Armored Cable Guide Selection Installation and Safety Tips

Imagine a sudden downpour, an accidental excavation, or even routine wear and tear—any of these could deal a fatal blow to vulnerable power lines. How can we ensure safe, stable, and enduring power transmission? The answer lies in those seemingly unremarkable armored cables. Like silent steel sentinels of our electrical systems, they vigilantly safeguard our daily lives and work. This comprehensive guide explores the world of armored cables, from selection to installation, application to maintenance, helping you build an impregnable defense for electrical safety.

Armored Cables: The Sturdy Backbone of Electrical Safety

Armored cables have become indispensable components in modern electrical installations. They provide exceptional protection and durability while resisting physical threats and harsh environmental conditions, ensuring secure and reliable power and signal transmission. This guide thoroughly examines all aspects of armored cables to help you confidently address various electrical engineering challenges.

What Are Armored Cables?

Armored cables are specially reinforced power cables featuring a protective metal sheath that effectively guards against physical damage. This robust design makes them ideal for power transmission in high-risk environments, particularly locations prone to mechanical damage.

The most distinctive feature of armored cables is their protective layer, typically made of steel or aluminum, which effectively shields internal conductors from mechanical damage and external pressure. This design grants armored cables extended service life, especially in harsh outdoor environments exposed to moisture, chemical corrosion, and extreme temperatures.

Types and Applications of Armored Cables

Armored cables are not one-size-fits-all; they come in various types tailored to different applications and requirements. Below are several common armored cables and their typical uses:

Steel Wire Armored (SWA) Cables

SWA cables are commonly used in underground power systems, electrical networks, and outdoor lighting installations. Their steel wire armor provides robust protection, allowing direct burial without additional conduits or protective measures. SWA cables are renowned for their exceptional tensile strength and resistance to mechanical damage, withstanding soil pressure, vehicle loads, and other potential physical threats. They are the preferred choice for applications requiring high-strength protection.

Aluminum Wire Armored (AWA) Cables

AWA cables resemble SWA cables but use aluminum armor instead of steel, making them lighter. This weight advantage proves particularly beneficial for long-distance power transmission, reducing installation costs and structural burdens. AWA cables offer excellent mechanical protection and superior corrosion resistance, especially in damp or salt-spray environments. Additionally, aluminum's superior conductivity enhances overall electrical performance.

Steel Tape Armored (STA) Cables

STA cables employ steel tape armor, providing a thinner protective layer. They are typically used in space-constrained indoor and buried applications that still require protection. STA cables offer flexibility and ease of installation, allowing bending and routing in tight spaces. While their mechanical strength doesn't match SWA cables, they adequately handle general physical impacts and pressure. STA cables are also frequently used to protect control and signal cables from external interference.

Each armored cable type serves specific purposes, with suitability determined by environmental conditions, installation type, and project electrical requirements. Selecting the appropriate armored cable is crucial for ensuring safe and reliable electrical system operation.

When Should You Use Armored Cables?

Armored cables are designed for situations where electrical wiring faces elevated risks of mechanical damage, interference, or exposure to harsh environmental conditions. They represent an ideal choice for ensuring safety and longevity in both commercial and residential settings. Below are typical scenarios for armored cable use:

Outdoor Installations

With their robust weatherproofing capabilities, armored cables are perfectly suited for outdoor electrical wiring, including garden lighting, power supplies for outdoor structures, and other external applications. Whether facing scorching heat, freezing cold, wind, or rain, armored cables maintain stable and secure power transmission. Their UV resistance, moisture protection, and corrosion resistance make them ideal for outdoor environments.

Underground Wiring

Armored cables are essential when burying cables underground. Their protective armor safeguards internal wires from moisture, soil corrosion, and physical damage caused by excavation or other ground activities. Underground environments expose cables to multiple threats including soil pH levels, microbial erosion, and mechanical stress. Armored cables effectively resist these threats, ensuring long-term reliable operation of underground power lines.

Areas Prone to Mechanical Damage

In industrial settings or locations where cables may be exposed to potential mechanical damage—such as warehouses, factories, and construction sites—armored cables provide necessary protection to maintain circuit integrity. These environments often contain heavy machinery, sharp objects, and other factors that could damage cables. Armored cables effectively prevent such damage, avoiding power interruptions and safety incidents.

Public or High-Traffic Areas

For safety and durability, armored cables are recommended in public buildings, schools, and hospitals—locations with higher probabilities of interference or physical impact. In these settings, cables may face vandalism, accidental collisions, and other unpredictable factors. Armored cables provide additional protection to ensure safe and reliable electrical system operation.

Armored Cable Sizing

Selecting the correct armored cable size is crucial for electrical installation safety, efficiency, and reliability. Armored cables come in various sizes determined by the cross-sectional area of internal conductors, measured in square millimeters (mm²).

Common Armored Cable Sizes and Typical Uses

• 1.5 mm² and 2.5 mm²: Ideal for lighting circuits and small power tools in residential and commercial environments.
• 4 mm² to 6 mm²: Suitable for larger lighting installations, household power outlets, and outdoor lighting requiring higher current.
• 10 mm² to 16 mm²: Typically used for connecting heavy appliances, small industrial machinery, and large heating units.
• 25 mm² and above: Designed for high-load applications including main power lines, industrial installations, and large electrical machinery.

How to Select the Right Armored Cable Size for Your Project

Choosing the appropriate cable size requires considering the total load of equipment being powered, cable length, and any potential voltage drop over distance. Using a cable size calculator or consulting an electrical engineer can help ensure your selection provides adequate capacity and safety for specific needs. Undersized cables may overheat, cause excessive voltage drop, or even start fires; oversized cables increase costs and installation difficulty. Therefore, precise load and voltage drop calculations are essential.

How Thick Should My Armored Cable Be?

Armored cable thickness is important for ensuring it can handle expected electrical loads without overheating or experiencing excessive voltage drop. Below is guidance for selecting appropriate armored cable thickness:

Calculating Total Load

Sum the power ratings (in watts) of all devices connected to the cable. Convert this to amperes to understand current requirements. Accurate total load calculation is the first step in selecting proper cable thickness. Account for all potentially simultaneous device usage and leave margin for future expansion needs.

Considering Length

For longer runs, choose thicker cables to mitigate voltage drop and ensure efficient power transmission. Longer cables have greater resistance and voltage drop. Therefore, long-distance lines require thicker cables to compensate for voltage drop and ensure devices receive adequate power.

Checking Regulations

Always consult national electrical codes or standards, as they may specify minimum thicknesses for particular applications or environments. Electrical codes are important safety safeguards that must be strictly followed. Codes may vary between countries and regions, so consult local regulations.

Selecting appropriate armored cable thickness addresses not only immediate needs but also ensures electrical installation safety, compliance, and adaptability to future requirements.

Armored Cable Glands

Armored cable glands play important roles in cable installations, serving as interfaces between armored cables and connected equipment or enclosures. These components not only secure cables but also provide necessary sealing and grounding functions.

Cable Glands and Their Role in Armored Cable Installations

Designed to connect and secure armored cable ends to equipment, cable glands offer several advantages:

• Securing Cables: Glands firmly anchor cables, preventing pull-out from systems. Gland designs must withstand certain tension and torque to ensure reliable cable connections.
• Maintaining Integrity: They help maintain enclosure ingress protection ratings, preventing dust, moisture and other environmental contaminants from entering. Glands must provide good sealing to prevent water and dust ingress that could affect equipment operation.
• Grounding and Termination: For armored cables, glands also ensure proper armor grounding and create safe electrical connections with systems. Proper grounding is crucial for electrical safety, preventing shock hazards and equipment damage.

Gland Types and Selecting Appropriate Glands for Your Cable

Choosing correct cable glands is essential for installation safety and effectiveness. Main types include:

• Brass Glands: Durable and corrosion-resistant, suitable for indoor and outdoor applications. Brass offers good conductivity and corrosion resistance, making it ideal for cable glands. Typically used where high strength and corrosion resistance are needed.
• Nylon (Plastic) Glands: Lightweight and suitable for non-hazardous areas, especially where corrosion or metal components are concerns. Nylon provides good insulation and chemical resistance. Typically used where weight and corrosion are considerations.
• Aluminum Glands: Often preferred when using aluminum-armored cables due to material compatibility and corrosion resistance. Aluminum offers good conductivity and corrosion resistance. Typically used where lightweight properties and corrosion resistance are needed.

Selecting appropriate glands requires considering multiple factors including armored cable type, environment (hazardous or non-hazardous), and grounding/sealing requirements.

Armored Cable Installation Tips

Proper armored cable installation is key to electrical system safety and longevity. Below are essential steps and required tools for successful installation.

1. Measurement and Cutting: Precisely measure required cable length and cut using proper tools without damaging internal wires. Use dedicated cable cutters for clean cuts that avoid damaging armor and conductors.
2. Stripping and Preparation: Carefully remove outer sheathing and armor to expose internal conductors without nicking them. Use professional stripping tools for accurate length and depth to avoid insulation damage.
3. Gland Installation: Select appropriate gland size and type, install on cable ends, secure armor and ensure tight sealing. Follow manufacturer instructions for proper fit, grounding and sealing.
4. Conductor Connection: Terminate internal conductors to equipment or enclosures following wiring regulations with secure connections. Use proper terminals and connectors for reliable connections without looseness or poor contact.
5. Securing Glands and Cables: Ensure glands are firmly fixed to equipment, providing secure cable anchoring and proper grounding. Use appropriate tools and fasteners for tight fits with good grounding and support.

Remember—safety is always paramount. Before starting installation, always disconnect power and wear proper protective equipment.

Armored Cable Frequently Asked Questions

What's the difference between SWA and AWA cables?

The primary difference between Steel Wire Armored (SWA) and Aluminum Wire Armored (AWA) cables lies in their armor material. SWA cables use steel wire armor, making them more suitable for applications requiring high mechanical protection. Steel armor provides greater tensile strength and impact resistance for harsher environments.

AWA cables use aluminum wire armor, making them lighter and preferable for installations where weight matters, such as industrial power distribution. While aluminum armor isn't as strong as steel, it offers good corrosion resistance and conductivity for weight-sensitive and conductivity-dependent applications.

Both provide mechanical damage protection, but selection depends on specific installation requirements.

Do all outdoor electrical installations require armored cables?

No, not all outdoor installations require armored cables, but they are strongly recommended for most outdoor applications due to durability and environmental hazard protection. They are particularly suitable for areas exposed to potential mechanical damage or needing extra protection. Outdoor environments expose cables to sunlight, rain, snow, ice, and animal chewing—threats armored cables effectively resist for safe, reliable power system operation.

Can armored cables be used underground?

Yes, armored cables are designed for underground installation. Their sturdy construction protects against moisture, soil corrosion and physical damage, making them safe for direct burial. Underground environments expose cables to soil pH levels, microbial erosion and mechanical stress—threats armored cables effectively resist for long-term reliable underground power line operation.

What are the legal requirements for installing armored cables in the UK?

In the UK, armored cable installations must comply with the Wiring Regulations (BS 7671) covering fixed wiring installations. Installations must be performed by qualified personnel with particular attention to cable protection, underground burial depth, and proper gland and accessory use. UK electrical safety standards are stringent and must be strictly followed for safe, reliable electrical system operation.

How do you cut armored cables?

While several tools can cut armored cables—including side cutters or hacksaws—the best option is dedicated cable cutters specifically designed for this task. Cable cutters feature sharp blades and sturdy construction for cleanly cutting cable armor and internal conductors without damage.

Before cutting, precisely measure required cable length and mark the outer sheath at the cut point. Properly adjust cutter blade depth to cut through the armor. Position the cable in the cutter's wire guide aligned with your marked cut point. Secure it in place and carefully execute the cut.

Do outdoor lights need armored cables?

Armored cables are strongly recommended for outdoor lighting. Outdoor lighting installations face various environmental factors like rain, snow and extreme temperatures that can compromise electrical wiring safety and functionality. Armored cables effectively protect against these elements for safe, reliable outdoor lighting system operation.