First look at the construction process of lightning protection grounding engineering:
Grounding body → grounding trunk → underground conductor → lightning protection zone or pressure equalizing ring → bracket → lightning protection network → lightning rod
1. The lightning protection grounding system is composed of three parts: a lightning arrester, a down conductor, and a grounding body.
2. The lightning receptor has lightning rods, lightning protection nets, and lightning protection strips.
3, the lead laying method is divided into the Ming and dark settings.
4. The grounding device is divided into an artificial grounding body and a natural grounding body.
The following examples will fully analyze the lightning protection construction process and share it with everyone.
The outdoor grounding wire must be a hot-dip galvanized material. The thickness of the grounded flat iron must not be less than 4mm, and the cross-sectional area must not be less than 100mm2.
Flat steel and flat steel overlap is twice the width of the flat steel, not less than three sides welding; round and round steel overlap for the round diameter of 6 times, double-sided welding; round steel and flat steel lap 6 times the diameter of round steel, double-sided welding; flat steel and steel pipe, flat steel and angle steel welding, close to the outside of the angle steel on both sides, or close to the 3/4 steel pipe surface, upper and lower welding.
When the floor steel mesh is used as the ground connection line, the hot-dip galvanized round steel not less than Φ12 shall be used for the ground-spanning rebar; the weld joint shall be full and have sufficient mechanical strength, and shall not contain slag inclusions, biting meat, cracks, cold welding, Holes and other defects, the welding of the skin to knock the net.
Threaded bridges
When the main ribs of the column are used as lightning deflectors, when the main ribs are threaded, both ends of the threaded connection should be bridged.
Smooth welding, no slag addition, biting meat, welding
Total equipotential tank, must be clearly marked
Label textual description
Grounding flat iron should be straightened before laying. Laying should be laid upright, and should not be placed flat, because the dispersion resistance is small when erecting; the welding length should be twice the width of the flat iron, and 3 surface welding should be adopted. After welding, it should be removed. The medicinal skin and flat iron laid inside the plain must be painted with asphalt for antiseptic treatment.
Grounding flat iron cross connection
Grounding flat iron T-connect
When using the main ribs (not less than Φ12mm in diameter) of the structural column as the lightning deflector, during the rebar tying of each layer, find all required main ribs and mark them with paint according to the requirements of the design drawings.
The bending point of the lightning conductor shall not be less than 90o, the bending radius shall not be less than 10 times the diameter of the round steel, and the bracket of the turning part shall not be greater than 0.3m. Welds should be full and have sufficient mechanical strength. The skin of the welds should be knocked clean. After welding, two anti-rust paints and two top coats (silver paint) shall be applied.
Welding must not have slag inclusions, biting meat, cracks, imaginary welds, porosity, etc.
If the roof air-termination device uses a concrete bearing, the concrete bearing shall be placed in a sub-file, and a straight line shall be drawn between the supports at both ends, and then the other bearings shall be straightened with a cement mortar, the distance shall not be greater than 1.5 meters; when the roof is pure In the waterproof layer, a rubber pad with a thickness of not less than 3mm should be placed under the support to prevent damage to the waterproof layer.
When using a hot-dip galvanized round steel, the lap length is six times the diameter of the round steel and it shall be welded on both sides. If a hot galvanized flat steel is used as a lightning receptor, the lap length should not be less than its width. 2 times, at least 3 edges are welded. When placing, it must be placed flat when buried and buried. Welds at the welding area should be full and have sufficient mechanical strength. There should be no slag, biting meat, cracks, voids, porosity Such defects, the welding of the skin to knock on the net, after welding must be brushed antirust two, topcoat (silver paint) two.
The concealed test points are generally 0.5 meters away from the ground and should generally be marked with the black marks as shown in the figure; at the temporary grounding point for inspection, the white primer and the black mark should be brushed, and the board surface should be decorated with the structure. Face flush, straight and not skewed.
Test point ID
Test point practice
The installation of the lightning protection nets should be straight and firm, and the steel bars should not be subject to undulation and bending, and the total horizontal and vertical deviations should not exceed 10 mm. The steel bars and accessories are all hot-dip galvanized parts. The lightning protection support parts are firm and can withstand a drawing force greater than 49N (5Kg) with uniform spacing. The distance between the straight parts is not more than 1m. The root surface of the support piece is smooth and has a good look and feel.
There are projections on the roof of the building, such as metal flag poles, breathable pipes, metal gutters, iron railings, ladders, cooling towers, television antennas, etc. Metal conductors in these parts must be welded to the lightning protection network.
When the cast iron metal pipe protruding from the roof is used as a lightning arrester, the pipe hanger and the lightning protection installation attachment are connected.
The installation of the lightning protection nets should be straight and the steel bars should be free from bending. The allowable deviation of the inspection section per 2 meters of flatness should be 3/1000, and the total length should be no more than 10mm. The steel bars and accessories are all hot-dip galvanized parts. The specifications of the steel bars meet the design requirements and are firmly fixed. The lightning protection support pieces are fixed and fixed, and the spacing is even. The distance between the straight lines is not more than 1m. The root surface of the support piece is flat and smooth. The round steel diameter must not be less than 8mm.
The lightning conductor must be straightened before it can be laid. The bend should not be less than 90° and must not be bent into a dead angle. In addition to the special requirements of the lead-off line design, galvanized flat steel section shall not be less than 48mm2, the diameter of galvanized round steel shall not be less than Φ8mm.
Lightning deflector marking
The distance between the supports must be uniform, and the distance between the fulcrum points of the horizontal straight portion should not exceed 1m, the vertical portion should not exceed 1.5m, the bending portion should be 0.3m to 0.5m, and the mounting height of the bracket should be 100 to 200mm.
When the lightning rod is installed, the bottom plate of the steel plate is fixed on the embedded anchor bolts, and a rib plate is welded. The lightning rod is erected, straightened, aligned, and then spot welded. Then, the spot welding is corrected and the other three are welded. Block ribs, and finally the lightning deflector welded to the bottom plate, remove the paint brush anti-rust paint and silver paint two.
Lightning connection of roof metal components
The roof lightning conductors should be straight and firm. There should be no undulation and bending. The roof should be the same as the building roof. When the roof of the building has a curve, the lightning protection net should be laid along with the curve of the roof of the building; when the roof is covered with a lightning protection net, it is important. The building can use 10m*10m grids, and general buildings use 20m*20m grids, except for special design requirements.
The lightning receptor shall make lightning protection compensation measures at the deformation joints of the building
The grounding mains shall be provided with test points prefabricated for the test of grounding resistance. The cover shall be secured with a detachable screw nut. The cover must be grounded. The grounding symbol and the text description are generally specified as black.
The exterior surface of the equipotential tank must meet the aesthetic requirements for architectural decoration. There must be an “equipotential bonding terminal box, not touchable†logo on the box door (cover plate). The color is black. The door should be flush with the decorative surface, not skewed or polluted.
Box connection terminal board
In the bathroom for equipotential bonding, the local connection should be made with the terminals in the equipotential terminal box LEB. The toilet shall be provided with an equal potential terminal box at a distance of 0.3m from the ground, and shall be reliably connected to the ground wire of the metal pipe and metal appliance using a PVC16 pipe and BVR-4? copper wire (yellow-green two-color). Each connection line shall be separated from the equal potential terminal box. Outgoing, after the grounding line is connected, the wall leads out of the nozzle and the junction box to timely block or cover.
Transformer-distribution-room-grounded grounding mains installation: When laid horizontally along the walls of the building, the height from the ground is 250-300mm, and the height is uniform; the distance from the building wall is 10-15mm, and the spacing is uniform. (From weak electricity industry network)
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