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The guidelines for current carrying capacities of copper and aluminum are valid DIN VDE 0265 and 0276 part 1000.
The current carrying capacity of a cable should be limited in such a degree that at all locations in a cable system which causes the generated heats under given proportions to lead safely in the environment. The
heat flow depends on the inner heat-resistance between conductor and outer surface of the cable and as well as from the heat emission to the surroundings.
For cables laid in earth, the assumption for the calculation are chosen in a way that the given values for current loading at normal operation can be used in most of the cases without conversion.
For single cables laid directly in earth at EVU-Loading and a specific earth heat-resistance of 100 K x cm/W, mostly of the soil conditions are to be taken into consideration.
Calculation basis
| EVU-load (current loading grade) |
0.7 (1.0 for air) |
| Specific earth heat-resistance |
100 K x cm/W |
| Specific heat-resistance of the insulation and jacket |
600 K x cm/W |
| Bedding depth in earth |
0.7 m |
| Earth temperature |
20°C |
| Ambient temperature in the air |
30°C |
Current carrying capacity of 3-, 4- and multi conductor (5 conductors and more) cables at ambient temperature of 20°C in earth, 30°C for the air.
Current carrying capacity in ampere (A):
Cross-section
in mm² |
3 & 4-conductor cables |
5 to 61 conductor cables |
Ground
A |
Air
A |
Ground
A |
Air
A |
| 1.5 |
28 |
18.5 |
Number of loading conductors and conversion factors from 1.5 to 10 mm² see following table |
| 2.5 |
37 |
27 |
| 4 |
48 |
36 |
| 6 |
60 |
45 |
| 10 |
80 |
62 |
| 16 |
103 |
81 |
| 25 |
134 |
110 |
| 35 |
162 |
134 |
| 50 |
192 |
163 |
| 70 |
235 |
205 |
| 95 |
283 |
253 |
| 120 |
323 |
294 |
| 150 |
363 |
334 |
| 185 |
412 |
386 |
| 240 |
478 |
457 |
| 300 |
542 |
529 |
| 400 |
615 |
610 |
Current loading for multi conductor cables (5 conductors and more)
The current loading of each conductor for cables with a conductor cross-section of 1,5 to 10 mm2, depends on the number of conductors and the number of loaded conductors respectively and is calculated by means of
the following conversion factors.
The conversion factors according to the number of loaded conductors are to be multiplied with the loading values of the above table.
| Number of loading conductors |
Conversion factors for the value 1.5 to 10 mm² |
| Ground |
Air |
| 5 |
0.70 |
0.75 |
| 7 |
0.60 |
0.65 |
| 10 |
0.50 |
0.55 |
| 14 |
0.45 |
0.50 |
| 19 |
0.40 |
0.45 |
| 24 |
0.35 |
0.40 |
| 40 |
0.30 |
0.35 |
| 61 |
0.25 |
0.30 |
Note
During the installation in earth or in the air, for the operation and the laying performance occur any deviations or unfavorable relations (e.g. bundling of cables, in the wall, under plaster, on the wall or on
trays, on cable troughs or on cable racks), the specified conversion factors to DIN VDE 0276 part 1000 table 12 and 13 must be taken into consideration.
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All-weather, Rubber & Welding
