GB 50689-2011通信局(站)防雷与接地工程设计规范(英文版)
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3.3 Earth Electrode

3.3.1 The distance from the top of earth electrode to the ground should not be less than 0.7m.The earth electrodes at cold regions shall be buried under the frozen soil layer The burial depth of earth electrodes at stone mountains where soils are thinner or at broken stones and rocky regions shall be determined according to the specific conditions.

3.3.2 Hot dip galvanized steel,copper materials and copper-clad steel and the like with a length not less than 2.5m shall be adopted for making vertical earth electrodes,which may also be determined according to the soil property and geographical conditions where earth grids are buried.The spacing of vertical earth electrodes should not be less than 5m And the detailed quantity may be determined by the size of earth grids and geographical conditions.The earth grid shall be buried with vertical earth electrodes at junctions of its four corners.

3.3.3 In areas with high soil resistivity,in the case where it is difficult to satisfy the requirement on the earthing resistance of earth grid,the radial earth electrode may extend outward,or liquid long-acting resistance reducing agents,earth bars and external earthing and the like may also be adopted.

3.3.4 The earth bar may be used,when the normal earthing mode is not allowed as requested by the city environment.

3.3.5 Hot dip galvanized steel flats or copper materials shall be adopted for horizontal earth electrodes.The horizontal earth electrodes shall be connected with the vertical earth electrodes through welding.

3.3.6 When the hot dip galvanized steel is adopted for the earth electrode,the specification thereof shall comply with the following requirements:

1 The thickness of the steel tube shall not be less than 3.5mm.

2 The size of the steel angle shall not be less than 50mm×50mm×5mm.

3 The size of the steel flat shall not be less than 40mm×4mm.

4 The diameter of round steel shall not be less than 10mm.

3.3.7 When copper-clad steels,copper plating steel bars and copper plating round steels are adopted for earth electrodes,the diameter shall not be less than 10mm.The plating thickness of the copper plating steel bar and the copper plating round steel shall not be less than 0.254mm.

3.3.8 Except all soldering points among earth electrodes inside concrete,the anti-corrosion treatment shall be performed to all soldering points among other earth electrodes.

3.3.9 The weld length of the earth-termination system shall not be less than 2 times of its width in the case of using steel flat;it shall not be less than 10 times of its diameter in the case of using round steel.