The important equipment and equipment frame shall have two grounding down leads connected to different places of the main grounding grid.
The connection between the metal conduit and the distribution box must be grounded and bridged, and each pipeline must be connected to the busbar or the grounding main line separately, not connected in series.
This paper explains 15 process nodes of lightning protection and grounding construction in detail, with examples of excellent project pictures for reference and reference to guide construction or inspection.
01 Lightning protection downlead process description: the grounding device shall be welded by lap welding, and the lap length shall comply with the following provisions: the lap length between flat steel and flat steel shall be twice the width of flat steel, and shall not be less than three sides of welding; The lap joint between round steel and round steel shall be 6 times of the diameter of round steel and shall be welded on both sides; The lap joint between round steel and flat steel shall be 6 times of the diameter of round steel, and shall be welded on both sides; Flat steel shall be welded with steel pipe, flat steel shall be welded with angle steel, close to the two sides outside the angle steel, or close to the surface of 3/4 steel pipe, and the upper and lower sides shall be welded; In addition to the welded joints buried in concrete, anti-corrosion measures shall be taken.
When the metal doors and windows are grounded, the connecting conductors should be laid in a concealed manner, and should be carried out after the window frame is positioned and before the construction of the wall decorative layer or plastering layer.
Because of its strong specialty and many concealed works, it is often a difficult point in building engineering.
The grounding connection at the fence door of the power distribution room isolation and static compensation device and the hinge of the metal door of the power transformation and distribution room shall adopt braided copper wire.
It is strictly prohibited to connect several electrical devices that need to be grounded in series in one grounding wire.
For the third type of lightning protection building, when the building height exceeds 60m, large metal objects such as railings, doors and windows on 60m and above external walls shall be connected to the lightning protection device directly or through embedded parts.
The lightning strip is connected with the downlead through the expansion joint.
Metal nameplates shall be used to make permanent marks at lightning protection downlead.
The fabrication of test points shall be combined with the external decoration of buildings to achieve practical and beautiful appearance.
Grounding of indoor metal doors and windows 08 Grounding process description of metal shell of lamps: when the height of lamps from the ground is less than 2.4m, the accessible bare conductors of lamps must be reliably grounded (PE) or connected to neutral (PEN), and there should be special grounding bolts.
The distance between supports should be 0.5~1.5m in the horizontal straight line; The vertical part should be 1.5~3m;; The turning part should be 0.3-0.5m.
However, jumper wires shall be added to the water meter of the water supply system and small plastic pipes in the metal pipes to ensure the effective equipotential bonding and grounding of the metal pipes..
Grounding resistance test point 05: roof metal pipe grounding process description: roof metal pipe must be reliably grounded, and must not be directly welded.
It must use grounding snap ring and copper core flexible wire to connect with grounding flat steel, and the anti loose parts are complete.
Each grounding down lead shall meet the requirements of thermal stability and mechanical strength, and the connecting lead shall be convenient for regular inspection and test.
If the junction box is cancelled, the fixing parts of the hole cover shall be embedded on the hole wall, and the inner wall shall be plastered with cement mortar.
Description of identification process of lightning protection downlead 02: each layer of the main reinforcement of the building column as the grounding downlead shall be painted with a circle of yellow paint 0.3m above the ground, with a length of 10cm.
Jumping process description of electrical equipment grounding 12 metal pipe: generally, jumper wire is not required at the connection of metal pipe.
Lightning protection and grounding is an important sub project in building electrical engineering.
Grounding of metal shell of lamp 09 Process description of jumper between distribution box and metal conduit: the metal frame and basic profile steel of cabinet, screen, console, box and panel must be grounded (PE) or connected to neutral (PEN) reliably; The openable door with electrical appliances shall be connected with the grounding terminal of the frame with bare braided copper wire and marked.
Each component shall not be connected in series and must be connected to the grounding main line separately.
The welding of hot-dip galvanized steel will damage the hot-dip galvanized anti-corrosion, and anti-corrosion treatment shall be carried out within 100mm of the welding mark.
Grounding of metal stairs, grounding of metal components, grounding of roof bushings, 07 Grounding process of indoor metal doors and windows: when the height of the second type lightning protection building exceeds 45m, large metal objects such as railings, doors and windows on the 45m and above exterior walls should be connected to the lightning protection device directly or through embedded parts.
The downlead on the lightning strip is marked with 04.
Door (frame) grounding of power distribution room 11 Grounding process description of electrical equipment: the grounding of each electrical device shall be connected to the grounding bus bar or grounding trunk with a separate grounding wire.
The lightning arrester in the power transformation and distribution room shall be connected to the grounding main line with the shortest grounding wire.
The test points shall form a disconnection card, which shall be fastened with galvanized bolts to facilitate inspection and testing.
Distribution box and metal conduit jumper 10 Grounding process of distribution room door (frame): grounding jumper must be used between the door and the door frame of the transformation and distribution room, and connected with the indoor grounding trunk line to form a good electrical path.
The process description of the grounding resistance test point: the manual grounding device or the grounding device using the building foundation reinforcement must be set with test points above the ground according to the design requirements.
The junction box is generally used at the test point.
Downlead identification 03 Roof lightning strip process description: the lightning conductor shall be laid horizontally or vertically, or parallel to the inclined structure of the building; The lightning conductor shall be straight and firm, free from ups and downs and bending, and 100mm from the building surface.
Roof metal pipe grounding 06 Roof metal component grounding process description: other exposed metal components of the roof must be connected with the lightning strip to form an integral electrical path.
