Key points and measures for supervision and contro

2022-09-27
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Key points and measures for supervision and control of lightning protection and grounding

(I) prior supervision and control of construction quality

1 Sampling inspection shall be carried out for materials entering the site according to the regulations, and the inspection conclusion shall be recorded, which can be applied in construction only if it meets the provisions of relevant technical standards

2. The installation of grounding device shall be carried out according to the following procedures:

(1) building foundation grounding body: after the laying of bottom plate reinforcement is completed, the grounding construction shall be carried out according to the design requirements. After inspection and confirmation, formwork erection and concrete pouring and tamping can be carried out

(2) artificial grounding body: excavate the trench according to the design position, and after inspection and confirmation, enter the grounding report to lay the underground grounding trunk line

(3) grounding module: excavate the module pit according to the design position, and lead the underground grounding trunk line to the module. After inspection and confirmation, they can be welded with each other

(4) device concealment: only after passing the inspection and acceptance can it be backfilled with earth

3. The installation of downlead shall be carried out according to the following procedures:

(1) use the main reinforcement in the building column as the downlead. After the main reinforcement in the column is bound, the construction shall be carried out according to the design requirements, and the formwork can be erected after inspection and confirmation

(2) lay the downlead buried in the painting layer directly from the foundation grounding body or artificial grounding body. After inspection, it is confirmed that it is not exposed, and then paste face bricks or paint

(3) lead out the exposed downlead directly from the foundation grounding or artificial grounding body, bury or install the support first, and lay the downlead after inspection and confirmation

4. Installation electricians, welders and electrical commissioning personnel shall work with certificates according to relevant requirements

5. All kinds of measuring instruments used for installation and commissioning shall be verified to be qualified and within the period of validity when used

(II) supervision control in construction quality matters

1 Operation conditions

(1) operation conditions of grounding body

① clear the site according to the design position

② the connection between bottom plate reinforcement and column reinforcement has been bound

③ the connection between reinforcement and column reinforcement in the column foundation has been bound

(2) working conditions of grounding trunk line

① the support is installed

② the protective pipe has been embedded

③ civil plastering is completed

(3) support installation conditions

① various supports have been transported to the site

② structural engineering has been completed

③ there must be scaffolding or ladders outdoors

(4) working conditions for concealed laying of lightning protection downlead

① buildings (or structures) have scaffolding or ladders, which can be operated by people

② when the main reinforcement is used as the downlead, the reinforcement is bound

(5) working conditions for open laying of lightning protection downlead

① the support installation is completed

② the building (or structure) has scaffolding or ladders, which can be operated by people

③ the external decoration of civil engineering is completed

(6) installation conditions of lightning strip and grading ring

when the reinforcement of civil ring beam is being bound, cooperate with this work

(7) lightning protection installation operating conditions

① the grounding body and downlead must be completed

② the bracket is installed

③ have the conditions of straightening site and vertical transportation

(8) working conditions for lightning rod installation

① the grounding body and downlead must be completed

② scaffold is required, and the scaffold is erected

③ the civil structure works have been completed, and the embedded parts have been completed with the structural construction

2. Construction process

(1) process flow support downlead exposed laying

grounding body grounding trunk lightning rod

downlead and enjoy independent intellectual property rights exposed laying

① the minimum size of artificial grounding body (pole) should comply with relevant regulations

② the buried depth of the grounding body should not be less than 0.6m at the top, and the angle steel and steel pipe grounding bodies should be configured vertically

③ the length of the vertical grounding body should not be less than 2.5m, and the spacing between them should generally not be less than 5m

④ the buried position of the grounding body should not be less than 1.5m from the building. When the grounding body is buried in garbage, ash, etc., the soil should be replaced and compacted in layers

⑤ when the grounding device must be buried less than 3m away from the entrance and exit of the building or the sidewalk, the grading tape method should be adopted or 50 ~ 90mm thick asphalt layer should be laid on the grounding device, and its width should exceed the grounding device by 2m

⑥ the connection of grounding body (wire) should be welded. The weld at the welding position should be full and have sufficient mechanical strength, and there should be no slag inclusion, undercut, cracks, false welding, pores and other defects. After the coating at the welding position is knocked clean, brush asphalt for anti-corrosion treatment

⑦ when lap welding is adopted, the welding length is as follows:

1) the galvanized flat steel shall not be less than 2 times its width, and welding shall be carried out on three sides (when the flat steel width is different, the lap length shall be subject to the width). Before laying, the flat steel should be straightened, and the bending should not be too dead. There should be no obvious bending on the straight section, and it should be placed vertically

2) the welding length of galvanized round steel is 6 times its diameter, and it shall be welded on both sides (when the diameters are different, the lap length shall be subject to the larger diameter)

3) when the galvanized round steel is connected with the galvanized flat steel, its length is 6 times the diameter of the round steel

4) when the galvanized flat steel is welded with the galvanized steel pipe (or angle steel), in order to connect reliably, in addition to welding on both sides of its contact part, the flat steel itself should be bent into an arc (or right angle) and welded with the steel pipe (or angle steel)

⑧ when the grounding wire meets the lime cinder layer and cannot be avoided, it shall be fully protected with cement slurry

⑨ when using chemical methods to reduce soil resistivity, the materials used should meet the following requirements:

1) weak corrosion to metals

2) low content of water-soluble components

⑩ all metal parts shall be galvanized. During operation, pay attention to protect the galvanized layer

(3) installation of artificial grounding body (pole)

① processing of grounding body

according to the quantity and material specification required by the design, the material is generally cut with round steel or angle steel, and the length should not be less than 2.5m. If steel pipes are used to drive underground, they should be processed into a certain shape according to the soil quality. In case of soft soil, they can be cut into an inclined plane. In order to avoid the pipe deflection caused by uneven stress during driving, it can also be processed into a flat pointed shape; When the soil is very hard, the tip can be processed into a cone. If angle steel is selected, an angle steel of no less than 40mm, 40mm and 4mm should be used, and the cutting length should not be less than 2.5m. One end of the angle steel should be processed into a pointed shape

according to the requirements of the design drawing, measure and snap the line to the line of the grounding body (), excavate a ditch with a depth of 0.8 ~ 1m and a width of 0.5m on this line, the upper part of the ditch is slightly wider, and the stones at the bottom should be removed

③ install grounding body (pole)

after the trench is excavated, install grounding body and radiant grounding flat steel immediately to prevent earthwork collapse. First place the grounding body on the center line of the ditch and drive it into the ground. Generally, hammer is used to drive it. One person holds the grounding body, and the other person hits the top of the grounding body with a sledgehammer. In order to prevent the grounding steel pipe or angle steel from being split, a protective pipe cap can be added to the end of the grounding pipe. The angle steel can be grounded by welding a short angle steel (about 1 cm) on the grounding angle steel. When hitting the grounding body with a hand hammer, it should be stable. The hammer should hit the center of the grounding body without deviation. It should be vertical to the ground. When the top of the grounding body is 600 mm away from the ground, stop driving

④ laying of flat steel between grounding bodies

flat steel should be straightened before laying, and then the flat steel should be placed in the ditch, and the flat steel should be welded with the grounding body by electricity (gas welding) in turn. Flat steel should be placed on the side rather than flat, and the dissipation resistance is small when placed on the side. The connection between flat steel and steel pipe is about 100 mm away from the highest point of the grounding body. During welding, the flat steel shall be straightened, the coating shall be removed after welding, the asphalt shall be brushed for anti-corrosion treatment, and the grounding wire shall be led out to the required position, with sufficient connection length reserved for use

⑤ check the grounding body (wire)

after the grounding body is connected, the quality inspection department should be asked to carry out hidden inspection in time. The material, position, welding quality and Section specification of the grounding body (wire) all meet the requirements of the design and the current national relevant technical specifications. Backfilling and layered compaction can be carried out only after the inspection is qualified. Finally, fill in the telemetry value of grounding resistance on the hidden inspection record

(4) natural foundation grounding body installation

① use non waterproof bottom plate reinforcement or deep foundation grounding body

use the non waterproof bottom plate reinforcement or deep foundation as the grounding body, mark the position according to the size and position requirements of the design drawing, lap weld the bottom plate reinforcement, and weld the main reinforcement below the outdoor ground. Then lap weld the bottom of the main reinforcement of the column (no less than 2) and the reinforcement of the bottom plate, weld the connecting plate of the main reinforcement below the outdoor ground, remove the coating, and mark the two main reinforcements with color paint for easy extraction and inspection. The quality inspection department should be invited to carry out hidden inspection in time, and make hidden inspection records at the same time

② use the pile foundation and cushion cap reinforcement to make the grounding body, find the number and position of pile foundation groups according to the size and position of the design drawing, lap and seal the four corner reinforcement of each pile foundation, and then weld it with a box of tofu and a bag column main reinforcement (no less than 2), and under the outdoor ground, embed the main reinforcement with the grounding connecting plate, remove the coating, and mark the two main reinforcements with color paint for easy extraction and inspection, and timely ask the quality inspection department for hidden inspection, At the same time, make hidden inspection records

(5) installation of grounding main line

① when the grounding main line passes through the wall, it should be protected by casing, and when crossing the expansion joint, it should be compensated by bending

② the grounding main line should be equipped with a disconnecting clip prepared for measuring the grounding resistance, which is generally installed in a cassette, and at the same time, the box cover should be added and the grounding mark should be made

③ when the grounding main line crosses the door, it should be concealed in the ground (buried before making the ground)

④ the distance between the grounding main line and the ground shall not be less than 200 mm, and the distance between the grounding main line and the wall surface shall not be less than 10 mm. The support shall be 40 mm 4mm Flat steel, and the tail end shall be made into dovetail shape. The depth and width of the hole are 50mm respectively, and the total length is 70mm. The horizontal straight-line distance between supports is generally 1m, the vertical part is 1.5m, and the turning part is 0.5m

⑤ the laying of grounding trunk line shall be straight, and the allowable deviation between levelness and verticality shall be 2/1000, but the total length shall not exceed 10mm

⑥ the bending radius of the grounding main line at the corner shall not be less than 2 times the thickness of the flat steel

⑦ the grounding main line should be painted with black paint, which should be uniform without omission, but the disconnection clip and grounding terminal should not be painted

(6) installation of grounding main line

the grounding main line should be connected with the flat steel connected to the grounding body, which is divided into indoor and outdoor connections. The outdoor grounding main line and branch line are generally laid in the trench. Indoor grounding trunk lines are mostly laid in the open, but the branch lines connected to some equipment need to pass through the ground, and can also be buried in concrete. The specific installation methods are as follows:

① laying of outdoor grounding trunk line

1) first, straighten, measure the position, drill holes, simmer and bend the grounding trunk line, and install the disconnection clip and grounding terminal

2) before laying, dig ditches according to the size and position required by the design. See the same above for trenching requirements, and then place the flat steel flat and bury it. The backfill shall be compacted, and the end of the grounding trunk line shall be no more than 0.5m above the ground for grounding

② open laying of indoor grounding trunk line

1) reserved holes and embedded supports

according to the size and location of the design requirements, reserved holes for grounding wires shall be reserved, and the size of the reserved holes shall be more than 6mm larger than the thickness and width of the laying grounding trunk line. There are three methods:

a: during construction, a section of flat steel can be cut according to the above requirements and embedded in the wall. When the concrete has not yet solidified, the flat steel can be pumped so that it can be easily extracted after solidification

b: wrap a layer of linoleum or several layers of kraft paper on the flat steel and bury it in the wall, and reserve the hole spacing

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