|
|
|
|
|
| Earthing Resistance | ||
|
|
|
|
|
| Principle of Operation | ||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Type of | Soil Re- |
| Earthing Resistance (Ω) |
| |||
| sitivity |
|
|
|
|
|
| |
| Soil | [ρE] | Earthing Rod m | Earthing Strip m | ||||
|
|
| Depth |
| ||||
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
| Ω.m | 3 | 6 | 10 | 5 | 10 | 20 |
|
|
|
|
|
|
|
|
|
| Moist | 30 | 10 | 5 | 3 | 12 | 6 | 3 |
| humus |
|
|
|
|
|
|
|
| soil, |
|
|
|
|
|
|
|
| moor soil, |
|
|
|
|
|
|
|
| swamp |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Farming | 100 | 33 | 17 | 10 | 40 | 20 | 10 |
| soil,loam |
|
|
|
|
|
|
|
| y and |
|
|
|
|
|
|
|
| clay soils |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Sandy | 150 | 50 | 25 | 15 | 60 | 30 | 15 |
| clay soils |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Moist | 300 | 66 | 33 | 20 | 80 | 40 | 20 |
| sandy |
|
|
|
|
|
|
|
| soil |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Dry | 1000 | 330 | 165 | 100 | 400 | 200 | 100 |
| sandy |
|
|
|
|
|
|
|
| soil |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Concrete | 400 |
|
|
| 160 | 80 | 40 |
| 1 : 5* |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Moist | 500 | 160 | 80 | 48 | 200 | 100 | 50 |
| gravel |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Dry | 1000 | 330 | 165 | 100 | 400 | 200 | 100 |
| gravel |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Stoney | 30000 | 1000 | 500 | 300 | 1200 | 600 | 300 |
| soil |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Rock | 107 | - | - | - | - | - | - |
|
|
|
|
|
|
|
|
|
* for concrete mixtures 1 : 7 the values have to be increased by 24 %
75
