The lightning protection of steel structure shall be provided by the electrical discipline. Generally, the lightning is led to the foundation underground through steel columns and embedded parts. Its specific work includes:
I. Arrangement of lightning arrester: according to the characteristics of light steel structure buildings, the roof of light steel structure buildings is obviously not suitable for installing tall and heavy lightning rods. On such buildings, the enclosure system of light steel structure buildings is non combustible. When metal plates are used as lightning arresters, the thickness should not be less than 0.5mm. The specification makes different requirements for the thickness of the metal plate according to the different conditions of whether there are combustibles under the metal plate, and clearly stipulates that "when there are no combustibles under the metal plate, its thickness shall not be less than 0.5mm".
II. Down lead: as long as a reliable grounding device is set, the steel column can be used as down lead according to the span. Of course, the specification has made requirements for the distance between downleads of various lightning protection buildings. However, during civil construction, as long as all steel columns, lightning arresters and grounding devices are reliably connected, they are downleads, and the actual effect exceeds the standard of the specification.
III. Layout of grounding device: in the current design, the foundation reinforcement is generally used as the natural grounding body, which is connected with galvanized flat steel, and the general equipotential connection is implemented. In this way, the grounding resistance is very small, and it is generally easy to meet the design requirements. However, it should be noted in the design that the grounding connecting plate should be reserved at a suitable position outdoors.
If the particularity of the grounding device of light steel structure building is ignored in the mining of steel structure, that is, the fact that the foundation reinforcement and grounding bolt are not electrically connected, the consequence is that the whole building has no reliable grounding grid. Of course, there are remedial measures for this situation. The remedial measure is to use galvanized flat steel as equipotential ring network. When galvanized flat steel passes through the steel column, it shall be reliably welded with the lower side of the column bottom baseboard. In this way, galvanized flat steel plays the dual role of grounding electrode and grounding wire. In addition to laying the equipotential grounding ring network along the periphery of the building for one week, the voltage equalizing grid should also be set in the building according to the span, which not only reduces the step voltage and protects personal safety, but also is conducive to the local equipotential connection of the production equipment in the industrial plant and shortens the length of the equipotential connection line.