Detection of lightning protection devices in buildings?

it is very important to detect the lightning protection device of buildings, and it is essential to prevent lightning in rainy days. Although the probability is small, it is possible to do a good job of protection, and every detail is crucial. Zhongda Consulting will explain to you the detection of lightning protection devices in buildings.

1. Detection object and detection part

1.1 Check the materials, specifications, anti-corrosion measures and corrosion of the lightning arrester on site to see whether the installation is vertical, whether the welding is firm, and whether there is any breakage or melting. Check whether the connection between the lightning arrester and the down lead is reliable and the shunt situation. For single or multiple lightning rods, the rolling ball method is used to determine the protection scope and whether it can protect buildings.

1.1.1 lightning arrester for buildings and other buildings, the diameter of round steel should be greater than or equal to 8mm, the cross-sectional area of flat steel should be greater than or equal to 48 mm ㎡, and the thickness should be greater than or equal to 4 mm. When conducting on-site inspection, use a hammer or pliers to knock the net belt properly. Check whether there are unreasonable places such as opening welding and bending at right angles or less.

1.1.2 The lightning arrester of water tower requires the use of iron fence around the top of water tower to protect the lightning arrester or lay the edge of annular lightning protection belt, and a lightning rod is installed in the center of the tower top. You can observe the condition of the lightning receptor through a high-powered telescope.

1.1.3 the chimney lightning arrester is protected by lightning rods or annular lightning strips installed at the top of the chimney, and multiple lightning rods are connected into a closed loop by lightning strips.

1.2 on-site check whether the down lead is vertical and firm, and whether it follows the shortest path principle; Check whether the diameter and cross-sectional area of down lead material meet the specified requirements; Whether the layout of down lead is reasonable or not, protective measures should be taken according to the distance between the entrance and exit of the building and the sidewalk, and the distance must be greater than or equal to 3.m；; Check whether the disconnected card is rusted and has poor contact. It is advisable to set a disconnection card at a distance of 1.8m from the ground; Check whether nonmetallic protective casing is set below 1.5m from the ground; Check whether the down lead is deformed and whether there is a right angle or an acute angle bend at the blue bend; Check whether there is fracture, mechanical damage, serious corrosion, etc., and replace it when the section corrosion is greater than or equal to t/3; Check whether the down lead is firmly and reliably welded with the lightning receptor and grounding device, and whether there are cracks in the solder joints, etc. The layout of down lead should include: whether lightning counterattack and lightning electromagnetic pulse interference can be caused, whether there are other equipment leads nearby, whether there are cross or parallel electrical lines, and if so, measures should be taken; Whether the overvoltage of down lead meets the requirements, whether it passes through temporary buildings and whether it is easy to check. For a water tower with a height less than or equal to 4.m, the iron ladder can be used as the down lead; When the height is greater than 4.m, another down lead should be added or the main reinforcement in the pillar should be used as the down lead. For chimneys with a height less than or equal to 4.m, iron escalators can be used as downlead; When the height is greater than 4.m, an additional down lead shall be installed or the main reinforcement in the pillar or bearing shall be used as the down lead.

1.3 the detection of grounding device is mainly marked by the actual measurement of grounding power frequency resistance value. Grounding device mainly checks the installation location, depth, specifications, anti-corrosion, impact grounding resistance, etc., and checks whether the grounding device materials, specifications, layout, etc. in the lightning protection design drawings in the infrastructure files are designed reasonably.

for structures such as water towers and chimneys. Because its lightning protection devices are exposed to the outside, the lightning rod and down lead can usually be observed on the spot through high-powered telescope, and hidden dangers can be found in time. When necessary, the inspector should climb to the highest place for on-the-spot inspection and measurement.

during detection, several points should be selected for measurement, and finally the grounding resistance value of this point should be determined by averaging. If all the tested power frequency grounding resistances are qualified, it is unnecessary to test the soil resistivity and calculate the impact resistance.

2. Preparation before inspection and inspection procedures

2.1 Preparation before inspection

2.1.1 The inspection plan shall be formulated by the person in charge of on-site inspection technology, and shall be notified to the construction party and the project owner in writing. When the construction reaches those parts and links, the construction party must notify the inspection station to conduct inspection in time and make original records;

2.1.2 The person in charge of familiarizing with the technology of the project shall organize the relevant testing personnel to familiarize themselves with the technical description of the testing project. This part is the key point of familiarity and a detailed work. The testing personnel must understand the mandatory index requirements of the relevant national standards for each testing project.

2.1.3 The civil construction party is responsible for the construction of the lightning protection device of the project. According to the principles of honesty, trustworthiness and law-abiding, and according to the testing agreement, the testing unit specifically implements the duties of the testing personnel to ensure the integrity of the whole testing process and testing data, and the lightning protection device meets the technical requirements of national standards.

2.1.4 test record form preparation related test record form preparation, according to the specific situation of new buildings, prepare a set of complete test forms from the beginning of foundation test to the completion of the project, and designate special personnel to keep them.

2.2 detection procedure

2.2.1 in the preliminary preparation stage, ① accept the detection task to understand the situation of the inspected unit. This is a necessary preparatory work, which paves the way for the following work, such as making a testing plan, signing an agreement, testing implementation, etc. At least we should know its general situation, such as specific address, scale, nature, soil type, testing site environment, etc. (2) develop a testing scheme. The plan should be as detailed as possible. ③ Sign a testing agreement or contract, or in the form of a power of attorney. ④ Staffing. According to the nature and industry characteristics of the inspected unit, it is equipped with testing technicians with corresponding professional expertise. ⑤ Master relevant knowledge. Understand and master the professional knowledge and relevant norms and regulations related to the inspected unit, including national standards, industry norms, local standards and relevant safety procedures and operating procedures. ⑥ Prepare the instrument. Different equipment and facilities need different testing equipment. According to the testing object, prepare and check the main and standby testing instruments and equipment to ensure that they can be used normally within the valid use period after verification.

2.2.2 arrive at the inspected unit in the on-site inspection stage ①, and take the initiative to show relevant certificates to the inspected unit. (2) refer to the lightning protection engineering technical data and drawings of this test object, understand and record the importance, use nature and possible consequences of lightning accidents of the tested monomer, and determine its lightning protection category, lightning protection zone division and items to be tested. (3) patrol the tested monomer and the surrounding environment, reasonably arrange the auxiliary pile position of grounding resistance tester and connect wires according to the testing principle and requirements of the instruments used, check the instruments and equipment again, and record the model name and testing auxiliary pile position of grounding resistance tester. ④ Conduct on-site inspection and record data. According to the determined detection items, in the order that external lightning protection devices are detected first, then internal lightning protection devices are detected, inspectors will patrol and inspect the visual quality of lightning protection devices of buildings (structures) and facilities, and measure the relevant technical parameters. At the same time, they will sample the grounding resistance or transition resistance test points and draw the plane schematic diagram of the test points. After marking and numbering the test points, they will measure the grounding resistance and transition resistance, and the measurement results-readings will be recorded in the corresponding original record table as required. ⑤ Review, confirm and sign. After the on-site inspection is completed, the instruments and equipment shall be inspected again to confirm that they are normal, and the original records shall be checked and rechecked by the test sampler, tester and recorder, and then signed at the designated main inspection and rechecking office. At the same time, the defects of lightning protection devices found on the spot and confirmed by on-site inspection are summarized to form a notice of problems and submit it to the on-site person in charge of the inspected unit, who will confirm the test results and sign at the designated place.

2.2.3 analysis and processing stage ① collate test data and issue relevant test documents. After calculating, sorting and processing the data in the original record table, judge according to the corresponding technical standards, compile and issue a notice of existing problems for the newly determined problems; Issue inspection reports for regular inspection or completion inspection; For the re-inspection after rectification, prepare and issue a re-inspection opinion. (2) review, issue and seal the relevant testing documents. ③ Register and send relevant testing documents, and establish files.

2.2.4 service evaluation and follow-up visit ① when the inspected unit receives the test report and other documents, please fill in the lightning protection testing work style and service quality evaluation form, recover the evaluation form and establish account files. (2) The management personnel of testing institutions shall follow up and pay a return visit to the testing activities at a rate of not less than 3% by telephone or on-site understanding or invitation to hold a forum.

3. detection methods and precautions

detection methods include consulting data, checking visual quality, measuring technical parameters and analyzing and processing.

3.1 consulting materials refers to consulting design drawings, concealed works records, as-built drawings and other related materials.

3.2 checking visual quality refers to the process of checking the visual quality of exposed parts of various lightning protection devices and measures, and recording and judging whether they meet the requirements.

3.3 measuring technical parameters refers to measuring, reading and recording various technical parameters of lightning protection devices by using various instruments and instruments.

3.4 analysis refers to the process of calculating, analyzing and processing the measured data of various technical parameters and judging whether they meet the requirements.

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