Lightning protection and grounding is an important sub-division project in construction electrical engineering. Due to its strong professionalism and many hidden projects, it is often a difficulty in construction projects. This article explains in detail the 15 process nodes of lightning protection and grounding construction. attaches examples of excellent project pictures for your reference to guide construction or inspection.
Lightning protection down conductor
Process description: The welding of grounding device should be lap welding, and the lap length should comply with the following regulations: Flat steel and flat steel overlap shall be twice the width of the flat steel, no less than three sides Welding; The overlap between round steel and round steel is 6 times the diameter of the round steel, double-sided welding; the overlap between round steel and flat steel is 6 times the diameter of the round steel, double-sided welding; flat steel and steel pipe, The flat steel is welded to the angle steel , close to the outer sides of the angle steel, or close to the surface of the 3/4 steel pipe, and welded on the upper and lower sides; except for the welded joint buried in concrete, there are anti-corrosion measures.
Lightning protection down conductor
down conductor identification
Process description: Use the main reinforcement of the building column as the grounding down conductor. For each layer of the grounding down conductor, use yellow paint to paint a circle 0.3m above the ground of the down conductor steel bar, and the length of the painting 10cm.
Down conductor identification
Roof lightning protection strip
Process description: lightning protection wire should be laid horizontally or vertically, or can be laid parallel to the inclined structure of the building; the lightning protection wire should be straight and firm, and there should be no ups and downs and bends. , 100mm from the building surface. The distance between supporting parts should be 0.5~1.5m in the horizontal straight part; 1.5~3m in the vertical part; and 0.3~0.5m in the turning part. Hot-dip galvanizing will destroy the anti-corrosion protection during welding, and anti-corrosion treatment should be performed within 100mm of the weld mark. The lightning protection down conductor should be permanently marked with a metal nameplate.
The lightning protection belt passes through the expansion joint
The lightning protection belt is connected to the down conductor
The lightning protection belt is marked with the down conductor
Grounding resistance test point
Process description: Artificial grounding devices or grounding devices using building foundation steel bars must be placed above the ground. The design requires testing points to be set up at locations. The test point should form a disconnect card, and galvanized bolts should be used to fasten the connection to facilitate inspection and testing. The test point generally uses junction box . If the junction box is eliminated, the fixing parts of the hole cover should be pre-embedded in the cave wall, and the inner wall should be smoothed with cement mortar . The production of test points should be combined with the exterior decoration of the building to be practical and beautiful.
Ground resistance test point
Roof metal pipe grounding
Process description: The roof metal pipe must be grounded reliably and must not be directly welded. A grounding snap ring must be used and a copper core soft wire is used to connect to the grounding flat steel, and the anti-loosening parts are complete.
Roof metal pipe grounding
Roof metal components grounding
Process description: Other exposed metal components on the roof must be connected with lightning protection strips to form an integral electrical path. Each component must not be connected in series and must be individually connected to the grounded trunk line.
Metal stairs grounded
Metal components grounded
Roof casing grounded
Indoor metal doors and windows grounded
Process description: The second type of lightning protection building is when the building height exceeds 4 5m, larger railings, doors and windows on exterior walls of 45m and above should be Large metal objects are connected to the lightning protection device directly or through embedded parts.Category III lightning protection buildings When the building height exceeds 60m, larger metal objects such as railings, doors and windows on the exterior walls of 60m and above should be connected to the lightning protection device directly or through embedded parts. When grounding metal doors and windows, the connecting conductor should be laid concealed, and should be done after the window frame is positioned and before the construction of the wall decoration layer or the plastering layer.
Indoor metal doors and windows grounding
Lamp metal shell grounding
Process description: When the height of the lamp from the ground is less than 2.4m, the accessible exposed conductor of the lamp must be grounded (PE) or zeroed (PEN) reliably, and there should be a dedicated grounding bolt.
The metal shell of the lamp is grounded
Distribution box and metal conduit jumper
Process description: The metal frame and basic steel of the cabinet, screen, table, box, panel must be grounded (PE) or connected to zero (PEN) reliably; electrical appliances are installed The door can be opened, and the ground terminals and of the door and frame should be connected with bare braided copper wire and marked. A ground jumper must be made at the connection between the metal conduit and the distribution box, and each pipeline must be connected to the busbar or grounded trunk line separately and must not be connected in series.
Distribution box and metal conduit jumper
Distribution room door (frame) grounding
Process description: A ground jumper must be used between the door and the door frame of the distribution room and connected to the indoor ground trunk to form a good electrical path. . Braided copper wires should be used for grounding connections at the fence doors of the isolation and static compensation devices in the power distribution rooms and at the hinges of the metal doors in the power transformation and distribution rooms. The lightning arrester in the substation and distribution room should be connected to the ground trunk line with the shortest ground wire.
Power distribution room Door (frame) grounding
Electrical equipment grounding
Process description: The grounding of each electrical device should be connected with a separate grounding wire to the grounding bus or grounding trunk line. It is strictly forbidden to connect several in series in one wiring line. Electrical installations that require grounding. Important equipment and equipment structures should have two grounding down conductors connected to the main grounding grid at different locations. And each grounding down lead should meet the requirements of thermal stability and mechanical strength, and the connecting lead should be convenient for regular inspection and testing.
Electrical equipment grounding
Metal pipe jumper
Process description: Generally, there is no need to add jumper wires at the joints of metal pipes. However, jumpers must be added to the water meters of the water supply system and small sections of plastic pipes in metal pipes to ensure the effective equipotential bonding and grounding of the metal pipes.
Metal pipe jumper
Power distribution room grounding trunk
Process description: Installation requirements for exposed grounding trunks in the power distribution room: The grounding device is easy to inspect, and the laying position does not hinder the disassembly and maintenance of the equipment; when laying horizontally along the building wall, The height from the ground is 250~300mm; the gap between it and the building wall is 10~15mm; when the grounding wire crosses the building deformation joint, a compensation device is installed; the surface of the grounding wire is 15~100mm along the length direction, and each section is painted separately. With alternating yellow and green stripes; no less than 2 terminal posts or grounding bolts for temporary grounding should be installed on the grounding trunk lines of the transformer room and high-voltage distribution room. A rat-blocking board must be installed at the entrance of the power substation and distribution room, and the height of the rat-blocking board shall not be less than 60cm.
Distribution room grounding trunk
Distribution room grounding trunk
Distribution room mouse guard
Total equipotential bonding
Process description: Building equipotential bonding The trunk line should be from a ground with no less than 2 direct connections to the grounding device. The trunk lines or main equipotential boxes are drawn out, and the connecting lines between the equipotential bonding trunk lines or local equipotential boxes form a ring network. The ring network should be connected to the equipotential bonding trunk lines or local equipotential boxes nearby. Branch lines should not be connected in series.
Total equipotential bonding
Partial equipotential bonding
Process description: The equipotential bonding terminal board should be connected with bolts to facilitate disassembly and regular testing. After the equipotential bonding is installed, a continuity test should be carried out. The test power supply can be a DC or AC power supply with a no-load voltage of 4~24V. The test current should not be less than 0.2A. When the measured resistance between the equipotential bonding terminal board and the ends of metal pipes and other metal bodies within the equipotential bonding range does not exceed 3Ω, the equipotential bonding can be considered effective. If a pipe connection with poor conduction is found, jumper wires should be installed, and continuity tests should be performed regularly after being put into use.
local equipotential bonding
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