As laying depth, the mathematical distance to the cable axis - for triangular bunched laying the distance of the bundle axis to the ground surface with 70 cm is chosen. With increased laying depth the load
ratings will be mathematically reduced. Hereby the same temperature and the same thermal earth resistance are to be presumed. Normal operation conditions and indications for deviating operation conditions:
| Laid in ground |
Laid in air |
|
1 Multi Conductor Cable
|
 |
1 Multi Conductor Cable
|
|
| 1 Single Conductor Cable in direct current system |
 |
1 Single Conductor Cable in direct current system |
|
| 3 Single Conductor Cables in 3-phase system, side by side, with a space of 7 cm / 2.76" |
 |
3 Single Conductor Cables in 3-phase system, side by side, with a space of a cable Ø |
|
| 3 Single Conductor Cables in 3-phase system, in bundle form |
 |
3 Single Conductor Cables in 3-phase system, in bundle form |
|
| Bedding in ground and if necessary covering with bricks, cement plates or coverings made of plastic |
 |
Laid in open air, i.e. unhindered heat radiation will be ensured at: Distance of cable from wall, floor or ceiling ≥ 2 cm / 0.79"
|
|
|
Ambient conditions
Ground temperature at installation depth:
20°C
Soil-thermal resistance
of moist area:
1.0 K x m/W
Soil-thermal resistance of dry area:
2.5 K x m/W
Connecting and Grounding
of metal jackets or shielding on both ends
|
For cables laying side by side: Space at least two times of the cable ø
For cables laying one above the other:
Vertical space of the cable at least two times of the cable ø
cable length at least 30 cm
Consideration of thermal loss in cable, the increased air temperature of sufficient big and ventilated rooms
Protection against direct heat radiation of sunlight etc.
Air temperature 30°C
Adequate big or ventilated rooms, due to that the power loss of the cable not be noticeable increased
Connecting and Grounding
of metal jackets or shielding on both ends |
|
Conversion factors for laying in earth:
covering hood with air cavat y = 0.9
laid in conduit = 0.85
Conversion factors
for laying in air:
alternating ambient
temperatures
as of collecting laying
conditions
for laying in conduits
see tables and
indications according
to DIN VDE 0298
|
All-weather, Rubber & Welding
