What is armoring in optical cables

Armored optical cables are reinforced fiber optic cables designed to protect delicate fibers from physical damage, environmental hazards, and mechanical stress, ensuring long-term reliability in harsh conditions.

Purpose of Armoring

Armoring is applied to optical cables to enhance mechanical strength and durability, protecting the internal fibers from crushing, bending, rodent attacks, moisture, and other environmental hazards. This makes armored cables ideal for underground conduits, direct burial, industrial sites, and high-traffic areas, while non-armored cables are more suitable for standard indoor applications.

Construction of Armored Cables

A typical armored fiber optic cable consists of multiple layers: Optical Fibers: Single-mode or multi-mode fibers that transmit data via light signals. Strength Members: Materials like aramid yarns (e.g., Kevlar), steel wires, or FRP rods provide tensile strength and prevent stretching or breaking. Armoring Layer: This can be steel tape (STA), steel wires (SWA), or interlocking/spiral metal strips.

The armor protects against crushing, impact, and rodent damage, and may be single or double-layered for extra protection in high-risk environments. Outer Jacket: Made of polyethylene (PE), PVC, or LSZH materials, the jacket provides weather resistance, abrasion protection, and fire safety. Some armored cables also include rip cords under the armor for easier jacket removal during splicing or termination.

Types of Armoring

Steel Tape Armored (STA): Corrugated steel tape wrapped around the fiber bundle, offering radial compression resistance. Steel Wire Armored (SWA): Layers of steel wires providing superior tensile and impact resistance, often used in outdoor or industrial installations. Interlock Armor: Interlocking metal strips that enhance tensile strength and crush resistance, suitable for frequent cable movement.

Square-

Lock Armor: Square-profiled metal strips providing flexibility and bending resistance. Double Armored: Combines tape and wire layers for extreme protection, commonly used in submarine or mining applications.

Benefits

Mechanical Protection: Resists crushing, bending, and impact. Rodent Resistance: Prevents damage from pests. Environmental Resistance: Protects against moisture, UV radiation, and chemicals.

Longevity: Armored cables can provide 20–30 years of reliable service in harsh environments. Versatility: Suitable for indoor, outdoor, aerial, and direct burial installations.

Grounding Considerations

Metallic armored cables require proper bonding and grounding at splice closures, manholes, pedestals, or building entrances to ensure safety and compliance with electrical codes. All-dielectric armored cables, which lack conductive components, do not require grounding.

Applications

Armored optical cables are widely used in: Telecommunications networksIndustrial and mining environmentsData centers and medical facilitiesOutdoor and direct burial installationsHigh-traffic or rodent-prone areas Understanding the structure, types, and benefits of armored optical cables helps ensure long-term network stability, protection, and performance in demanding environments.