The multi-core 16, 25, 35, 50, 70, 95, 120mm² Nyy N2xy underground low voltage copper core power cables are a series designed specifically for underground low-voltage distribution systems. They are widely used in underground power transmission scenarios such as urban power grids, residential communities, industrial parks, and municipal engineering. This series of cables features high-purity copper cores as conductors, combined with multi-layer insulation and protective structures, offering excellent conductivity, mechanical strength, and environmental adaptability to meet the underground power transmission needs of different load intensities.​ In terms of specifications, the series provides seven cross-sectional areas: 16mm², 25mm², 35mm², 50mm², 70mm², 95mm², and 120mm², covering a wide range of applications from low to medium-high loads. The 16mm² and 25mm² cables are suitable for small user branch lines, courtyard lighting, and small commercial facilities; 35mm² and 50mm² can meet the main incoming line requirements of multi-storey residences and medium-sized commercial buildings; 70mm² to 120mm² are applicable to trunk lines in industrial parks, large communities, and important power transmission in municipal engineering. The two models (Nyy and N2xy) differ slightly in structure: Nyy cables use polyvinyl chloride (PVC) insulation and PVC sheaths, which are cost-effective and flexible for installation; N2xy cables adopt cross-linked polyethylene (XLPE) insulation and PVC sheaths, featuring higher heat resistance and aging resistance, suitable for environments with more stringent performance requirements.​ In structural design, all cables use multi-core copper conductors with a purity of over 99.95%. After annealing treatment, they have excellent conductivity and flexibility, ensuring low resistance and efficient power transmission. Regarding the insulation layer, the PVC insulation of Nyy allows a long-term operating temperature of 70℃ and can withstand 160℃ during short circuits (within 5 seconds); the XLPE insulation of N2xy has a long-term operating temperature of up to 90℃ and a short-circuit withstand temperature of 250℃, maintaining stable performance in higher temperature environments. The core is wrapped with a filling layer and wrapping tape to enhance structural stability and prevent internal wear; the outermost layer is a PVC sheath, which has properties such as acid and alkali resistance, corrosion resistance, and mechanical impact resistance. It can resist moisture, impurities in underground soil, and damage from rodents, protecting the internal structure from harm.​ In terms of performance, the series of cables has a rated voltage of 0.6/1kV, meeting the standards of low-voltage distribution systems and suitable for AC 50Hz/60Hz circuits. The current-carrying capacity increases with the cross-sectional area: 16mm² has a current-carrying capacity of approximately 80-100A when laid in air, while 120mm² can reach 250-280A, meeting the load requirements of different scenarios. The insulation resistance exceeds 1000MΩ·km, and the dielectric loss tangent (tanδ) is less than 0.005, ensuring efficient power transmission and reducing energy loss. In terms of mechanical properties, the minimum bending radius is 12 times the cable outer diameter (for fixed laying) and 20 times the outer diameter (for dynamic laying), facilitating installation in narrow underground spaces; the sheath has a tensile strength of ≥12MPa and an elongation rate of ≥150%, capable of withstanding stretching and extrusion during laying.​ In application scenarios, Nyy cables are often used in ordinary residential communities, small industrial parks, and underground power distribution in non-harsh environments due to their economy; N2xy cables, due to the advantages of XLPE insulation, are suitable for areas with high temperatures, humidity, or high chemical corrosion risks, such as around chemical plants, underground parking lots, and sewage treatment plants. Specifically, 16-35mm² cables can be used to connect user electric meters, street lights, and small equipment; 50-70mm² are applicable to building distribution trunk lines and medium-sized factory branch lines; 95-120mm² serve as regional trunk lines, connecting transformers and distribution rooms to support centralized power supply in large communities or industrial parks.​ In terms of installation and maintenance, the cables support underground laying methods such as direct burial, pipe laying, and trench laying. For direct burial, they must be buried below the frozen soil layer and keep a safe distance from other underground facilities. Before laying, check whether the cable appearance is damaged; during laying, avoid excessive bending or dragging to prevent damage to the insulation layer and sheath. Use special copper joints for connection to ensure conductivity and sealing effect, preventing moisture intrusion. After installation, insulation resistance testing and voltage withstand testing must be carried out to confirm that the performance meets the standards. In daily maintenance, locate the cable path through ground signs to avoid accidental damage during construction; regularly inspect the soil environment and take anti-corrosion measures in areas with high corrosion risks to extend the cable service life.​ In conclusion, the multi-core 16-120mm² Nyy N2xy underground low voltage copper core power cables, with their rich specification options, reliable structural design, and excellent comprehensive performance, have become an ideal solution for underground low-voltage distribution systems. They can flexibly match different load requirements and maintain stable operation in complex underground environments, providing a solid guarantee for the safe and efficient transmission of underground power networks.