Power cable (a type of electrical cable) is an assembly of two or more conductors held together and typically covered with an overall sheath. The conductors may be of the same or different sizes, each with their own insulation and possibly a bare conductor. A hybrid cable may also include non-electrical conductors (such as fiber optics), electrical power conductors, data signalling or control conductors, and radio frequency conductors (such as coaxial cable). The sheath may be of metal, plastic, ceramic, and may also contain structural supports such as kevlar or other high-strength materials.

Common types of general-purpose cables used by electricians are defined in the National Electrical Code or other national standards and are generally defined according to the conductors and the materials used, shape, and intended usage for the sheath. A sheath may be metallic, mineral, non-metallic, shielded, sunlight-resistant, fire-retardant, flat or round. The conductors may be copper, aluminum, stranded, solid, and of various diameters as determined by the required ampacity of the application. As mentioned, they may be individually insulated or bare. There may also be one or more conductive sheaths for reducing radio-frequency penetration of the sheath.

For example, Type UF (underground feeder) is a non-metallic, flame-retardant sheath containing conductors having moisture-resistant insulation suitable for direct burial in the earth or in concrete. Type AC is a "metal clad" cable assembly made by twisting an interlocking metal table or other metallic sheath around conductors. A common name is BX, after an early genericized trademark of the General Electric company.

The common "lamp cord" is a type of power cable having two separately insulated power conductors, often molded together into a flat cord. There may also be a third (grounding) conductor, in which case the cord may be flat or round. Cords are classed according to the strength and other chemical properties of the sheath and insulation, such as waterproof, heavy-duty, oil-resistant, or high-temperature. National standards determine what types of cords are acceptable for specific devices or uses (e.g., high-temperature cords for portable heating devices; heavy-duty cords for commercial vacuum cleaners).

A "cord set" is a standardized power cable with suitable connectors for connecting the conductors temporarily to other cables or devices, as where a portable appliance is connected to mains voltage through a power cord or an extension cord.

Electrical power cables should be distinguished from electrical conduit, which may also contain one or more conductors, but is not a factory assembly of conductors held together, but rather just a sheath. Conduit may also be rigid or flexible, metallic or non-metallic, and differentiation from cable may require some investigation of the contents within the sheath or how the conductors are terminated in connectors. By comparison, most conduits are arranged so that their contents may be "pulled" or removed from one end of the conduit, whereas conductors in cables are fastened to each other and must be removed together. Cable is often installed in conduit for additional protection from physical damage, adding yet another level of complication.