When talking about electrical cables, many people focus on conductors, insulation, or voltage ratings. However, in many installations, there is another critical component that ensures safety and long-term reliability: armoring.
Armoring is a layer of metallic protection—usually steel tape, steel wire, or aluminum—applied over the insulated core of a cable and beneath the outer sheath. Its role extends beyond simple protection. It is a design choice that determines whether a cable can withstand harsh conditions such as mechanical impact, underground installation, corrosive environments, or even rodent attacks.
This article will explore the purpose of armoring in cables, covering how it works, its different types, and why certain environments absolutely require it.
1. The Core Purpose of Cable Armoring
1.1 Mechanical Protection
Armoring primarily protects cables against mechanical damage. During installation, transport, or operation, cables can be subjected to crushing, bending, and impacts from rocks or tools. The armor absorbs these stresses, ensuring the insulation and conductor remain intact.
1.2 Tensile Strength
For long runs—especially vertical or suspended installations—cables are exposed to tensile forces. Steel Wire Armored (SWA) cables are specifically designed to handle these longitudinal stresses, preventing conductor stretching or insulation cracking.
1.3 Resistance to Rodents and Termites
In certain regions, rodents and termites pose a serious threat to cable sheaths. Armoring provides a physical barrier, preventing these animals from biting into the insulation and causing failures.
1.4 Prolonged Service Life
By reducing the risk of mechanical and environmental damage, armoring extends the operational life of cables, lowering replacement and maintenance costs.
2. Common Types of Cable Armoring
Different engineering environments require different forms of armoring:
2.1 Steel Tape Armored (STA)
Constructed from overlapping layers of galvanized steel tape.
Provides excellent resistance to compression and external impact.
Less flexible compared to wire armoring.
Common in underground installations, tunnels, and building distribution systems.
2.2 Steel Wire Armored (SWA)
Made of multiple galvanized steel wires applied helically around the cable.
Offers both mechanical protection and high tensile strength.
Suitable for vertical shafts, cable trays, and outdoor applications.
Widely used in power distribution and industrial environments.
2.3 Aluminum Wire/Tape Armored
Designed for aluminum conductor cables to prevent galvanic corrosion.
Lightweight, resistant to corrosion, and used in areas where weight is a concern.
2.4 Stainless Steel Armored
Provides superior corrosion resistance, even in highly aggressive chemical or marine environments.
Higher cost, typically reserved for offshore platforms and chemical plants.
3. Why Some Cables Must Be Armored
Not all cables require armoring, but in specific applications, it is essential.
3.1 Underground Installations
Buried cables are exposed to rocks, soil pressure, and accidental excavation. Armoring prevents insulation breaches that could lead to faults.
3.2 High-Voltage Power Transmission
High-voltage XLPE cables are heavy and rigid. During laying and operation, armor prevents bending stress and ensures long-term stability.
3.3 Harsh Industrial Environments
Factories, ports, and mining areas expose cables to vibration, machinery, and physical impacts. Armoring guarantees reliable operation with minimal downtime.
3.4 Offshore and Submarine Cables
Submarine and offshore cables require robust armoring to withstand seabed pressure, ocean currents, ship anchors, and marine life. Often, multi-layer armor designs are used for maximum protection.
4. Armored vs. Non-Armored Cables
Feature Armored Cable Non-Armored Cable
Mechanical Strength High Low
Service Life Longer Shorter
Installation Suitable for underground and outdoor Mainly indoor and low-risk areas
Cost Higher Lower
Typical Applications Power transmission, industrial plants, mining, offshore Residential wiring, indoor distribution
5. Standards and Regulations for Armored Cables
To ensure safety and performance, armored cables are manufactured in accordance with strict standards:
IEC 60502: International standard covering power cables with extruded insulation and their armoring requirements.
BS 5467: British Standard specifying low-voltage SWA cables for fixed installations.
IEEE & NEC: American standards that provide guidance on the application of armored cables in industrial environments.
Compliance with these standards is crucial for safety, quality, and international trade.
6. Applications of Armored Cables
Armored cables are used across multiple industries, including:
Construction: STA cables for underground distribution in residential and commercial buildings.
Mining: SWA cables designed to withstand crushing forces from heavy machinery.
Oil & Gas: Stainless steel armored cables for offshore rigs exposed to saltwater.
Renewable Energy: Armored XLPE cables in wind farms and solar parks to ensure long-term reliability.
7. Conclusion
Armoring in cables is not just an extra metallic layer—it is a vital feature that ensures:
Mechanical protection from external impact
Resistance to tensile forces
Protection against rodents and environmental hazards
Longevity and reduced maintenance costs
When selecting a cable, engineers must consider whether the application environment justifies the need for armoring. In underground, industrial, or offshore projects, armored cables are often the only reliable solution to guarantee performance and safety.
