 50 60 75 100 125 150 200 250 300 350 400 450 500 115 V 200 V 208 V 230 V 460 V 575 V 4.4 6.4 8.4 12.0 13.6 2.5 3.7 4.8 6.9 7.8 11.0 17.5 25.3 32.2 48.3 62.1 78.2 92 120 150 177 221 285 359 414 552 2.4 3.5 4.6 6.6 7.5 10.6 16.7 24.2 30.8 46.2 59.4 74.8 88 114 143.0 169 211 273 343 396.0 528.0 2.2 3.2 4.2 6.0 6.8 9.6 15.2 22 28 42 54 68 80 104 130 154 192 248 312 360 480 1.1 1.6 2.1 3.0 3.4 4.8 7.6 11 14 21 27 34 40 52 65 77 96 124 156 180 240 302 361 414 477 515 590 0.9 1.3 1.7 2.4 2.7 3.9 6.1 11 17 22 27 32 41 52 62 77 99 125 144 192 242 289 336 382 412 472 Synchronous-type unity power factor, Ab 2300 V 16 20 26 31 37 49 60 72 83 95 103 118 230 V 460 V 575 V 2300 V 53 63 83 104 123 155 202 253 302 400 26 32 41 52 61 78 101 126 151 201 21 26 33 42 49 62 81 101 121 161 12 15 20 25 30 40 a Reprinted with permission from NFPA 70-2002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety These values of full-load currents are typical for motors running at speeds usual for belted motors and motors with normal torque characteristics Motors built for especially low speeds (1200 RPM or less) or high torques may require more running current, and multispeed motors will have full-load currents varying with speed In these cases the nameplate current rating shall be used b For 90 and 80 percent power factor, the above figures shall be multiplied by 1.1 and 1.25, respectively The voltages listed are rated motor voltages The currents listed shall be permitted for system-voltage ranges of 110 to 120, 220 to 240, 440 to 480, and 550 to 600 V 12.14 11 DIVISION TWELVE Capacitor Ratings for Use with Three-Phase 60-Hz Motorsa Nominal motor speed, rpm 3600 1,200 1,800 Capacitor rating, kvar Line current reduction, % 14 12 11 1.5 2.5 10 9 12 14 17 100 125 150 200 250 300 350 400 450 500 Induction motor horsepower rating 71⁄2 10 15 20 25 30 40 50 60 75 900 720 600 Capacitor rating, kvar Line current reduction, % Capacitor rating, kvar Line current reduction, % 15 13 12 1.5 20 17 15 27 25 22 2.5 5.5 35 32 30 3.5 4.5 41 37 34 11 10 10 3.5 6.5 14 13 12 6.5 7.5 21 18 16 6.5 27 23 21 7.5 9.5 12 31 27 25 8 8 11 14 16 10 9 8 7.5 11 13 15 18 11 11 10 10 10 10 22 27 32.5 40 8 8 21 26 30 37.5 8 8 25 30 35 42.5 50 57.5 65 70 75 77.5 8 8 8 45 52.5 60 65 67.5 72.5 7 6 52.5 60 67.5 75 80 82.5 Capacitor rating, kvar Line current reduction, % 1.5 2.5 Capacitor rating, kvar Line current reduction, % Capacitor rating, kvar Line current reduction, % 10 12 15 18 21 15 14 13 12 11 10 11 12 15 19 22 26 20 18 16 15 15 14 14 16 20 24 27 32.5 23 22 20 19 19 18 9 9 27 32.5 37.5 47.5 10 10 10 10 32.5 40 47.5 60 13 13 12 12 40 47.5 52.5 65 17 16 15 14 8 8 8 57.5 65 75 85 92.5 97.5 9 9 70 80 87.5 95 100 107.5 11 11 10 10 9 77.5 87.5 95 105 110 115 13 12 11 11 11 10 䡠䡠䡠 a For use with three-phase 60-Hz NEMA Classification B motors to raise full-load power factor to approximately 95 percent 12 Minimum Ampacities for Conductors Supplying Motors Used for Short-Time, Intermittent, Periodic, or Varying Dutya (Table 430.22(E); Exception, 2002 NEC) Percentages of nameplate current rating Classification of service Short-time duty: operating valves, raising or lowering rolls, etc Intermittent duty: freight and passenger elevators, tool heads, pumps, drawbridges, turntables, etc (for arc welders, See 630.11 of the NEC) Periodic duty: rolls, ore- and coal-handling machines, etc Varying duty 5-min rating 15-min rating 30- and 60min rating Continuous rating 110 120 85 150 90 140 90 95 140 120 150 200 85 85 110 Reprinted with permission from NFPA 70-2002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety NOTE Any motor application shall be considered continuous-duty unless the nature of the apparatus it drives is such that the motor will not operate continuously with load under any condition of use a 12.15 WIRING AND DESIGN TABLES 13 Ampacities of Wires between Secondary Controller of Wound-Rotor Induction Motors and Resistors Resistor-Duty Classification Ampacity of Wire, Percent of Full-Load Secondary Current Light starting duty Heavy starting duty Extra-heavy starting duty Light intermittent duty Medium intermittent duty Heavy intermittent duty Continuous duty 35 45 55 65 75 85 110 14 Ampacities of Insulated Copper Conductors Used with Short-Time Rated Crane and Hoist Motors, Based on Ambient Temperature of 30ⴗC (86ⴗF), Up to Four Conductors in Raceway or Cable,a Up to acb or dca Conductors in Raceway or Cable (Table 610.14(A), 2002 NEC) Maximum operating temperature 75⬚C (167⬚F) 90⬚C (194⬚F) 125⬚C (257⬚F) Size AWG, kemil Types MTW, RHW, THW, THWN, XHHW, USE, ZW Types TA, TBS, SA, SIS, PFA, FEP, FEPB, RHH, THHN, XHHW, Z, ZW Types FEP, FEPB, PFA, PFAH, SA, TFE, Z, ZW 60 30 60 30 60 30 16 14 12 10 1/0 2/0 3/0 4/0 250 300 350 400 450 500 10 25 30 40 55 76 85 100 120 137 143 190 222 280 300 364 455 486 538 600 660 12 26 33 43 60 86 95 117 141 160 175 233 267 341 369 420 582 646 688 765 847 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 䡠䡠䡠 31 36 49 63 83 95 111 131 148 158 211 245 305 319 400 497 542 593 660 726 32 40 52 69 94 106 130 153 173 192 259 294 372 399 461 636 716 760 836 914 38 45 60 73 101 115 133 153 178 210 253 303 370 451 510 587 663 742 818 896 40 50 65 80 119 134 157 183 214 253 304 369 452 555 635 737 837 941 1042 1143 Maximum operating temperature Size AWG, kemil 16 14 12 10 1/0 2/0 3/0 4/0 250 300 350 400 450 500 12.16 DIVISION TWELVE 14 Ampacities of Insulated Copper Conductors Used with Short-Time Rated Crane and Hoist Motors, Based on Ambient Temperature of 30ⴗC (86ⴗF), Up to Four Conductors in Raceway or Cable,a Up to acb or dca Conductors in Raceway or Cable (Continued ) Types MTW, RHW, THW, THWN, XHHW, USE, ZW 60 30 Types TA, TBS, SA, SIS, PFA, FEP, FEPB, RHH, THHN, XHHW, Z, ZW Types FEP, FEBP, PFA, PFAH, SA, TFE, Z, ZW 60 60 30 30 Ampacity correction factors Ambient temp., ⬚C For ambient temperatures other than 30⬚C (86⬚F), multiply the ampacities shown above by the appropriate factor shown below Ambient temp., ⬚F 21–25 26–30 31–35 36–40 41–45 46–50 51–55 56–60 61–70 71–80 81–90 91–100 101–120 1.05 1.00 94 88 82 75 67 58 33 — — — — 70–77 79–86 88–95 97–104 106–113 115–122 124–131 133–140 142–158 160–176 177–194 195–212 213–248 1.05 1.00 94 88 82 75 67 58 33 — — — — 1.04 1.00 96 91 87 82 76 71 58 41 — — — 1.04 1.00 96 91 87 82 76 71 58 41 — — — 1.02 1.00 97 95 92 89 86 83 76 69 61 51 40 1.02 1.00 97 95 92 89 86 83 76 69 61 51 40 a For to simultaneously energized power conductors in raceway or cable, the ampacity of each power conductor shall be reduced to a value of 80 percent of that shown in the table b For to simultaneously energized 125⬚C (257⬚F) ac power conductors in raceway or cable, the amapcity of each power conductor shall be reduced to a value of 80 percent of that shown in the table NOTE Other insulations for general-wiring conductors approved for the temperature and location shall be permitted to be substituted for those shown in Table 14 The allowable ampacities of conductors used with 15-min motors shall be the 30-min ratings increased by 12 percent Reprinted with permission from NFPA 70-2002, National Electrical Code威, Copyright 䉷 2001, National Fire Protection Association, Quincy, Massachusetts 02269 This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety CONTACT CONDUCTORS following: The size of contact wires shall be not less than the Distance between End Strain Insulators or Clamp-Type Intermediate Supports Size of Wire Less than 9.0 m (30 ft) 9.10–18 m (30–60 ft) Over 18 m (60 ft) No No No 15 Curve for Determining Ampacities at 60 Hz of Bare ConcentricStranded Copper Conductors for 30ⴗC Rise over 40ⴗC Ambient For outdoor service, a 25 percent increase in ampacities is permissible WIRING AND DESIGN TABLES 12.17 16 Curve for Determining Ampacities for Weatherproof-Covered Concentric-Stranded Copper Conductors Installed outside Buildings 17 National Electrical Code allowable ampacities of conductors for all interior wiring (Tables 18 to 22, inclusive) EXPLANATION OF TABLES For an explanation of type letters and for the recognized size of conductors for the various conductor insulations, see Sec 310.13 in the NEC For installation requirements, see Sec 310.1 through 310.10 and the various articles of NEC 120 / 240-VOLT, 3-WIRE, SINGLE-PHASE DWELLING SERVICES AND FEEDERS For dwelling units, conductors, as listed below, shall be permitted to be utilized as 120 / 240-volt, 3-wire, single-phase service-entrance conductors, service lateral conductors, and feeder conductors that serve as the main power feeder to a dwelling unit and are installed in raceway or cable with or without an equipment grounding conductor For applications of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branchcircuit panelboard The feeder conductors to a dwelling unit shall not be required to be larger than its service-entrance conductors The grounded conductor shall be permitted to be smaller than the ungrounded conductors, provided the requirements of Sections 215.2, 220.22, and 230.42 of the NEC are met