Briefly explain how to set the lightning protection devices in school teaching buildings and student dormitories as follows:

The life safety and healthy growth of primary and secondary school students is an important link in national education, which is related to the long-term development of education and the stability and harmony of society. The State Ministry of Education and local education bureaus have issued many notices on the investigation and management of potential safety hazards in schools every year

, among which it is an important proposition whether lightning protection facilities are installed in teaching buildings and dormitory buildings and whether the facilities meet the requirements of national norms.

The lightning protection design of campus should be based on the design principle of "overall protection, advanced technology, economy and rationality, safety and reliability, and maintenance". According to the relevant provisions of Article 2.1.4 of GB51157-94(2111 edition), most teaching buildings in primary and secondary schools are identified as the third type lightning protection buildings, and a few are the second type lightning protection buildings.

(1) Lightning rod part

Each roof should be equipped with a circle of lightning protection belt along the eaves, which is installed at a distance of 31-51cm from the edge of the external wall. The support height of the lightning protection belt is 21cm, and 1 support frames are arranged every 1m, and the distance between the support frames at the corners is 1.5m. If necessary, a lightning protection short pin with a height of 1.5 m should be erected at the corners of the lightning protection belt for protection.

The lightning protection short pin is connected with the nearby lightning protection belt.

(2) Down lead part

One down lead is respectively arranged at the four corners of the teaching building, experimental building, apartment building, canteen, boiler room and other buildings, and the interval of down lead is arranged according to the building lightning protection category standard.

it is worth noting that the downlead should not be arranged at the entrance and exit, and a pair of disconnection cards should be installed at +1.8m for the downlead, and PVC pipes should be sleeved at-1.3m-+1.7m for mechanical protection.

(3) Grounding body part

The smaller the grounding resistance of the building, the better the lightning current is discharged, and the lower the damage degree caused by lightning stroke. In some special terrain, it is necessary to comprehensively consider the surrounding soil quality, soil layer structure, whether there are metal facilities or pipelines underground, and whether there are pedestrian passage areas on the ground.

if artificial grounding is used, it is composed of horizontal grounding body and vertical grounding body. The horizontal grounding body is made of 41*4 hot-dip galvanized flat steel, and the vertical grounding body is 51 * 51 * 5mm. One grounding body is installed every 5 m, and the joint is welded on both sides, and the welding area is not less than 11 mm..

note: flagpoles on campus should also be well grounded.

(4) Equipotential connection part

The metal facilities, pipes, radiation pipes and large metal objects on the roof of the teaching building, apartment building, canteen, dormitory and boiler room are connected with lightning protection facilities nearby. The connection mode is welding, and the welding place should be smooth, and there is no spot welding or virtual welding.

the length of single-sided welding is 1.2 times of the diameter of round steel, and the length of double-sided welding is 6 times of the diameter of round steel, and the welding place should be rusted.