The table for calculating the cross-section of copper and aluminum cables according to the distance and intensity of the allowed current in the three-phase system with a nominal voltage of 380 volts in the conditions of the soil environment and a temperature of 20 degrees.

1000 900 800 700 600 500 400 450 350 300 250 200 150 100 50 10 aluminium copper
– – – – – – – – – – – – 5 7 15 27 – 1.5
– – – – – – – – – – – 6 8 12 25 36 – 2.5
– – – – – – – – – 6 8 10 13 20 40 46 – 4
– – – – 5 6 6.5 7 8 10 12 15 20 30 58 58 10 6
5 5 6 7 8 10 11 12 14 16 20 25 33 50 77 77 16 10
8 8 10 11 13 16 17 20 22 26 32 40 53 80 100 100 25 16
12 13 15 17 20 25 27 31 35 41 50 62 83 125 130 130 50 25
17 18 21 24 28 34 38 43 49 57 69 86 115 155 155 155 70 35
23 25 28 32 38 46 52 58 66 78 93 117 156 185 185 185 95 50
33 36 41 47 55 66 74 83 95 111 133 166 222 230 230 230 120 70
45 50 56 64 75 90 100 112 129 150 180 225 275 275 275 275 150 95
55 67 69 89 92 111 123 139 159 185 22 278 315 315 315 315 185 120
66 73 82 94 110 132 147 165 189 220 264 330 355 355 355 355 240 150
78 87 98 112 131 157 174 196 224 267 314 393 400 400 400 400 300 185
87 97 109 124 145 174 194 218 249 291 349 437 465 465 465 465 400 240
99 110 124 141 165 198 220 248 283 331 397 496 550 550 550 550 500 300

In choosing the appropriate cross-section, attention should be paid to both the voltage drop and the allowed current. Of course, for long distances, the voltage drop is the main factor. Both factors are considered in the above table. The maximum allowed current intensity in each row of the above table is in the environmental conditions of soil and temperature of 20 degreesIn case of temperature change, the maximum allowed current of each row must be modified according to the table below.

Allowable cable current

Cable current correction table with temperature for soil installation
temperature (C°) 10 15 20 25 30 35 40 45 50 55 60
The correction factor 1.10 1.05 1.00 0.95 0.89 0.84 0.77 0.71 0.63 0.55 0.45
Allowable current intensity of multi-core copper cables (without considering voltage drop) for installation in air at 30°C
Conductor cross section 240 185 150 120 95 70 50 35 25 16 10 6 4 2.5 1.5
Allowable current intensity 435 370 325 285 245 200 160 130 105 80 60 44 34 25 18