GB 50057-2010 第5.3.1条
| **** | **Down-conductor material**: For exposed down-conductors using hot-dip galvanized round steel, the diameter shall not be less than **8mm**; when flat steel is used, the cross-sectional area shall not be less than **48mm²** and the thickness shall not be less than **4mm**. When rebar within the building is used as a concealed down-conductor, the rebar diameter shall not be less than **10mm**, and it shall be welded or mechanically connected to form an electrical path. |