Grounding Posts

1. Material selection: Precise matching of performance and environment

Core material properties

Copper and copper alloys: High electrical conductivity (conductivity approximately 58MS/m), strong corrosion resistance, and the formation of an oxide film on the surface (such as Cu(OH)₂) can prevent further corrosion, suitable for high-frequency fault current scenarios. However, the cost is relatively high, and attention should be paid to the risk of theft.

Copper-plated steel: Combining the high electrical conductivity of copper with the strength of steel, the copper layer thickness is ≥0.254mm (in compliance with UL467/IEEE80 standards), and its corrosion resistance life can reach over 30 years. It is suitable for highly corrosive environments such as petrochemicals and power plants.

Stainless steel (such as 304/316L) : It has excellent corrosion resistance and is suitable for extreme environments like salt, alkali and seawater. It is resistant to electrochemical corrosion and has a service life of over 50 years.

Galvanized steel: An economical material, but with a low electrical conductivity (about 12%IACS), it is prone to rust in high-humidity or corrosive soil and requires regular maintenance (inspection every 6-8 years). It is suitable for dry and low-corrosion scenarios.

Prohibited materials: Threaded steel, due to its loose contact and poor corrosion resistance, and aluminum conductors, which are prone to oxidation, shall not be used for grounding bodies or grounding wires.

Principle of material compatibility

Grounding electrodes in the soil should preferably be made of copper, copper-plated steel or stainless steel, and hot-dip galvanized steel should be avoided as stipulated in GB50057-2010/GB55024-2022.

The reinforcing bars within the concrete foundation should be matched with the material of the soil grounding body to prevent electrochemical corrosion (such as the potential difference of approximately 1V when copper and steel are connected).

2. Processing technology: Precision forming and quality control

Forming process

Vertical/horizontal grounding body processing: Galvanized steel pipes (length ≥2.5m) need to be processed into inclined surfaces or flat pointed shapes to facilitate driving into the ground. One end of the Angle steel (such as 25mm×4mm) needs to be beveled with a sharp tip to ensure close contact with the soil.

Welding and connection: Arc welding, exothermic welding or bolt connection should be adopted. Ensure that the welding length is ≥2 times the diameter of the base material. The weld seam should be fully welded and undergo anti-corrosion treatment (such as asphalt coating).

Surface treatment: Copper plating, zinc plating, passivation (such as nitric acid passivation), PTFE coating or micro-arc oxidation to enhance corrosion resistance; Rolling threads enhances surface strength.

Key points of quality control

Dimensional accuracy: Diameter tolerance ±0.01-±0.05mm, length tolerance ±0.1mm, verticality ≤1%.

Welding quality: The weld seam should be free of cracks and pores and must pass tensile tests (tensile strength ≥300MPa) and bending tests.

Electrical conductivity: The grounding resistance should be ≤ the design value (such as 0.5Ω). In high-frequency scenarios, the skin effect should be considered to ensure that the conductivity is ≥20%IACS.

Corrosion resistance: Salt spray test ≥96 hours without red rust, high/low temperature cycle test, anti-electrochemical corrosion performance.

3. Installation and Inspection: Full-process reliability guarantee

Installation specifications

Positioning and verticality: Positioning is carried out using a theodolite or total station, with a verticality deviation of no more than 1%. The depth must meet the design requirements (such as ≥2.5m).

Connection method: Traditional welding is prone to deformation. It is recommended to use grounding pins, bolt connection or crimping to improve installation efficiency and consistency.

Protective measures: The grounding lead-out wire should be run through a non-magnetic steel pipe for protection to avoid contact with the structural reinforcing bars. After the foundation pit is excavated, it should be backfilled and compacted in a timely manner.

Inspection and Maintenance

Grounding resistance test: Use the three-pole method or clamp meter method. Regularly (at least once a year) test the resistance value. If it increases by more than 20%, corrosion or connection issues should be investigated.

Visual inspection: No cracks, rust or deformation, and the surface coating is uniform without peeling.

Environmental adaptability: In highly corrosive areas, the detection frequency should be increased, and corrosion-resistant materials should be replaced if necessary.

4. Design optimization and innovation paths

Structural optimization

Modular design: Quick-release interfaces or snap-on connections are adopted, facilitating maintenance and upgrades.

Heat dissipation and weather resistance: Add heat dissipation fins or heat-conducting coatings to enhance stability in high-temperature environments; Reduce environmental impact by using recycled materials or lightweight designs (such as aluminum alloy).

Special scenario customization: Heat-resistant alloys (such as Inconel 718) are selected for high-temperature environments, titanium alloys or PTFE coatings are used for corrosive environments, and optical measurement is adopted for high-precision scenarios to achieve sub-micron precision control.

Technological innovation

Surface engineering: Laser cladding, ion implantation or DLC coating to enhance wear resistance and corrosion resistance; Electrolytic polishing enhances surface finish (Ra≤0.2μm).

Intelligent processing: By using five-axis linkage machining centers or 3D printing technology, complex geometric structures (such as internal cooling channels) can be formed in one piece, reducing assembly errors.

Environmental Protection and Sustainability

Application of recycled materials: Recycling copper, stainless steel or aluminum alloy to reduce carbon footprint.

Green surface treatment: Water-based coatings replace oil-based lubrication, reducing VOC emissions; Chromium-free passivation treatment complies with environmental protection standards.

5. Industry Applications and Cases

Electricity and energy: Copper-clad steel grounding grids are adopted in substations and wind farms to ensure low resistance and long service life. The nuclear power plant selects stainless steel grounding electrodes to meet the requirements of high corrosion resistance and radiation resistance.

Buildings and infrastructure: The lightning protection system of high-rise buildings adopts copper-plated round steel down conductors, combined with equipotential bonding. The bridge structure adopts grounding pins instead of welding to enhance installation efficiency.

Industry and transportation: Titanium alloy grounding electrodes are used in chemical plants to resist chemical corrosion. The rail transit system adopts aluminum alloy grounding boxes, which are lightweight and highly weather-resistant.