Lightning protection induction of lightning protection buildings of the first kind

Lightning is mainly divided into direct lightning and induced lightning, among which the first type of lightning protection buildings should do a good job of lightning protection while protecting against direct lightning.

1. Equipment, pipes, structures, cable metal sheaths, steel roof trusses, steel windows and other large metal objects in the building and metal objects such as radiation pipes and air ducts protruding from the roof shall be connected to the grounding device for lightning protection; The metal roof should be grounded once every 18-24 meters; For the reinforced concrete roof poured on site or made of prefabricated parts, the intersection of steel mesh should be bound or welded, and the down lead should be used for grounding every 18-24 meters.

2. When the clear distance of long metal objects such as pipes, frames and cables laid in parallel is less than 100mm, metal wires should be used for jumper, and the distance between jumper points should not be greater than 30 m; When the cross clearance is less than 100mm, the intersection should also be bridged. When the transition resistance of elbows, valves, flanges and other joints of metal objects is greater than 0.03Ω, the joints shall be bridged by metal wires. For flanges with not less than 5 bolts, it is not necessary to cross over in a non-corrosive environment.

3. The grounding device against lightning induction should be shared with the grounding device of electrical and electronic systems, and its power frequency grounding resistance should not be greater than 10Ω. The distance between the grounding device against lightning induction and the grounding device of independent lightning rod, overhead lightning wire or overhead lightning net should be calculated according to the formula, and the distance should be not less than 3 meters. When there is an equipotential grounding trunk line in the house, it shall be connected to the lightning protection induction grounding device at least two times.