Marcelo Lopes

The grounding grid is one of the cornerstones of safety in electrical systems, ensuring the effective drainage of fault currents and lightning strikes to the ground. The efficiency of this drainage depends not only on the geometric design of the mesh and the resistivity of the soil, but also — and decisively — on the conductivity of the materials used in the connections, and, no less importantly, on the physical and chemical characteristics of the material used in the mesh. Pure (electrolytic) copper is considered the gold standard for critical grounding grids due to a set of physical and chemical properties that ensure the system not only functions under normal conditions but also survives extreme events. Below we can list the 5 main reasons that gave pure copper its fame. Unsurpassed Electrical Conductivity (99,9% IACS) Electrolytic copper has the highest conductivity among commercial metals. This is vital because: Low Impedance: In atmospheric discharges (lightning), the current has a high frequency. Copper minimizes resistance to this current, allowing it to spread rapidly through the ground without causing dangerous ground potential rise (GPR). Flow Efficiency: The higher the conductivity, the lower the "contact resistance" and ohmic resistance of the conductor, facilitating its path to ground. High Thermal Stability: During a short-circuit fault, the conductor can be subjected to extremely high temperatures in fractions of a second. Resistance to Melting Point: Copper has a high melting point and thermal capacity that allows it to withstand immense current densities without melting or degrading, unlike copper or aluminum alloys that can fail prematurely. Heat Dissipation: It dissipates the heat generated by the Joule effect much faster than steel or aluminum, protecting the physical integrity of the mesh. Exceptional Corrosion Resistance: Because grounding meshes are buried and must last for decades (30 to 50 years), chemical durability is crucial. Electrochemical Potential: Copper is a noble metal and is stable in the soil. It does not suffer from severe galvanic corrosion like steel or aluminum (which would require protective layers that can break down). Cross-section Maintenance: By not corroding, the cable maintains its original thickness over the years, ensuring that the designed carrying capacity remains the same after 30 years. High Ductility and Malleability: These mechanical properties facilitate installation and ensure post-installation safety: Compression Connections: Pure copper deforms plastically without cracking. This allows compression connectors to "mold" themselves perfectly to the wires, creating a near-molecular (cold) connection that prevents moisture and oxygen from entering. Stress Resilience: In case of ground settlement or vibrations, the copper bends without breaking, maintaining the electrical continuity of the mesh. Compatibility with Exothermic Connections: Soldering, in its original concept, was developed to provide molecular fusion with the pure copper of the conductor, resulting in joints that are a continuation of the conductor itself. Exothermic soldering, when used with materials other than pure copper, can have the opposite effect and even damage the connection due to the high concentration of heat. The designer must pay close attention to this detail to avoid potential damage to the mesh. In short, pure copper is chosen for critical systems because it is the only material that combines maximum electrical performance with extreme longevity underground. However, the efficiency of this system does not depend solely on the robustness of the conductors or the low resistivity of the soil; it vitally depends on the integrity of the connections. "A grounding system is only as safe as its weakest connection point." The integrity of the connections must be analyzed from three fundamental perspectives: Electrical Continuity: The connection cannot become a "bottleneck" or a point of high resistance. If the interface between two conductors has a conductivity lower than that of the cable itself, it will create a localized potential drop and heating due to the Joule effect. Mechanical Stability: During a lightning strike, electrodynamic forces and rapid thermal expansion can exert violent pressures on the connectors. An intact connection must withstand these stresses without suffering deformations, cracks, or loosening that would interrupt the flow path. Chemical Resistance (Corrosion): Because the meshes are buried, the connections are exposed to moisture and chemical agents in the soil. Integrity depends on materials that prevent galvanic corrosion and keep the contact area clean and conductive over decades. So now, can I only use pure copper cables? Although pure electrolytic copper is the gold standard for maximum performance, the market offers alternative materials that can be applied in specific scenarios. However, choosing an option other than pure copper requires the designer to be fully aware of the technical differences and the risks involved. For better understanding, below we will briefly discuss the basic characteristics of the materials commonly used in grounding grids. Types of cables in a grounding mesh (Electrolytic Copper × Copper-clad Steel × Copper-clad Aluminum × Steel) The performance of a grounding mesh depends directly on the cable material, its conductivity, thermal capacity, behavior in atmospheric discharges, durability, and mechanical resistance. Below is a comparison table containing the main points: And regarding the connections, can I only use pure copper? No, it is possible to use other types of alloy, however, because extruded pure copper is one of the most ductile and malleable materials, excellent for cold forming, the standard for copper compression connectors is being adopted more and more each day, making exothermic welding obsolete. Let's understand a little more below: Types of Connections and their Technical Realities Exothermic Welding: The Declining Standard Although it offers molecular fusion and superior conductivity, exothermic welding faces severe logistical barriers: Critical Storage: Gunpowder and initiators require strict safety protocols and specific storage locations to prevent explosions. Application tools: which may vary depending on the type of mold and connection to be made. Climate Dependence: It cannot be performed on rainy days or in very humid soils, as water vapor can cause explosions in the mold or porosity in the weld. Specific PPE for each type of connection. Uniformity: It is not possible to guarantee that all different manufacturers maintain the same characteristics for welding powder; this requires individual testing and measurements, and as shown in the table above, the variation can be from 20 to 80%. Compression Connection (Extruded Electrolytic Copper and Cast Copper Alloy) Currently, compression is the most balanced option for critical grounding systems. It uses hydraulic tools to deform the copper connector and specific dies specially designed for maximum performance. Advantage: It can be installed in any weather condition and does not require hazardous materials. Differences between compression connectors and electrolytic copper connectors – Extrusion process. They use high-purity electrolytic copper (≥ 99,9% IACS). The extrusion process guides the crystalline structure along the material flow. The resulting piece has: elongated and compact grains, virtually no porosity, high metallic density, excellent continuity, and uniformity of conductivity. Direct benefit: Extremely high thermal conductivity and dissipation capacity, even under impulsive currents from lightning strikes. We guarantee that the batch will have the same standard and characteristics in terms of conductivity and material. Copper alloy connectors – Casting process. The casting process involves melting and solidifying the metal in molds. During solidification, the following occur: internal porosities, microcracks, segregated regions with different concentrations of alloying elements, equiaxed and poorly compacted grains, and lower metallic density. Effect on conductivity: The presence of pores and the heterogeneity of the grains increase resistivity, substantially decreasing the ability to conduct impulse currents. Electrical Properties Electrical Conclusion Extruded connectors made of electrolytic copper withstand fault and lightning currents much better, maintaining low impedance and reducing overvoltages; Cast connectors made of copper alloy are more susceptible to failure. Mechanical Properties: Extruded electrolytic copper. High ductility. High mechanical strength and tensile strength. Better response to high compression (essential in compression connectors). It deforms without cracking. Connectors cast in copper alloy. Lower ductility. More rigid and brittle. Sensitive to cracking under mechanical stress. Internal porosity increases the risk of rupture during compression. Practical consequence: A fused connector can crack during compression or under repetitive thermal stress. It cannot be guaranteed that all items in a batch have the same characteristics; this requires individual testing and measurements, and as shown in the table above, the difference can vary from 20 to 80%. 4. Behavior under short-circuit currents and atmospheric discharges. Extruded connector (electrolytic copper): The dense and homogeneous structure allows for much faster heat dissipation. It is more resistant to the piel effect (high-frequency currents from surges). It maintains integrity even at peaks of hundreds of kA. Cast connector (copper alloy): Zones of lower conductivity create hot spots. Increased risk of melting, charring, and rupture. It does not distribute the flow of impulse current adequately. Risks Associated with the Use of Cast Copper Alloy Connectors: Increased mesh impedance, raising touch and step voltages. Thermal failures during discharges. Mechanical rupture during compression or operation. Accelerated deterioration due to galvanic or intergranular corrosion. Total loss of electrical continuity, compromising the grounding. How is the perfect connection made between the grounding meshes? The integrity of an electrical interface is a direct result of the synergy between technology, tools, and supplies. This is not merely an assembly procedure, but about ensuring that every variable in the compression system—from the pliers to the connector metal—operates in accordance with all design requirements. The triad of perfect crimping: connection system. The efficiency of a compression connection lies in the control of cold forming/fusion. For this to occur, the use of calibrated hydraulic presses is vital, as they provide the necessary energy for uniform deformation. Additionally, the dimensional precision of the dies prevents the formation of burrs or points of undercompression, phenomena that result in high contact resistances and anomalous heating (Joule effect). Connector selection is where many projects fail due to negligence. Components with inadequate metal purity or substandard alloys accelerate degradative processes such as galvanic corrosion and mechanical fatigue. In critical infrastructure, such as grounding grids or bimetallic transitions in photovoltaic plants, material reliability is the only barrier against catastrophic failures that could compromise the safety of people and equipment. Choosing technical compatibility between tool, matrix, and connector is an asset management strategy. By ensuring a robust connection, the Mean Time Between Failures (MTBF) and operational costs associated with corrective maintenance and premature replacements are drastically reduced. Ultimately, strict adherence to high-quality connectivity standards is not a differentiator, but a mandatory prerequisite for the resilience and longevity of any modern electrical system. In conclusion, energy conservation, often associated with energy efficiency, begins with the correct specification and application of electrical connections. According to current technical standards, all equipment must be powered by appropriate connectors and terminals capable of ensuring a reliable, continuous, and safe connection, minimizing risks to human safety and the electrical system. Poorly executed connections not only pose a risk to the installer, but also compromise the safety and performance of the powered equipment. In addition to safety aspects, power quality is directly related to the ability to provide a stable, clean, and interference-free power supply. Choosing components based solely on cost can result in premature failures, overheating, electrical losses, and damage to high-value equipment, generating losses significantly greater than the investment in correctly specified connectors. Remember: The grounding grid is the most important path for dissipating spurious currents, fault currents, and atmospheric discharges. If it fails, all that energy will return to your installation seeking an outlet, which will likely be your equipment. Is it worth the risk?

Marcelo Lopes

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