Lightning Protection Grounding System Construction Scheme

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​I. Project Background and Objectives​
With the increasing deployment of intelligent equipment in buildings, the risk of lightning damage has surged significantly. This scheme aims to establish a scientific and reliable lightning protection grounding system, ensuring effective protection for buildings and internal facilities during lightning strikes. It minimizes the risks of equipment damage and personal injury caused by lightning, providing a solid guarantee for the safe operation of facilities.

​II. System Design Principles​

1. ​Low-Resistance Grounding: Strictly control ground resistance (≤4Ω for general buildings, ≤1Ω for special areas like data centers) to ensure rapid dissipation of lightning current into the earth.
2. ​Unified Equipotential Bonding: Utilize a common grounding body to achieve equipotential interconnection between building foundations, metal structures, electrical installations, and lightning protection devices, eliminating potential differences and preventing backflash.
3. ​Strength and Durability Assurance: Grounding devices must possess sufficient mechanical strength and corrosion resistance to meet thermal and dynamic stability requirements of lightning current, ensuring long-term reliable operation.

​III. Core System Components and Implementation​

• ​Grounding Electrode Network (Foundation Grounding Grid)​​
• ​Material: Galvanized flat steel (e.g., 40mm×4mm) or copper-clad steel.
• ​Structure: Utilize building foundation reinforcement bars or a ring-shaped horizontal grounding belt to form a closed grid. Grid size is recommended ≤10m×10m, with denser arrangements in critical equipment areas.
• ​Burial Depth: ≥0.5m (below frost line), horizontally radiated.
• ​Vertical Grounding Electrodes​
• ​Layout: Distributed at grounding grid nodes or periphery to enhance current dissipation.
• ​Material: Galvanized angle steel (50mm×50mm×5mm×2500mm) or copper-bonded ground rods.
• ​Construction: Vertically driven into the ground; the top is reliably welded to the horizontal grounding belt. Spacing ≥2 times electrode length.
• ​Down Conductors​
• ​Layout: Utilize building column main reinforcement bars (≥Φ16mm diameter) or dedicated down conductors (≥25mm² copper cable/40mm×4mm galvanized flat steel), evenly distributed (spacing ≤18m).
• ​Connection: Achieve reliable electrical continuity with the roof air termination system, each floor's equipotential bonding ring, and the foundation grounding grid.
• ​Equipotential Bonding Network​
• ​Establishment: Install ground busbars in substation rooms, equipment rooms, and on each floor.
• ​Integration: Connect equipment enclosures, cable trays, metal pipes, information system grounding trunks, etc., to the nearest busbar.

​IV. Key Technologies and Processes​

1. ​Soil Improvement and Resistance Reduction: In areas of high soil resistivity, employ long-lasting physical grounding enhancers or techniques like electrolytic electrodes/deep-well grounding.
2. ​Reliable Connection Processes: Use exothermic welding (thermite welding) or dedicated connectors to ensure permanent electrical continuity and mechanical strength. Implement anti-corrosion treatment on welded joints.
3. ​Anti-Corrosion Treatment: Apply anti-corrosion coatings (e.g., anti-corrosion asphalt) strictly to welds. Select corrosion-resistant materials to ensure system lifespan.
4. ​Safety Spacing Control: Ensure safe separation distances between down conductors and metal pipes/cables. Implement isolation and insulation measures if spacing cannot be met.
5. ​Step Voltage Protection: Lay asphalt or crushed stone layers at entrances/exits and equipment grounding points to reduce ground potential gradients.

​V. Material and Equipment Selection Standards​

• ​Grounding Materials: Prioritize materials with high conductivity and corrosion resistance (copper and copper-clad steel).
• ​Connection Materials: Comply with national lightning protection standards like GB50057, ensuring current-carrying capacity and durability.
• ​Resistance-Reducing Materials: Use environmentally friendly, long-lasting grounding enhancers to avoid groundwater contamination.
• ​Testing Equipment: Ground resistance testers (e.g., 4-wire clamp meter) with high precision.

​VI. Construction and Acceptance​

• ​Civil Engineering Coordination: Synchronize construction of hidden components (e.g., foundation grounding grid) with building foundation work.
• ​Process Supervision: Fully supervise key stages like welding quality and burial depth.
• ​Completion Acceptance:
• ​Resistance Testing: Measure ground resistance value 72 hours after system completion to ensure compliance.
• ​Continuity Testing: Verify electrical continuity at all connection points.
• ​Documentation Archiving: Finalize as-built drawings, test reports, material certificates, and other technical documents.

​VII. Operation and Maintenance System​

• ​Regular Inspection: Re-test ground resistance annually before the rainy season (especially in critical areas) and assess connection point integrity.
• ​Corrosion Inspection: Prioritize checking corrosion on exposed connection points and welds.
• ​Emergency Response: Establish post-strike emergency inspection and repair protocols.
• ​Record Management: Maintain complete inspection data and maintenance records for dynamic system health management.