In the electrical wiring system of buildings, cables, as the core carriers for power transmission and signal transfer, their performance stability, safety reliability, and adaptability directly affect the overall electrical safety and functional realization of the building. The BVVB series flat sheathed cables have become commonly used wiring products in the construction field due to their unique structural design and excellent performance. Among them, the two specifications of 2×1.5mm² and 2×2.5mm² are widely used in projects such as residential buildings, commercial buildings, and small public facilities because of their wide adaptation scenarios. In terms of product structure, the BVVB cable adopts a three-layer composite structure of "conductor + insulation layer + sheath layer" and has a flat design. This morphological feature brings significant advantages to building wiring. The conductor part is made of high-purity oxygen-free copper, which has an extremely low resistivity (≤0.0172Ω·mm²/m). It can effectively reduce energy consumption and heat generation during current transmission, and at the same time, it has good ductility and corrosion resistance, which can adapt to bending, pulling, and other operations in construction and reduce the risk of conductor breakage. Among them, the cross-sectional area of a single conductor of the 2×1.5mm² specification is 1.5mm², and that of the 2×2.5mm² specification is 2.5mm². Both specifications include two independent conductors, which can meet the needs of live wire and neutral wire transmission in single-phase circuits in buildings without the need for additional neutral wire cables, simplifying the wiring process. The material selection of the insulation layer and sheath layer focuses on safety protection performance. The insulation layer wraps around the outside of a single conductor and is made of polyvinyl chloride (PVC) material with strong temperature resistance and high insulation resistance. Its temperature resistance range can reach -15℃ to 70℃, which can resist temperature fluctuations in the building environment. At the same time, the insulation resistance is ≥100MΩ, which can effectively prevent short circuits or leakage accidents between conductors; the outer sheath is also made of PVC material and optimized through a special formula, with anti-aging, anti-ultraviolet, and wear-resistant properties. It can not only protect the internal conductors and insulation layer from mechanical damage during construction but also isolate moisture, dust, and chemical corrosion in the air, extending the service life of the cable. In addition, the flat sheath design makes it easier for the cable to fit into the gaps of walls, floors, or suspended ceilings, reducing space occupation. It is especially suitable for "concealed laying" scenarios in building decoration (such as wall embedding and under-floor laying), avoiding the impact of cable protrusion on subsequent decoration construction or space aesthetics. In terms of performance parameters and adaptation scenarios, the two specifications of BVVB cables have their own focuses and can be accurately selected according to the electrical needs of the building. The rated current-carrying capacity of the 2×1.5mm² specification cable is 13A (at an ambient temperature of 30℃), with an adapted power of approximately 3kW. It is mainly suitable for low-power electrical scenarios in buildings, such as lighting circuits (ceiling lights, downlights, spotlights, etc., with a single lamp power usually ranging from 10W to 60W and a total circuit power generally not exceeding 2.5kW), small socket circuits (such as bedside sockets in bedrooms and office equipment sockets in studies, connected to devices with power ≤1kW such as laptops and desk lamps), and power supply for weak current equipment (such as routers and surveillance cameras, with power usually ranging from 10W to 50W). Due to its smaller cross-sectional area, this specification cable has better flexibility and is more convenient to lay in narrow spaces (such as the gaps between ceiling keels and wall 穿线管), reducing construction difficulty. The rated current-carrying capacity of the 2×2.5mm² specification cable is 20A (at an ambient temperature of 30℃), with an adapted power of approximately 4.4kW. It is more suitable for medium and high-power electrical scenarios in buildings, such as the main socket circuits in living rooms, kitchens, and bathrooms (connected to home appliances with power ranging from 1kW to 3kW such as refrigerators, washing machines, rice cookers, and electric water heaters), and the power supply circuits for air conditioners (the power of ordinary 1.5-horsepower air conditioners is approximately 1.2kW, and that of 2-horsepower air conditioners is approximately 1.8kW, both within the carrying range of this specification cable). In addition, in the mixed circuits of emergency lighting and ordinary lighting in public areas of buildings (such as corridors and stairwells), since it is necessary to drive multiple lamps at the same time and there may be instantaneous current during emergency power switching, the selection of 2×2.5mm² specification cables can improve the operation stability of the circuit and avoid overload heating. In terms of safety and construction specifications, both BVVB 2×1.5mm² and 2×2.5mm² cables comply with the national standard GB/T 5023-2008 "Polyvinyl Chloride Insulated Cables with Rated Voltage of 450/750V and Below", and have passed multiple tests such as voltage resistance test (AC 3000V/5min without breakdown), insulation aging test, and flame performance test (meeting the "single vertical burning" requirement in GB/T 18380-2008 and having certain flame retardancy), which can meet the basic requirements of building electrical safety. During the construction process, attention should be paid to selecting the appropriate laying method according to the laying environment: when laying concealedly, it is necessary to use galvanized steel pipes or PVC conduit for protection to avoid direct contact between the cable and concrete or cement mortar, which may cause sheath aging; when laying openly, it should be kept away from high-temperature heat sources (such as radiators and water heater exhaust pipes) and sharp objects, and the bending radius should not be less than 6 times the outer diameter of the cable to prevent damage to the insulation layer. At the same time, the long-term operating temperature of both specifications of cables does not exceed 70℃, so during construction, parallel laying with other high-temperature pipelines (such as hot water pipes) should be avoided to reduce the impact of temperature superposition on cable performance. In conclusion, the BVVB 2×1.5mm² and 2×2.5mm² flat sheathed cables have become indispensable products in building wiring due to their reasonable structure, stable performance, and clear adaptation scenarios. In practical applications, it is necessary to scientifically select cable specifications and strictly follow construction specifications based on the functional requirements of building spaces, the power of electrical equipment, and the construction environment, so as to give full play to their performance advantages and ensure the safe and efficient operation of the building electrical system.