In cable construction, a belt is one or more uniform insulation layers surrounding conductors to improve electrical insulation and structural integrity.
Belted-type cable construction involves individually insulated conductors collectively wrapped in additional insulating layers known as belts. These belts may be made of rubber, paper, or synthetic polymers and provide added dielectric strength, mechanical protection, and separation from the cable sheath. In multi-conductor designs, the belt helps prevent electrical discharge between conductors and ground while serving as a buffer against physical stress. Though largely replaced by modern shielded and compact designs, belted construction remains relevant in some low- to medium-voltage applications.
Belted-type cable constructions may fall under UL (Underwriters Laboratories) and the National Electrical Code (NEC) in commercial and industrial power systems.
The belted cable method emerged in the early 20th century when advanced insulating materials were not yet available. Layers of paper or rubber provided the necessary dielectric strength and moisture resistance. Although less common today, the term persists in cable manufacturing to describe this legacy approach.