Construction Points of Lightning Protection and Grounding for High-Frequency UPS

New Idea Electric Co.,Ltd.

Addtime: 2026-02-25 Clicknum

Construction Points of Lightning Protection and Grounding for High-Frequency UPS

As the core equipment to ensure the stable power supply of key electrical systems, high-frequency Uninterruptible Power Supply (UPS) is widely used in data centers, industrial control rooms, medical institutions, financial institutions and other scenarios that have strict requirements on power supply reliability. Due to the high integration of internal electronic components, narrow safety margin of voltage resistance, and sensitive response to transient overvoltage, high-frequency UPS is more vulnerable to lightning strikes and electromagnetic interference than traditional UPS. The lightning protection and grounding system is the first line of defense to protect high-frequency UPS from lightning damage, and its construction quality directly determines the anti-lightning performance of the UPS system, the safety of equipment operation, and even the personal safety of operators. To ensure that the lightning protection and grounding system can effectively divert lightning current, suppress transient overvoltage, and avoid hidden dangers such as ground potential counterattack and equipment burnout, the construction must strictly abide by relevant international and national standards, follow the principles of "hierarchical protection, unified grounding, and standardized wiring", and focus on controlling every key link of construction. This article details the core construction points of lightning protection and grounding for high-frequency UPS, providing a professional and standardized guide for on-site construction.

I. Key Points of Pre-Construction Preparation

Pre-construction preparation is the foundation to ensure the quality of lightning protection and grounding construction. It is necessary to combine the technical parameters of high-frequency UPS equipment, on-site environmental conditions, and relevant standard requirements to complete the design, on-site investigation, material preparation and technical disclosure, so as to avoid rework, hidden dangers and safety accidents during the construction process.

1. Standardized Design and Scheme Review

Before construction, a special lightning protection and grounding construction scheme must be compiled in accordance with international standards such as IEC 62305 (Lightning Protection of Structures and Electronic Systems), national standards such as GB 50057-2010 Code for Design of Lightning Protection of Buildings, GB 50054-2011 Code for Design of Low-Voltage Distribution Systems, and the technical requirements of high-frequency UPS equipment manufacturers. The scheme must clearly define the following core contents to ensure scientificity and operability:

Lightning protection level: Determine the lightning protection level of the UPS room and the system according to the on-site lightning activity frequency, the importance of the UPS system, and the value of the protected equipment. Generally, high-frequency UPS systems in key scenarios (such as data centers) are designed according to Lightning Protection Level II or above.
Grounding resistance limit: The grounding resistance of the high-frequency UPS system is strictly required to ensure the effective diversion of lightning current. Under normal circumstances, the comprehensive grounding resistance shall not be greater than 4Ω; in areas with high soil resistivity (such as desert areas) or multi-thunderstorm areas, the grounding resistance shall be controlled within 1Ω to avoid poor grounding leading to lightning current accumulation and equipment damage.
Layout of grounding electrodes: Clarify the type, material, layout density and burial depth of grounding electrodes (vertical grounding electrodes and horizontal grounding electrodes). According to the on-site soil conditions, determine whether to adopt enhanced grounding measures such as soil replacement, resistance reducing agent or grounding module.
Layout of down conductors: Determine the number, material, cross-sectional area and routing of down conductors, ensuring that the down conductors are as short and straight as possible to reduce the impedance of lightning current diversion and avoid sharp bends and long-distance detours.
Selection and installation of lightning protection devices: Select surge protectors (SPD) that match the technical parameters of high-frequency UPS. The input and output ends of UPS, as well as the signal lines (such as communication lines and monitoring lines) must be equipped with corresponding SPDs. The model, rated voltage, discharge current and response time of SPD must be compatible with the UPS equipment to avoid SPD failure affecting the normal operation of UPS.

After the compilation of the construction scheme, it must be reviewed by professional technical personnel, equipment manufacturers and relevant supervision departments. Only after the review is passed can the construction be started. At the same time, it is necessary to check the input and output voltage, rated power, anti-surge capacity and other parameters of the high-frequency UPS to ensure that the lightning protection and grounding system is fully matched with the equipment.

2. On-Site Investigation and Soil Treatment

On-site investigation is the key to formulating a reasonable grounding scheme. Before construction, it is necessary to conduct a detailed investigation of the construction site, focusing on the following aspects:

Detection of soil resistivity: Use a soil resistivity tester to detect the soil resistivity of the grounding electrode layout area. The detection points shall be evenly distributed, and the detection depth shall not be less than the burial depth of the grounding electrode (generally 0.8-1.2m). According to the detection results, judge the difficulty of grounding construction and select the appropriate grounding mode. If the soil resistivity is too high (greater than 1000Ω·m), it is necessary to take enhanced grounding measures in advance.
Investigation of underground facilities: Investigate the distribution of underground pipelines (power cables, communication cables, water supply and drainage pipelines), underground structures, and other hidden dangers in the construction area. Mark the avoidance area clearly to prevent damage to underground facilities during the excavation of grounding trenches, which may lead to safety accidents or equipment failure.
Investigation of on-site environment: Observe the surrounding environment of the UPS room, such as whether there are tall buildings, trees, power lines and other objects that may affect the lightning protection effect. Avoid arranging grounding electrodes and down conductors in areas prone to water accumulation, corrosion or mechanical damage.

For areas with high soil resistivity, soil treatment shall be carried out in advance to reduce the grounding resistance. Common treatment measures include:

Soil replacement: Replace the soil in the grounding electrode area with soil with low resistivity (such as fine sand, clay, loam, etc.), and the replacement thickness shall not be less than 0.5m to ensure that the grounding electrode is fully in contact with the low-resistivity soil.
Adding resistance reducing agent: Use environment-friendly and long-acting resistance reducing agent (such as bentonite resistance reducing agent, graphite resistance reducing agent, etc.), which is evenly covered around the grounding electrode. The resistance reducing agent must be non-corrosive to the grounding electrode material, and its service life shall be consistent with the service life of the grounding system (not less than 20 years).
Installing grounding modules: For areas with extremely high soil resistivity, install metal grounding modules (such as copper-clad steel grounding modules, graphite grounding modules) to increase the contact area between the grounding electrode and the soil and improve the grounding effect. The grounding modules shall be buried vertically, and the distance between adjacent modules shall not be less than 5m to avoid mutual interference.

3. Material Selection and Inspection

The quality of lightning protection and grounding materials directly affects the service life and reliability of the system. All materials must comply with relevant national standards and design requirements, and priority shall be given to materials with good conductivity, corrosion resistance and durability. The key materials and their selection requirements are as follows:

Grounding electrodes and down conductors: Priority shall be given to hot-dip galvanized steel materials (hot-dip galvanized angle steel, hot-dip galvanized flat steel, hot-dip galvanized round steel) or copper materials (copper flat bar, copper round bar). For high-frequency UPS systems, hot-dip galvanized flat steel is preferred because of its good conductivity, corrosion resistance and convenient installation. The thickness of hot-dip galvanized flat steel shall not be less than 4mm, and the width shall not be less than 40mm; the cross-sectional area of hot-dip galvanized round steel shall not be less than 16mm²; the cross-sectional area of down conductors shall not be less than 25mm² to ensure that it can bear the impact of lightning current.
Surge Protector (SPD): It must be a product that has passed national certification (such as CCC certification) and meets the technical requirements of high-frequency UPS. The input and output ends of UPS shall be equipped with Class II SPD (Type 2 SPD) with a discharge current of not less than 20kA (8/20μs); the signal lines shall be equipped with signal SPD matching the signal type (such as RS485 signal SPD, Ethernet signal SPD) to avoid transient overvoltage damaging the internal electronic components of UPS.
Connecting parts: The connecting parts (such as bolts, nuts, welding materials) shall be made of the same material as the grounding electrodes and down conductors, or materials with better corrosion resistance. For example, hot-dip galvanized connecting parts shall be used for hot-dip galvanized steel materials, and copper connecting parts shall be used for copper materials. Welding materials shall be high-quality welding rods to ensure the firmness and conductivity of the connection.
Resistance reducing agent and grounding module: The resistance reducing agent shall be environment-friendly, non-toxic and non-corrosive, and its resistivity shall be less than 10Ω·m; the grounding module shall have stable performance, and its compressive strength shall not be less than 10MPa to avoid damage during burial.

Before entering the site, all materials must be inspected for quality. Check the product certificate, inspection report, and appearance quality (such as whether the hot-dip galvanized layer is uniform, whether there is peeling, corrosion, or damage; whether the SPD is intact, whether the parameters are consistent with the design requirements). Materials that do not meet the requirements shall not be used for construction to avoid hidden dangers.

II. Key Points of On-Site Construction

On-site construction is the core link to ensure the quality of lightning protection and grounding. It is necessary to strictly follow the construction scheme and relevant operation specifications, focus on controlling the construction quality of grounding electrodes, down conductors, connections, SPD installation and other links, and ensure that every construction step meets the requirements.

1. Construction of Grounding Electrode System

The grounding electrode system is the foundation of the lightning protection and grounding system, responsible for diverting lightning current to the ground and maintaining the stability of the ground potential. The construction shall be carried out in accordance with the following requirements:

Excavation of grounding trench: The grounding trench shall be excavated according to the designed layout, with a depth of 0.8-1.2m and a width of 0.3-0.5m. The trench shall be kept flat and free of sharp stones, debris and other objects that may damage the grounding electrode. In areas with high groundwater level or prone to water accumulation, the burial depth of the grounding electrode shall be appropriately increased to avoid the grounding electrode being corroded by water immersion for a long time.
Installation of vertical grounding electrodes: Vertical grounding electrodes (hot-dip galvanized angle steel or round steel) shall be buried vertically at the bottom of the grounding trench, with a burial depth of not less than 2.5m. The top of the vertical grounding electrode shall be 0.8-1.0m below the ground surface to avoid being damaged by external forces. The distance between adjacent vertical grounding electrodes shall not be less than 5m (if grounding modules are used, the distance shall be not less than 3 times the length of the module) to ensure that there is no mutual interference between the grounding electrodes and the grounding resistance can be effectively reduced.
Installation of horizontal grounding electrodes: Horizontal grounding electrodes (hot-dip galvanized flat steel) shall be laid horizontally at the bottom of the grounding trench, and connected firmly with vertical grounding electrodes. The horizontal grounding electrode shall be in close contact with the soil, and the laying shall be straight as far as possible, avoiding sharp bends. The distance between adjacent horizontal grounding electrodes shall be 2-3m to form a uniform grounding network.
Backfilling of grounding trench: After the installation of the grounding electrode is completed, backfill the grounding trench with the original soil or replaced low-resistivity soil, and tamp it layer by layer. The backfill soil shall be free of stones, debris and corrosive substances. If resistance reducing agent is used, it shall be evenly spread around the grounding electrode before backfilling, with a thickness of not less than 10cm, ensuring that the grounding electrode is fully wrapped by the resistance reducing agent.

2. Construction of Down Conductor System

The down conductor is responsible for connecting the lightning receptor (such as lightning rod, lightning strip) and the grounding electrode system, and diverting the lightning current to the ground quickly. The construction shall focus on ensuring the conductivity, firmness and short path of the down conductor:

Routing of down conductors: The down conductor shall be routed as short and straight as possible, avoiding long-distance detours and sharp bends (the bending radius shall not be less than 10 times the diameter of the down conductor). The down conductor shall be installed on the outer wall of the building or along the structural column, and shall be kept away from the input and output cables of the UPS, signal lines and other sensitive lines to avoid electromagnetic interference caused by lightning current.
Fixing of down conductors: The down conductor shall be fixed firmly with fixing brackets, and the spacing of the fixing brackets shall be 1.5-2.0m. The fixing brackets shall be made of hot-dip galvanized steel materials, and the connection between the brackets and the down conductor shall be tight to avoid loosening. The down conductor shall be kept vertical, and the deviation shall not exceed 3mm per meter.
Connection of down conductors: The connection between the down conductor and the lightning receptor, and between the down conductor and the grounding electrode shall be firm and reliable, and welding connection shall be preferred. The length of the welding seam shall not be less than 2 times the width of the flat steel or 6 times the diameter of the round steel, and the welding shall be full, free of pores, cracks and slag inclusion. If bolt connection is used (only for temporary connection or special occasions), the connecting surface shall be treated with derusting and anti-corrosion, and a spring washer shall be added to ensure tight connection and good conductivity.
Anti-corrosion treatment of down conductors: For down conductors installed outdoors, anti-corrosion treatment shall be carried out on the surface. Hot-dip galvanized down conductors shall be inspected for the integrity of the galvanized layer; if there is damage, zinc-rich paint shall be applied for repair. For down conductors passing through walls, floors or other structures, protective sleeves (such as PVC sleeves) shall be installed to avoid damage to the down conductors.

3. Connection Construction of Grounding System

The connection of the lightning protection and grounding system is the key to ensuring the conductivity of the entire system. Poor connection will lead to increased contact resistance, which will affect the diversion effect of lightning current and even cause equipment damage due to ground potential counterattack. The connection construction shall comply with the following requirements:

Unified grounding system: The high-frequency UPS system shall adopt a unified grounding system, that is, the lightning protection grounding, equipment working grounding, and protective grounding (PE line) are integrated into a single grounding network. The grounding resistance of the unified grounding system shall be subject to the strictest requirement (generally ≤4Ω). It is strictly prohibited to set up separate grounding systems for different purposes to avoid ground potential difference and ground potential counterattack.
Connection between UPS equipment and grounding system: The metal shell of the high-frequency UPS, the chassis, the PE terminal of the input and output, and other metal parts must be reliably connected to the grounding network. The connection line shall be made of copper core cable with a cross-sectional area of not less than 16mm², and the connection shall be firm and tight. The connection point shall be treated with anti-corrosion to avoid loosening or corrosion affecting the grounding effect.
Connection of grounding network: The connection between horizontal grounding electrodes and vertical grounding electrodes, and between adjacent grounding electrodes shall be welding connection, and the welding quality shall meet the requirements. After welding, the welding seam shall be treated with anti-corrosion (such as applying zinc-rich paint and asphalt paint) to avoid corrosion of the welding seam and reduce the conductivity.
Inspection of connection points: After the connection is completed, each connection point shall be inspected one by one. Check whether the connection is firm, whether the welding seam is full, whether the anti-corrosion treatment is in place, and measure the contact resistance of the connection point (the contact resistance shall not be greater than 0.03Ω). For connection points that do not meet the requirements, rework shall be carried out in time.

4. Installation Construction of Surge Protector (SPD)

SPD is the key component to suppress transient overvoltage and protect high-frequency UPS equipment. Its installation quality directly affects the anti-surge effect. The installation construction shall strictly follow the manufacturer’s technical requirements and the following points:

Installation position: The SPD shall be installed as close as possible to the input and output ends of the high-frequency UPS, and the distance between the SPD and the UPS equipment shall not exceed 5m to reduce the inductive reactance of the line and ensure that the transient overvoltage can be suppressed in time. The signal SPD shall be installed at the inlet and outlet of the signal line of the UPS to prevent the transient overvoltage on the signal line from entering the UPS.
Wiring requirements: The incoming line and outgoing line of the SPD shall be as short and straight as possible, and the length shall not exceed 1m. The cross-sectional area of the SPD connection line shall not be less than 10mm² (copper core cable), and the connection shall be firm and tight. The ground wire of the SPD shall be directly connected to the grounding network, and shall not be connected in series with other ground wires or share the ground wire with other equipment to avoid the mutual influence of ground current.
Polarity and direction: The SPD shall be installed according to the correct polarity and direction (marked on the SPD body). For DC UPS systems, the positive and negative poles of the SPD shall be consistent with the positive and negative poles of the UPS input and output; for AC UPS systems, the phase line, neutral line and ground wire of the SPD shall be correctly connected to avoid reverse connection leading to SPD failure or equipment damage.
Protective measures: A fuse or circuit breaker shall be installed on the incoming line of the SPD to prevent the SPD from being damaged by overcurrent and causing short circuit. The rated current of the fuse or circuit breaker shall be matched with the SPD, generally 1.2-1.5 times the rated current of the SPD.
Labeling and inspection: After the installation of the SPD is completed, a clear label shall be pasted on the SPD, indicating the model, rated parameters, installation date and other information. At the same time, the SPD shall be tested to check whether it is intact and whether the indicator light is normal (the green light is normal, and the red light indicates failure).

III. Key Points of Post-Construction Inspection and Acceptance

Post-construction inspection and acceptance is the final link to ensure the quality of the lightning protection and grounding system. It is necessary to conduct a comprehensive inspection and test of the entire system to ensure that it meets the design requirements and relevant standards, and can effectively protect the high-frequency UPS equipment.

1. Visual Inspection

Carry out a comprehensive visual inspection of the lightning protection and grounding system, focusing on the following aspects:

Grounding electrode system: Check whether the layout of the grounding electrode is consistent with the design scheme, whether the burial depth meets the requirements, whether the backfill soil is tamped, and whether there is damage or corrosion to the grounding electrode.
Down conductor system: Check whether the routing, fixing and connection of the down conductor are correct, whether the welding seam is full, whether the anti-corrosion treatment is in place, and whether there is damage or loosening.
Connection points: Check whether all connection points (between grounding electrodes, between down conductors, between UPS equipment and grounding system, between SPD and grounding system) are firm and reliable, whether the anti-corrosion treatment is in place, and whether there is rust or loosening.
SPD installation: Check whether the installation position, polarity, direction and wiring of the SPD are correct, whether the fuse or circuit breaker is installed, whether the label is complete, and whether the indicator light is normal.

2. Electrical Performance Test

Electrical performance test is the core of post-construction inspection, mainly including grounding resistance test and SPD performance test:

Grounding resistance test: Use a professional grounding resistance tester to measure the comprehensive grounding resistance of the UPS system. The measurement points shall be selected at the connection point between the UPS equipment and the grounding system, and the measurement shall be carried out under dry weather conditions. The measured grounding resistance value shall not exceed the designed limit (generally ≤4Ω). If the measured value exceeds the limit, it is necessary to find out the reason (such as poor soil conductivity, insufficient grounding electrode layout) and take corresponding measures to rectify it until it meets the requirements.
SPD performance test: Use a surge generator to test the discharge current, response time and other parameters of the SPD. The test results shall be consistent with the rated parameters of the SPD. Check whether the SPD can effectively suppress transient overvoltage and whether there is leakage or failure. For signal SPD, test its insertion loss and return loss to ensure that it does not affect the normal transmission of signals.
Contact resistance test: Measure the contact resistance of key connection points (such as the connection between down conductor and grounding electrode, the connection between UPS and grounding system). The contact resistance shall not be greater than 0.03Ω. If the contact resistance is too large, it is necessary to reprocess the connection point (such as derusting, re welding) to reduce the contact resistance.

3. Acceptance and Documentation

After the visual inspection and electrical performance test are qualified, organize relevant personnel (supervision department, construction unit, equipment manufacturer) to carry out acceptance. The acceptance shall be based on the construction scheme, relevant national standards and equipment technical requirements. After the acceptance is passed, issue an acceptance report, which shall include the following contents:

Basic information of the project (project name, construction location, construction time, etc.).
Construction scheme and design requirements.
List of construction materials and inspection reports.
Records of on-site construction (construction photos, construction records, etc.).
Results of post-construction inspection and test (visual inspection records, grounding resistance test report, SPD performance test report, etc.).
Acceptance opinions and signatures of relevant parties.

At the same time, sort out all construction data and test reports, and file them for future maintenance and inspection.

IV. Key Points of Construction Safety and Maintenance

In addition to the above construction and inspection points, it is also necessary to pay attention to construction safety and later maintenance to ensure the long-term stable operation of the lightning protection and grounding system.

1. Construction Safety Points

Safety training: Before construction, conduct safety training for construction personnel, emphasizing the operation specifications, safety precautions and emergency handling methods of lightning protection and grounding construction.
Personal protection: Construction personnel must wear personal protective equipment (such as safety helmets, insulating gloves, insulating shoes) during construction to avoid electric shock or mechanical injury.
Power cut operation: When connecting the UPS equipment to the grounding system or installing SPD, it is necessary to cut off the power supply of the UPS and related equipment first, and hang a "power cut operation" sign to avoid electric shock accidents.
Weather protection: Avoid construction in thunderstorm weather to prevent lightning strikes. Construction in hot or cold weather shall take corresponding heatstroke prevention or cold protection measures.

2. Later Maintenance Points

Regular inspection: Conduct a comprehensive inspection of the lightning protection and grounding system every six months to one year, focusing on checking whether the grounding electrode, down conductor and connection points are corroded, loose or damaged, and whether the SPD indicator light is normal.
Regular test: Measure the grounding resistance of the system every year. If the measured value exceeds the limit, take corresponding measures to rectify it. Test the performance of the SPD every two years, and replace the failed SPD in time.
Anti-corrosion maintenance: For outdoor grounding electrodes and down conductors, reapply anti-corrosion paint every 2-3 years to avoid corrosion and ensure the conductivity of the system.
Emergency treatment: If the lightning protection and grounding system is damaged due to lightning strikes, construction or other reasons, it shall be repaired in time to avoid affecting the protection effect of the UPS system. After the repair, re test to ensure that it meets the requirements.

V. Conclusion

The lightning protection and grounding construction of high-frequency UPS is a systematic and rigorous project, which involves pre-construction preparation, on-site construction, post-construction inspection and later maintenance. Each link is closely linked and indispensable. To ensure the construction quality, it is necessary to strictly follow relevant standards and design requirements, select high-quality materials, standardize construction operations, and strengthen inspection and acceptance. Only in this way can the lightning protection and grounding system effectively divert lightning current, suppress transient overvoltage, avoid hidden dangers such as ground potential counterattack, and provide a safe and stable operating environment for high-frequency UPS equipment.

With the continuous development of high-frequency UPS technology and the increasing demand for power supply reliability, the requirements for lightning protection and grounding construction will become more and more strict. Construction personnel must continuously improve their professional quality and operational skills, master the key points of construction, and ensure that the lightning protection and grounding system can play its due role, thus protecting the safe and stable operation of key electrical equipment and promoting the healthy development of related industries.

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