Useless wires inside optical cables

The "wires" inside optical cables are not useless; they serve protective, structural, and grounding purposes.

Structural Reinforcement

Optical fibers are extremely thin, often the diameter of a human hair, and are fragile. To protect them from mechanical stress, bending, and crushing, cables include additional layers such as plastic coatings, resin buffers, and sometimes steel or metallic wires. In submarine cables, for example, steel wires are wrapped around the fiber core to provide tensile strength, allowing the cable to withstand ocean currents, seabed friction, and the weight of long cable spans without breaking the delicate glass fibers .

Protection Against Environmental Damage

These wires also help protect the fibers from environmental hazards. In terrestrial installations, metallic elements can shield fibers from rodents, accidental cuts, or heavy loads. In undersea cables, armoring layers with steel wires prevent damage from anchors, fishing equipment, and natural seabed movements .

Grounding and Electrical Safety

Some optical cables include metallic wires for grounding purposes. While the fibers themselves carry light and are electrically inert, the metallic components can provide a path for electrical grounding, which is important in hybrid cables that may include power conductors for repeaters or amplifiers in long-distance systems .

Summary

Although optical fibers transmit data using light, the additional wires inside the cable are essential for durability, mechanical strength, and safety. They ensure the cable can survive installation, environmental stress, and long-term operation, especially in challenging environments like undersea or industrial settings. Without these protective wires, the fragile fibers would be prone to breakage, signal loss, or complete failure .