電纜主要由以下4部分組成。①導電線芯：用高電導率材料（銅或鋁）制成。根據敷設使用條件對電纜柔軟程度的要求，每根線心可能由單根導線或多根導線絞合而成。②絕緣層：用作電纜的絕緣材料應當具有高的絕緣電阻，高的擊穿電場強度，低的介質損耗和低的介電常數。電纜中常用的絕緣材料有油浸紙、聚氯乙烯、聚乙烯、交聯聚乙烯、橡皮等。電纜常以絕緣材料分類，例如油浸紙絕緣電纜、聚氯乙烯電纜、交聯聚乙烯電纜等。③密封護套：保護絕緣線心免受機械、水分、潮氣、化學物品、光等的損傷。對于易受潮的絕緣，一般采用鉛或鋁擠壓密封護套。④保護覆蓋層：用以保護密封護套免受機械損傷。一般采用鍍鋅鋼帶、鋼絲或銅帶、銅絲等作為鎧甲包繞在護套外（稱鎧裝電纜），鎧裝層同時起電場屏蔽和防止外界電磁波干擾的作用。為了避免鋼帶、鋼絲受周圍媒質的腐蝕，一般在它們外面涂以瀝青或包繞浸漬黃麻層或擠壓聚乙烯、聚氯乙烯套。
The cable mainly consists of the following four parts. Conductive wire core: made of high conductivity material (copper or aluminium). According to the requirements of laying conditions for cable flexibility, each wire core may be made of a single wire or multiple wires. (2) Insulation layer: The insulation material used for cable should have high insulation resistance, high breakdown electric field strength, low dielectric loss and low dielectric constant. The common insulating materials used in cables are oil-impregnated paper, polyvinyl chloride, polyethylene, cross-linked polyethylene, rubber and so on. Cables are often classified as insulation materials, such as oil-immersed paper insulated cables, polyvinyl chloride cables, cross-linked polyethylene cables, etc. (3) Sealing sheath: Protect insulating wire core from mechanical, moisture, moisture, chemicals, light and other damage. Lead or aluminium extrusion sealing sheaths are generally used for moisture-prone insulation. (4) Protection Cover: To protect the sealing sheath from mechanical damage. Generally, galvanized steel strip, steel wire or copper strip, copper wire, etc. are used as armor to wrap around the sheath (called armored cable). The armor layer plays the role of electric field shielding and electromagnetic interference prevention. In order to avoid the corrosion of steel strips and steel wires by surrounding media, they are usually coated with asphalt or wrapped with impregnated jute or extruded with polyethylene and polyvinyl chloride.
電纜按其用途可分為電力電纜、通信電纜和控制電纜等。與架空線相比,電纜的優點是線間絕緣距離小,占地空間小，地下敷設而不占地面以上空間，不受周圍環境污染影響，送電可靠性高，對人身安全和周圍環境干擾小。但造價高，施工、檢修均較麻煩，制造也較復雜。因此，電纜多應用于人口密集和電網稠密區及交通擁擠繁忙處；在過江、過河、海底敷設則可避免使用大跨度架空線。在需要避免架空線對通信干擾的地方以及需要考慮美觀或避免暴露目標的場合也可采用電纜。
Cables can be divided into power cables, communication cables and control cables according to their uses. Compared with overhead lines, the advantages of cables are small insulation distance between lines, small space occupied, underground laying without occupying space above the ground, not affected by environmental pollution, high reliability of power transmission, and less interference to personal safety and the surrounding environment. But the cost is high, the construction and maintenance are more troublesome, and the manufacture is more complicated. Therefore, cables are mostly used in densely populated areas, densely populated power grids and traffic congestion areas; large-span overhead lines can be avoided in laying across rivers, rivers and seabed. Cables can also be used in places where interference from overhead lines to communications needs to be avoided and where aesthetic considerations or exposure of objects need to be considered.