AbstractThis paper describes the optical cord and stranded cable used in cable transmission systems, stations or relays. The allowable stress, bending radius and lateral load of the fiber core are explained first, and then component designs are presented that ensure these characteristics. Tensile strength requirements on the optical cable necessitate using a cord of more than 5,500 denier and a central steel wire with 1‐mm radius. On the basis of the deformation of the PVC sheath due to lateral load, the standard outer diameter of the cable is determined to be 3 mm. The buckling phenomenon of nylon pipe is discussed as it applies to a tube‐type cord, and it is shown that the Young's modulus of the pipe must be below 70 Kg/mm2. The transmission properties, strain, tensile and bending properties of cords and cables, fabricated on the basis of the above‐described design satisfy the desired objectives, confirming the effectiveness of the d