Substituting the given value in formula (5)
350 × 200 × 21.6 circular mils = —————————————————— = 201,600. 7.5
Diameter = 2 √201,600 = 449 circular mils or .449 in.
From the table (on page 731 or on page 742) the nearest (=larger=) size of wire is 0000 B. & S. gauge.[4]
[4] =CAUTION.=—The size thus obtained should be compared with the table of carrying capacity of wires as given on page 731 to see if the wires would have to carry more than the allowable current.
WIRING TABLE FOR LIGHT AND POWER CIRCUITS
===================+======================================================= VOLTS | PERCENTAGE OF LOSS ===================+======================================================= 2000 | 1.7 1.5 1.4 1.2 1.1 1.0 0.75 0.5 1000 | 3.4 2.9 2.7 2.4 2.2 2.0 1.5 1.0 500 | 6.5 5.7 6.2 4.8 4.3 3.9 2.9 2.0 220 | 13.7 12.0 11.0 10.3 9.3 8.3 6.5 4.4 110 | — — 20.0 18.5 17.0 15.4 12.0 8.4 52 | — — — — — — 22.4 16.1 ===================+======================================================= ACTUAL VOLTS LOST =========+=========+======================================================= Carrying | | Capacity | Size | 35 30 27.5 25 22.5 20 15 10 Amperes. | B. & S. | =========+=========+======================================================= 300 | 0000 | 345800 296400 271700 247000 222300 197600 148200 98800 245 | 000 | 274400 235200 215600 196000 176400 156800 117600 78400 215 | 00 | 217525 186450 170912 155375 139837 124300 93225 62150 190 | 0 | 172550 147900 135575 123250 110925 98600 73950 49300 160 | 1 | 136850 117300 107525 97750 87975 78200 58650 39100 135 | 2 | 108500 93000 85250 77500 69750 62000 46500 31000 115 | 3 | 86100 73800 67650 61500 55350 49200 36900 24600 100 | 4 | 68250 58500 53625 48750 43875 39000 29250 19500 90 | 5 | 54250 46500 42625 38750 34875 31000 23250 15500 80 | 6 | 43050 36900 33825 30750 27675 24600 18450 12300 60 | 8 | 26965 23130 21202 19275 17347 15420 11565 7710 40 | 10 | 16975 14550 13337 12125 10912 9700 7275 4850 30 | 12 | 10675 9150 8388 7625 6862 6100 4575 3050 22 | 14 | 6720 5760 5280 4800 4320 3840 2880 1920 5[5] | 16 | 4235 3630 3328 3025 2723 2420 1815 1210 ————————-+————————-+——————————————————————————————————————————————————————-
===================+===================================================== VOLTS | PERCENTAGE OF LOSS ===================+===================================================== 2000 | 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 1000 | 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 500 | 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 220 | 3.9 3.5 3.1 2.7 2.2 1.8 1.4 0.9 0.45 110 | 7.6 6.8 6.0 5.2 4.4 3.5 2.7 1.8 0.9 52 | 14.7 13.3 11.8 10.3 8.8 7.1 5.5 3.7 1.9 ===================+===================================================== ACTUAL VOLTS LOST =========+=========+===================================================== Carrying | | Capacity | Size | 9 8 7 6 5 4 3 2 1 Amperes. | B. & S. | =========+=========+===================================================== 300 | 0000 | 88920 79040 69160 59280 49400 39520 29640 19760 9880 245 | 000 | 70560 62720 54880 47040 39200 31360 23520 15680 7840 215 | 00 | 55935 49720 43505 37290 31075 24860 18645 12430 6215 190 | 0 | 44370 39440 34510 29580 24650 19720 14790 9860 4930 160 | 1 | 35190 31280 27370 23460 19550 15640 11730 7820 3910 135 | 2 | 27900 24800 21700 18600 15500 12400 9300 6200 3100 115 | 3 | 22140 19680 17220 14760 12300 9840 7380 4920 2460 100 | 4 | 17550 15600 13650 11700 9750 7800 5850 3900 1950 90 | 5 | 13950 12400 10850 9300 7750 6200 4650 3100 1550 80 | 6 | 11070 9840 8610 7380 6150 4920 3690 2460 1230 60 | 8 | 6939 6168 5397 4626 3855 3084 2313 1542 771 40 | 10 | 4365 3880 3395 2910 2425 1940 1455 970 486 30 | 12 | 2745 2440 2135 1830 1525 1220 915 610 305 22 | 14 | 1728 1536 1344 1152 960 768 576 384 192 5[5] | 16 | 1089 968 847 726 605 484 363 242 121 ————————-+————————-+————————————————————————————————————————————————————-