The specification parameters of H07V-K 35mm² and 25mm² green-Yellow Earth Cables are carefully designed to fully meet the stringent requirements for safe grounding of electrical systems, providing precise adaptation to grounding needs in different scenarios.
For the 25mm² cable, its conductor structure is composed of multiple strands of fine Copper Wires tightly stranded. The diameter of a single copper wire is precisely controlled at 0.25mm±0.01mm, with a total of 420 strands. This multi-strand stranding design not only enhances the Flexibility of the cable but also greatly increases the conductive area. The overall conductor diameter is approximately 6.5mm±0.2mm, and the cross-sectional area is strictly guaranteed to be 25mm²±0.5mm². At 20°C, its DC resistance, after multiple tests, is stably controlled at no more than 0.727Ω/km. This low resistance characteristic ensures that when a device leaks electricity, the fault current can be conducted to the ground at the fastest speed, reducing the risk of electric shock. The rated voltage of this cable is 450/750V, where 450V is the phase-to-ground voltage and 750V is the phase-to-phase voltage, fully complying with the voltage standards for grounding circuits in low-voltage electrical systems. It can operate stably in AC 50Hz or 60Hz circuits, adapting to various power systems.
The 35mm² cable has more carrying advantages in terms of specifications. The diameter of a single copper wire is 0.28mm±0.01mm, with a total of 580 strands. The conductor diameter is approximately 8mm±0.2mm, and the cross-sectional area is 35mm²±0.8mm². The DC resistance at 20°C is no more than 0.524Ω/km. Compared with the 25mm² cable, it can carry a larger fault current, making it suitable for grounding of large electrical systems with higher current capacity requirements. Similarly, its rated voltage is 450/750V, and it can work stably in AC 50Hz or 60Hz circuits, meeting the grounding needs of various high-power equipment.
In terms of insulation layer parameters, the insulation thickness of the 25mm² cable is 1.2mm±0.1mm, and that of the 35mm² cable is 1.4mm±0.1mm. The insulation layer is made of high-density PVC material with a dielectric strength exceeding 20kV/mm. It has passed strict voltage withstand tests, withstanding 2500V AC voltage for 1 minute without breakdown, effectively isolating the grounding circuit from other live parts and eliminating the risk of electric leakage. At 20°C, the insulation resistance of both cables is not less than 100MΩ·km, and even in a humid environment with 90% relative humidity, the insulation resistance can still be maintained above 50MΩ·km, ensuring the stability of insulation performance.
In terms of temperature resistance, the long-term operating temperature range of both cables is -15°C to 70°C. In a low-temperature environment of -15°C, the cable can still maintain good flexibility, and the insulation layer does not crack when bent; in a high-temperature environment of 70°C, the insulation layer does not soften or deform, and the electrical performance is stable. It can withstand a high temperature of 90°C for a short time (within 30 minutes), which can cope with short-term overload of equipment or sudden rise in ambient temperature.
In terms of mechanical properties, the minimum bending radius of both cables is 4 times the outer diameter of the cable. The static bending radius of the 25mm² cable is not less than 26mm, and the dynamic bending radius (under frequent bending) is not less than 39mm; the static bending radius of the 35mm² cable is not less than 32mm, and the dynamic bending radius is not less than 48mm. This characteristic allows the cable to be flexibly laid in narrow and complex spaces such as inside electrical cabinets and wall interlayers, reducing installation difficulty. In addition, the tensile strength of the cable is not less than 12MPa, and the elongation at break is not less than 150%, which can withstand stretching and extrusion during installation and use, prolonging the service life.
H07V-K 35mm² and 25mm² Green-Yellow Earth Cables play a key role in grounding protection in many fields with their unique performance and identification, ensuring the safe operation of electrical systems.
In the industrial field, the 25mm² cable is widely used. Small and medium-sized motors in industrial production lines, usually with power ranging from 5-30kW, must have their metal casings reliably grounded. The 25mm² cable can quickly conduct the fault current generated when the motor leaks to the ground, avoiding motor damage and personal electric shock. The control cabinet, as the control core of the production line, contains many internal electrical components, and the consequences of electric leakage are serious. Using a 25mm² cable to connect the control cabinet to the grounding electrode can form a reliable protective grounding. In addition, for mobile equipment such as electric welders and grinders in the workshop, the grounding core wire in their power cords often uses 25mm² cables to ensure that the grounding is always good during the movement of the equipment.
The 35mm² cable plays an important role in large industrial equipment and systems. The transformer in a factory is a key equipment for power distribution, and the grounding of its casing and iron core must use high-reliability cables. The 35mm² cable can carry the huge short-circuit current generated when the transformer fails, protecting the transformer and the entire power system. High-voltage switchgear contains high-voltage circuit breakers, disconnectors and other equipment, and its grounding circuit requires 35mm² cables to meet the grounding requirements of high voltage and large current. The main grounding trunk of an industrial plant connects all the grounding branches of the equipment in the plant, and the 35mm² cable can 汇总 the current from each branch and conduct it to the grounding electrode, forming a complete industrial grounding network.
In commercial buildings, the two types of cables have different applications. Each floor's distribution room in a commercial complex is equipped with a local grounding network for connecting various electrical equipment on that floor. The 25mm² cable, with its appropriate current-carrying capacity and flexibility, is an ideal choice for connecting the local grounding network. The metal casings of refrigeration equipment and central air-conditioning outdoor units in large supermarkets are often grounded with 25mm² cables to ensure safety when the equipment is used in humid environments. The main grounding trunk of a commercial building needs to connect the local grounding networks of each floor and connect to outdoor grounding electrodes. The 35mm² cable can meet this high-capacity grounding demand, ensuring the grounding reliability of the entire building's electrical system.
In the field of civil buildings, 25mm² cables are often used for grounding of household distribution boxes in residential buildings. Each household's distribution box is connected to the building's grounding trunk through a 25mm² cable. When electrical appliances in the home leak, the current can be quickly conducted to the ground through this cable, protecting the residents' safety. In the elevator machine room of high-rise residential buildings, the metal parts of the elevator equipment must be reliably grounded. The 25mm² cable can adapt to the vibration during elevator operation and maintain stable grounding. The 35mm² cable is used for the main grounding network of residential communities, connecting the grounding trunks of all buildings in the community, forming a grounding system covering the entire community, effectively resisting the hazards caused by lightning strikes and electric leakage.
In special places such as hospitals and data centers, the two types of cables also play important roles. The equipment in hospital operating rooms has extremely high requirements for grounding. Any slight electric leakage may affect the normal operation of medical equipment and patient safety. The 25mm² cable provides reliable protective grounding for these precision equipment. The grounding circuits of server cabinets and UPS power supplies in data centers require 25mm² cables to ensure the stability of the equipment during high-load operation. The main grounding system of a data center, due to the large number of connected equipment and large grounding current, must use 35mm² cables as the main grounding trunk to ensure the electrical safety of the entire data center.
Material
The material selection of H07V-K 35mm² and 25mm² green-yellow earth cables is the core guarantee for their excellent performance. The materials of the conductor and insulation layer are strictly screened and optimized.
The conductor is made of high-purity electrolytic copper with a purity of more than 99.95%, including copper content ≥99.95% and total content of impurities such as iron, lead, and tin ≤0.005%. High-purity copper has excellent conductivity, with a conductivity of 101% IACS (International Annealed Copper Standard), which is much higher than that of ordinary copper materials. This makes the DC resistance of the cable extremely low, enabling efficient conduction of fault current. At the same time, this high-purity copper has good ductility and toughness, and is not easy to break after multiple drawing and stranding, ensuring the stability of the conductor structure. To further improve the performance of copper, the conductor is also annealed. In a nitrogen-protected environment, the copper material is heated to 400-450°C, kept warm for 2-3 hours, and then slowly cooled to eliminate internal stress, enhance its flexibility and fatigue resistance, so that the conductor can withstand frequent bending and vibration.
The insulation layer is made of high-quality polyvinyl chloride (PVC) material, with various modifiers added for performance optimization. Among them, the plasticizer is dioctyl phthalate (DOP) with an addition ratio of 18%, making the PVC material have good flexibility, ensuring that the cable can still bend flexibly in low-temperature environments; the stabilizer is a calcium-zinc composite stabilizer, replacing the traditional lead salt stabilizer, which is not only environmentally friendly and non-toxic but also can improve the aging resistance of the insulation layer, prolonging the service life of the cable; the flame retardant is antimony trioxide with an addition amount of 6%, making the insulation layer reach UL94 V-0 flame retardant standard, which can self-extinguish quickly when exposed to fire and does not produce toxic thick smoke.
The density of this PVC Insulation layer is 1.45g/cm³, and the Shore hardness is 70 Shore A, with excellent oil resistance. When in contact with industrial oils such as engine oil and diesel, after 24-hour immersion test, the volume change rate is ≤5%, and the weight change rate is ≤3%, which can maintain stable performance in industrial oil-contaminated environments. In terms of wear resistance, after the Taber wear test (load 500g, 1000 revolutions), the wear amount is ≤8mg, which can withstand friction and scratch during installation and use.
Style
Both cables have a single-core structure. The single-core design helps reduce signal interference, ensures smooth conduction of grounding current, and also makes the cable more flexible, facilitating laying in complex environments. The appearance of the cable is round, with a smooth and flat surface, without defects such as bubbles, depressions, and scratches. This rounded shape reduces the resistance during laying and also reduces the risk of the insulation layer being punctured by sharp objects.
The most prominent style feature is its green-yellow color identification, with green and yellow alternating distribution, and the color band width is uniform, about 5-10mm, complying with the grounding identification standards of the International Electrotechnical Commission (IEC). This eye-catching color combination can quickly identify the grounding circuit, avoid confusion with phase lines and neutral lines, prevent misconnection from the source, and ensure the accuracy of the grounding system.
In addition to the green-yellow color identification, the surface of the cable is also clearly printed with product information, including model (H07V-K), specification (25mm² or 35mm²), rated voltage (450/750V), production batch number, meter marking, and certification marks (such as CE certification), etc. These marks use temperature-resistant ink, which remains clearly visible after baking at 90°C, facilitating identification during construction and later traceability.
The standard lengths of the cable are 100 meters/roll and 50 meters/roll, meeting the needs of different project scales. The 100-meter/roll cable is packaged with a sturdy wooden reel, with a reel diameter of 500mm and a width of 200mm; the 50-meter/roll cable uses a plastic reel, with a diameter of 300mm and a width of 150mm, which is convenient for transportation and storage.
The production process of H07V-K 35mm² and 25mm² green-yellow earth cables is complex and precise. Every link from raw material processing to finished product inspection is strictly controlled to ensure that the product quality meets high standards.
The preparation process of the conductor is rigorous and meticulous. The first step is the smelting of copper rods. Electrolytic copper ingots with a purity of 99.95% are selected and heated to 1150°C in a power frequency induction furnace to melt them. Then, an appropriate amount of phosphor copper deoxidizer is added to the molten copper liquid to remove oxygen and impurities in the copper liquid and improve the purity of copper. Subsequently, the molten copper liquid is rolled into Φ8mm copper rods through a continuous casting and rolling machine. The tensile strength of the copper rods is controlled at 280MPa, and the elongation is ≥35%, ensuring that the copper rods have good processing performance.
The copper rod is drawn into fine copper wires through the drawing process. A continuous wire drawing machine is used, equipped with 20 drawing dies. The die material is polycrystalline diamond (PCD), which has extremely high wear resistance and precision. During the drawing process, the copper rod starts from Φ8mm and passes through dies with different apertures in turn, gradually drawn into fine copper wires of 0.25mm (25mm² cable) or 0.28mm (35mm² cable). The drawing speed is controlled at 12m/s, and emulsion is used for cooling and lubrication. The temperature of the emulsion is maintained at 30°C to prevent the copper wire from oxidizing or breaking due to overheating during the drawing process. After drawing, the copper wire is annealed. In a continuous annealing furnace, a mixed gas of hydrogen and nitrogen (volume ratio 1:9) is used as the protective gas, the heating temperature is 420°C, and the annealing speed is 6m/s, so that the tensile strength of the copper wire is reduced to 200MPa, and the elongation is increased to 45% to enhance its flexibility.
Multiple strands of copper wires are stranded to form a conductor by a high-precision stranding machine. The 25mm² cable is stranded with 420 strands of copper wires, and the 35mm² cable is stranded with 580 strands of copper wires. During stranding, a regular stranding method is adopted to ensure uniform tension of each strand of copper wire. The stranding pitch is controlled at 12 times the conductor diameter. The stranding pitch of the 25mm² cable is 78mm, and that of the 35mm² cable is 96mm. Such a pitch can not only ensure the flexibility of the conductor but also prevent the Stranded Conductor from loosening. During the stranding process, the outer diameter and roundness of the conductor are monitored in real time through an online monitoring system. Once the deviation exceeds ±0.02mm, the stranding parameters are automatically adjusted immediately to ensure stable conductor quality.
The extrusion molding of the insulation layer is a key process. A special extruder is used, with a screw diameter of 80mm and a length-diameter ratio of 25:1. PVC Insulation Material particles are added to the extruder hopper, and the barrel temperature is controlled in sections: feeding section 150°C, compression section 170°C, homogenization section 190°C, and die head temperature 200°C, ensuring that the PVC material is fully melted and plasticized. The molten PVC material forms a green-yellow insulation layer outside the conductor through a specially designed two-color extrusion die. The design of the die ensures the uniform distribution of the green-yellow color and the concentricity of the insulation layer, with an eccentricity of ≤3%. The extrusion speed is consistent with the traction speed of the conductor, which is 15m/min. The insulation layer is cooled and shaped through a vacuum sizing sleeve, the cooling water temperature is 25°C, and the cooling length is 4 meters, so that the insulation layer is quickly solidified and the size is stable.
The extruded cable is printed with a laser printer, clearly printing product information on the cable surface, with high print clarity and strong adhesion. Subsequently, the cable is tested for insulation performance by a spark tester, applying a high voltage of 5kV to ensure that the insulation layer has no pinholes and other defects. The qualified cables are wound onto reels, maintaining appropriate tension during winding to avoid loose cables or distortion.
The finished product inspection is strictly controlled. Sampling inspection is carried out for each batch of cables. The inspection items include appearance inspection (surface smoothness, color uniformity, clarity of identification), dimension measurement (conductor diameter, insulation thickness, cable outer diameter), electrical performance test (DC resistance, insulation
resistance, dielectric strength), mechanical property tests (tensile strength, elongation at break, bending performance), and temperature resistance tests (performance changes after being placed in a 70°C environment for 1000 hours). Only cables that meet the standards in all test items are allowed to leave the factory.
The packaging design of H07V-K 35mm² and 25mm² green-yellow earth cables fully considers the needs of product protection, transportation, and storage, ensuring that the cables are not damaged during the entire circulation process.
For the 100-meter/roll cable, it is packaged with a wooden reel. The reel is made of high-strength pine, with a diameter of 500mm, a width of 200mm, and a reel shaft diameter of 100mm. The load-bearing capacity of the reel reaches 50kg, which can withstand the weight of the cable and the pressure during transportation. Both sides of the reel are equipped with 15mm thick cardboard baffles, and the edges of the baffles are reinforced with metal strips to prevent the baffles from deforming during handling. When the cable is wound onto the reel, the tension is uniform and the arrangement is neat. The outer layer is wrapped with a 0.08mm thick polyethylene film, and both ends of the film are folded inward by 100mm and sealed with tape to form a moisture-proof and dust-proof protective barrier. A detailed label is attached to the side of the reel. The label is made of waterproof material, printed with product name, model, specification, length, rated voltage, production batch number, production date, manufacturer information, and warning signs such as "moisture-proof" and "handle with care".
The 50-meter/roll cable is packaged with a plastic reel. The reel is made of high-density polyethylene (HDPE), which has the characteristics of impact resistance and corrosion resistance. It has a diameter of 300mm, a width of 150mm, and a reel shaft diameter of 80mm. After the cable is neatly wound, it is also wrapped with a polyethylene film, and the same label information as the wooden reel is attached to the side of the reel.
For small-batch retail packaging, sealed plastic woven bags are used, each of which can hold 10-meter or 20-meter cables. The thickness of the woven bag is 0.1mm, which has good tensile strength. The bag mouth is designed with a rope buckle for easy opening and sealing. The bag also contains a product certificate and an instruction manual to help users understand product information and usage methods.
All packages have passed the drop test. After dropping three times from a height of 1.2 meters, the packages are not damaged, and the cables are not loose or damaged, ensuring that they can withstand a certain impact during transportation.
The transportation of H07V-K 35mm² and 25mm² green-yellow earth cables strictly follows relevant regulations to ensure that the products are delivered safely and timely.
Before transportation, a comprehensive inspection of the cable packaging is carried out to confirm that the reels are not loose, the baffles are not damaged, the films are not torn, and the label information is complete and clear. For cables packaged with wooden reels, palletized transportation is adopted. Each pallet can hold 8-10 reels of cables, with a pallet size of 1200mm×1000mm and a load-bearing capacity of 500kg. The cable reels are neatly arranged on the pallet and fixed with packing belts. The packing belts are 16mm wide polyester fiber belts, and each reel of cable is fixed with at least 4 packing belts to ensure that they do not shake or topple during transportation.
For long-distance transportation (more than 500km), closed containers or box trucks are used, which have the functions of rainproof, sunproof, and dustproof. The temperature inside the container or truck is controlled between 5°C and 35°C. In summer, ventilation equipment or sunshades can be used to prevent the temperature from being too high; in winter, in cold areas (temperature ≤-10°C), thermal insulation measures such as covering with thermal insulation blankets are taken to avoid the cable from being affected by extremely low temperatures.
During transportation, it is forbidden to stack heavy objects on the cable reels to prevent the reels from being crushed and the cables from being deformed. The transportation vehicle should drive smoothly, avoiding sudden acceleration, braking, and sharp turns to prevent the cable reels from colliding with each other. Loading and unloading are carried out by forklifts or cranes, and special spreaders are used to hook the reel shafts to avoid damaging the reels and cables.
The delivery of H07V-K 35mm² and 25mm² green-yellow earth cables is efficient and standardized, ensuring that customers receive the products in a timely manner.
After the customer places an order, the warehouse staff will check the order information, including product model, specification, quantity, and delivery address, and then pick the goods according to the order. The picking process strictly follows the first-in-first-out principle to ensure that the products delivered are within the shelf life. After picking, the products are inspected again to confirm that the packaging is intact and the product information is consistent with the order.
For orders with a small quantity (less than 5 rolls), they can be delivered by express within 24 hours after the order is confirmed. For large quantities (more than 5 rolls), they are delivered by logistics, and the delivery time is determined according to the distance, usually 3-7 days. The customer will be informed of the logistics information, including the waybill number and the contact information of the logistics company, so that the customer can track the transportation status of the goods.
Before delivery, the outer packaging of the products is marked with the customer's name, contact information, and delivery address to ensure accurate delivery. For special customers, such as those with urgent needs, we can provide expedited delivery services, and arrange transportation vehicles and personnel in a timely manner to shorten the delivery time.
We provide sample services for H07V-K 35mm² and 25mm² green-yellow earth cables to help customers test and evaluate the products before purchasing in large quantities.
The sample specifications are usually 1-meter lengths of 25mm² and 35mm² cables, which are packaged in small plastic bags with product labels and instructions. Customers can apply for samples through the official website, email, or phone. After receiving the sample application, the staff will confirm the customer's information and needs, and send the samples within 3 working days.
The sample fee is usually waived, but the customer needs to bear the freight. For regular customers or customers who intend to place large orders, the freight can be borne by our company. After receiving the samples, customers can conduct tests such as appearance inspection, dimensional measurement, and electrical performance testing to verify whether the product meets their needs.
Our technical staff can provide professional guidance for sample testing, answer the customer's questions about the test methods and standards, and provide test reports and related technical data if necessary to help customers make purchasing decisions.
We provide comprehensive after-sales services for H07V-K 35mm² and 25mm² green-yellow earth cables to solve the problems encountered by customers in the process of using the products.
If the product has quality problems within the warranty period (12 months from the date of delivery), such as insulation layer cracking, conductor oxidation, or unqualified electrical performance, customers can contact our after-sales department to apply for return or replacement. The after-sales staff will respond within 24 hours, confirm the problem through photos, videos, or on-site inspection, and handle it according to the actual situation.
We provide technical support services, including answering customers' questions about product installation, use, and maintenance. Our technical team can provide installation guidance and technical training for customers, and formulate personalized grounding solutions according to the customer's specific application scenarios to ensure the safe and effective use of the products.
We also carry out regular follow-up services for customers, understand the use of the products, collect customer feedback and suggestions, and continuously improve the product quality and service level. For major projects, we can send technical personnel to the site for inspection and maintenance during the construction and use process to ensure the smooth progress of the project.
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