Several common cable outer sheath materials are PVC, PE, LSZH, AT and rodent-proof sheath materials. Whether you are designing and manufacturing a new cable or simply choosing an existing one for data, power, fiber optics, or industrial automation, the outer sheath (jacket) is much more than just a speaking cover to the eye; it is, in fact, an important job holder in mechanical protection. cable placement. Sheath issues discussed: single jacket versus dual jacket, armored versus unarmored, and metallic versus di lectric. What Is a Cable Sheath and Why It Matters 🔍 The cable sheath is the outer protective layer of a fiber optic cable. Keep ambient or stray light from creating signal noise (for sensor applications). Glass fiber and plastic fiber is fragile.