Lightning detection is a fundamental aspect of lightning protection technology services. Determining whether a building's lightning protection device is qualified and effective largely depends on the correctness of the detection method used and the reliability of the detection data. This requires that the detection method must be correct and the detection data must be reliable. Only in this way can we establish the professionalism and authority of lightning protection testing work

2. Building lightning protection detection technology and methods

1. Lightning arrester detection

The types of lightning arrester include needle, belt, net, wire, metal, etc.

. Firstly, calculate the protection range of the lightning arrester (1) Use the rolling ball method to calculate the protection range of lightning rods and lightning wires, and pay attention to the impact (2) Use the grid method to determine the protection range of the lightning strip and network, and check its grid size, laying method, connection between the lightning strip and the down lead, and whether the path is closed (3) For non-metallic objects protruding from the roof at the top of a building, as well as related spaces outside the vent pipes, breathing valves, exhaust ducts, etc. that emit explosive hazardous gases, vapors, or dust, it is also necessary to check whether they are within the protection range of lightning protection devices. Secondly, check the height, material specifications, installation position (whether lightning prone parts are installed), anti-corrosion measures, connection form and quality of the lightning arrester. In addition, it is necessary to check whether the lightning arrester at the top of the building, other exposed metal objects at the top of the building, and the down lead are electrically connected; Check if there are any other electrical circuits attached to the lightning arrester; Check whether the distance between the overhead lightning protection line, network, and the protected object meets the requirements

2. Ground resistance detection

(1) Voltammetry detection. When measuring resistance, it is necessary to first estimate the magnitude of the current and select an appropriate cross-section of the insulated wire. During the preparation test, the variable resistor r can be used to adjust the current. When officially measured, the variable resistor is short-circuited, and the grounding resistance can be calculated from the values obtained from the ammeter and voltmeter. The voltammetry method has obvious shortcomings in measuring ground resistance. During the test, the distance between the grounding rod and the ground electrode is 20-50m, while the auxiliary grounding is 40-100m from the ground point. In addition, it is greatly affected by external interference and sometimes cannot be measured in high voltage areas (2) Measurement instrument detection method. The single jaw grounding resistance tester is currently a popular type of grounding resistance tester. Due to its compact size and easy operation, the instrument is an ideal instrument for detecting the quality of grounding devices. This instrument is suitable for measuring the grounding resistance of grounding devices such as output wire towers, microwave towers, lightning rods, etc. Although the single jaw grounding resistance tester uses a certain frequency signal to eliminate interference during testing, it can also be interfered with when there is a large current on the tested cable, resulting in inaccurate results and inability to measure soil resistivity. The double clamp method also has the same problem, so it is recommended to use the ground pile auxiliary method for measurement in cases of strong external interference. For large-scale system grounding, network grounding, soil resistivity testing, and auxiliary devices with good grounding conditions, ground pile auxiliary grounding resistance tester should also be selected. This instrument can effectively ensure the repeatability and stability of ground resistance measurement values

3. Downlead detection

First, check the number of downleads and use a clamp resistance tester to test for continuity.

. Calculate whether the spacing is qualified, whether the layout is uniform, and whether there are down conductors installed at edges, corners, and turns; Whether two main bars are selected for the down lead of the column reinforcement. Note that for the third type of building, when only the steel columns or column steel bars around the building are used as down conductors, down conductors can be set according to the span, and the average spacing between down conductors should not exceed 25m. For the exposed down lead, measure its material specifications, construction process, including connection form and quality, anti-corrosion status, etc; Concealed down conductors shall be traced and detected based on concealed engineering records. Additionally, check for any other electrical circuits attached to the down lead. The testing of the down lead resistance test terminal can be carried out by measuring one measurement point for each down lead to test its grounding resistance value. For exposed down conductors (not individual) with disconnect cards, their connections should be disconnected for testing

4. Detection of side lightning protection measures

Detection of the height and distance between the first equalizing ring in high-rise buildings, the material specifications and laying methods of the equalizing ring, the connection status between large metal objects such as railings and doors and windows on the exterior wall and lightning protection devices, anti-corrosion measures, connection forms and quality (check the tracking and detection of hidden engineering records).

. Measure the grounding resistance value of larger metal objects or the transition resistance value with lightning protection devices using testing instruments. The measurement method can be based on two measuring points for each independent equalizing ring meter; Metal doors, windows, railings, and other external wall metal objects, as well as their reserved grounding, are measured at 1 point every 2; Glass curtain wall every 10m × One measuring point per 10m

5. Detection of Lightning Protection and Electric Intrusion in Metal Pipelines

Measures for Lightning Protection and Electric Wave Intrusion in Overhead or Buried Metal Pipelines:

(1) Category 1 Lightning Protection Building Detection: Check whether the overhead metal pipeline is connected to the grounding device of lightning protection induction at the entrance and exit of the building.

. Is the pipeline within 100m of the building grounded every 25m or so; Metal pipelines buried or in trenches shall be tested for connection to lightning protection induction grounding devices at the entrance and exit of buildings (2) For Class II and Class III lightning protection buildings, check whether overhead or buried metal pipelines are connected to the lightning protection grounding device nearby or directly grounded at the entrance and exit of the building. The second type of lightning protection building also requires testing whether the overhead metal pipeline is grounded once at a distance of about 25m from the building. Inspect the materials and specifications of the relevant connections and grounding conductors, and further check the connection quality. The grounding resistance value of metal water pipes, metal gas pipes, and other metal pipelines can be measured at one measuring point at the entrance of each grounding point into the building, and their equipotential connection transition resistance can be tested