Effective installation of lightning protection grounding devices for aluminum curtain walls requires a systematic approach encompassing design, materials, construction, connection, testing, and maintenance. The core objective is to form a comprehensive lightning protection system through reliable electrical connections, ensuring rapid discharge of lightning current to the ground and protecting the building and its occupants.
During the design phase, the lightning protection level and system architecture must be clearly defined. Based on the building's height, usage, and local lightning activity intensity, the lightning protection level (e.g., Level II or III) should be determined, and a three-dimensional protection system of "equipotential bonding ring + down conductor + grounding grid" should be designed according to the "Code for Design of Lightning Protection of Buildings." The equipotential bonding ring is laid horizontally along the building's exterior facade, typically utilizing the aluminum curtain wall frame or a separately installed galvanized round steel. Down conductors are laid along building corners or evenly distributed, with spacing meeting code requirements. The grounding grid is implemented through pile foundations, reinforcing steel in ground beams, or artificial grounding electrodes, ensuring the grounding resistance meets design values (e.g., no more than 1 ohm).
Material selection must balance conductivity and durability. For lightning protection main materials, hot-dip galvanized steel (such as round steel and flat steel) should be preferred, and its zinc layer thickness must meet the standard (e.g., not less than 85μm) to prevent corrosion of buried parts. Copper core wires or copper busbars can be used for connecting conductors to reduce resistance loss. Stainless steel gaskets are used to isolate dissimilar metals (such as aluminum columns and steel supports) to avoid electrochemical corrosion. Welding rods must be compatible with the base material (e.g., E43XX type) to ensure weld strength. All materials must be inspected for certificates of conformity and test reports upon arrival, and key performance characteristics (such as conductivity and zinc layer thickness) must be sampled and retested.
The construction process must strictly adhere to process standards. First, lightning protection connectors (such as steel plates and reinforcing bars) must be pre-embedded during the main structure construction, and positional deviations must be controlled within allowable limits. During the aluminum curtain wall keel installation stage, vertical columns should be welded to the pre-embedded parts using angle iron, with stainless steel gaskets added, and the welding length must meet specifications (e.g., double-sided welding not less than 100mm). When connecting horizontal keels to columns, they must be secured with stainless steel bolts using aluminum alloy angle brackets, ensuring electrical continuity. Expansion joints should use "Ω"-type jumpers to allow space for temperature deformation.
Equipotential bonding is a crucial aspect of the lightning protection system. The aluminum curtain wall must form an electrical path with the main lightning protection device. Specific measures include: welding the aluminum curtain wall metal frame to the equipotential ring using flat steel or copper cable; laying connecting conductors after the door and window frames are positioned and before the wall decoration layer is applied, with the leads lapped and welded to the lightning protection down conductors; and connecting conductive components such as metal railings and decorative strips to the lightning protection system as close as possible. The oxide film at the connection points must be removed, conductive paste applied, and the transition resistance tested (generally not exceeding 0.03 ohms).
The installation of the grounding device must ensure reliability. Grounding electrodes (such as angle steel or steel pipes) should be driven vertically into the ground, with the top at least 0.6 meters above the ground; the grounding wire (flat steel) must be welded on three sides, and the welded areas should be treated with anti-corrosion measures (such as applying anti-rust paint); when connecting the grounding grid to the down conductors, bolts or welding should be used for fastening, and disconnection clips should be installed for inspection. For areas with high soil resistivity, grounding resistance can be reduced by replacing the soil, adding resistance-reducing agents, or installing additional grounding electrodes.
After the lightning protection system is installed, a comprehensive test is required. Use a grounding resistance tester to measure the resistance value of the grounding device to ensure it meets design requirements; use a micro-ohmmeter to test the contact resistance at the joints of metal components to verify the equipotential bonding effect; use an insulation resistance tester to check the insulation performance between non-conductive materials and the metal structure to prevent unexpected lightning current conduction. Test results must be recorded and archived as acceptance criteria.
Routine maintenance is crucial for ensuring the long-term effectiveness of the lightning protection system. Regularly check lightning arresters (such as lightning strips and lightning rods) for cracks, corrosion, or mechanical damage, and repair or replace them promptly; check whether the down conductors are loose or broken, and whether the protective tubes are damaged; check for soil subsidence around the grounding device to prevent exposed grounding electrodes; conduct a special inspection before the rainy season to remove bird nests, debris, and other potential short-circuit hazards. Any components that fail the test must be rectified immediately to ensure the lightning protection system is always in good working order.
