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.
"Gold Standard" of grounding grids
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 top 5 reasons that gave pure copper this reputation.
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 the opposition to this current, allowing it to spread rapidly through the ground without causing dangerous ground potential rises (GPR).
- Flow Efficiency: The higher the conductivity, the lower the "contact resistance" and ohmic resistance of the conductor, facilitating the 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 Melt: 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
Like the meshes of grounding They are buried and must last for decades (30 to 50 years), so 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: Because it does not corrode, the cable maintains its original thickness over the years, ensuring that the conductivity designed on the first day 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" perfectly to the wires, creating a near-molecular (cold) connection that prevents moisture and oxygen from entering.
Resilience to Effort: In the event 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 attention to this detail to avoid potential damage to the braid.
In shortPure 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 reside solely in the robustness of the conductors or the low resistivity of the soil; it vitally depends on... integrity of connections.
"A grounding system is only as safe as its weakest point of connection."
The integrity of the connections must be analyzed from three fundamental perspectives:
- Electrical Continuity: The connection must not 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 connectors. An intact connection must withstand these stresses without suffering deformations, cracks, or loosening that would interrupt the flow path.
- Chemical Resistance (Corrosion): Since the meshes are buried, the connections are exposed to moisture and chemical agents in the soil. Their integrity depends on materials that prevent galvanic corrosion and keep the contact area clean and conductive for 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 risks involved. For better understanding, below we will briefly discuss the basic characteristics of materials commonly used in grounding grids.
Types of cables in a grounding mesh
(Electrolytic Copper × Copper-Plated Steel × Copper-Plated Aluminum × Steel)
The performance of a grounding grid depends directly on the cable material, its conductivity, thermal capacity, behavior during lightning strikes, durability, and mechanical strength.
Below is a comparative table containing the main points:
And for the connections, can I only use pure copper?
No, it's possible to use other types of alloys, 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 becoming increasingly adopted, making exothermic welding obsolete. Let's understand this a little better 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 primers 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 DependenceIt cannot be performed on rainy days or on very damp soil, as water vapor can cause explosions in the mold or porosity in the weld.
- Specific PPE for each type of connection.
Uniformity: It cannot be guaranteed that all different manufacturers will maintain the same characteristics for solder powder; this requires individual testing and measurements, and as shown in the table above, the difference can range from 20 to 80%.
Compression Fitting (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
Electrolytic copper connectors – Extrusion process
- They utilize 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 total absence of 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 metal in molds.
- During solidification, the following occur:
- internal porosities,
- microcracks,
- segregated regions with different concentrations of alloying elements,
- equiaxed and loosely compacted grains,
- 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 offer much better resistance to fault currents and lightning strikes, while maintaining low impedance and reducing overvoltages.
- Connectors cast in 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.
Cast connectors made of copper alloy.
- Reduced 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 lightning strikes
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 loop 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 technique, tooling, and materials. It is not merely an assembly procedure, but ensuring that every variable in the compression system—from the crimping tool to the connector metal—operates in accordance with all design requirements.
The triad of perfect crimping: connection system
The efficiency of a compression fitting lies in controlling the cold forming/fusion process. 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.
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 this energy will return to your installation seeking an outlet, which will likely be your equipment. Is it worth the risk?
The opinions and information expressed are the sole responsibility of the author and do not necessarily represent the official position of the author. Canal Solar.
