— A Comparative Selection Guide

In industrial automation projects, instrumentation cables serve as the lifeline for signal transmission. A common and critical question during cable selection is: Do I need armor?

Armor refers to a metallic protective layer added between the inner sheath (or directly over the cable core) and the outer sheath. This “metal armor” provides enhanced mechanical protection but also brings changes in cost, weight, and flexibility. This article will help you make the right choice from the perspectives of construction, performance, application scenarios, and cost.

With nearly five decades of experience in manufacturing instrumentation cables, Anhui Tiankang (Group) Co., Ltd. offers a full range of armored and unarmored products, widely used in oil & gas, chemical, power, metallurgy, and other industries.

1. What Are Armored and Unarmored Instrumentation Cables?

Armor position is typically between the inner sheath (or directly on the cable core) and the outer sheath. Common armor types:

• Steel tape armor : Double-layer galvanized steel tape wrap. Good compressive and impact resistance, rodent/termite protection. Suitable for direct burial or fixed installation.

• Steel wire armor : Galvanized steel wire braid or spiral. High tensile strength. Suitable for vertical runs or applications requiring pulling strength (e.g., shafts, offshore platforms).

• Aluminum tape armor : Lighter, but mechanical strength is lower than steel tape; used for specific lightweight requirements.

2. Core Differences Between Armored and Unarmored Cables

3. Three Core Advantages of Armored Cables

1. Superior mechanical protection
   The armor effectively resists external damage: construction crushing, impact from falling rocks, accidental digging, rodent/termite chewing. In direct burial applications, armored cables do not require additional protective conduits.

2. Rodent and termite resistance, extended service life
   In areas with high rodent/termite activity—such as remote oilfields, chemical plants—ordinary PVC sheaths are easily chewed through, leading to insulation moisture ingress, short circuits, or signal loss. Galvanized steel tape armor is a proven solution.

3. Reduced installation materials and labor
   For direct burial or outdoor exposed routes, armored cables eliminate the need for metal conduit or concrete troughs, significantly reducing material cost and installation time. In hazardous areas, armored cables with appropriate cable glands meet code requirements.

4. Three Core Advantages of Unarmored Cables

1. Good flexibility, easy installation
   Unarmored cables can easily pass through narrow cable trays, bent conduits, or be laid in a serpentine pattern. They are also easier to terminate inside crowded cabinets.

2. Light weight and lower cost
   For the same number of cores and conductor size, unarmored cables are 30–50 % lighter and 20–40 % lower in cost. For long runs or large quantities, the savings are substantial.

3. Higher installation efficiency
   Cutting, stripping, and terminating unarmored cables is easier and requires no special tools for armor handling. This is especially beneficial for frequent wiring or temporary projects.

5. How to Choose: Decision Framework and Scenario Mapping

Key Decision Questions

1. Installation method : Direct burial → armor required (unless you use metal conduit, but direct burial typically does not use conduit).
   Cable tray or conduit → unarmored is usually sufficient.

2. Environmental risks : Rodents, falling rocks, risk of mechanical digging? If yes → armor.
   Tensile or vertical hanging risk? If yes → steel wire armor.

3. Hazardous area requirements : For exposed cables in hazardous areas, armor or metal conduit is recommended. Armor can replace conduit.

4. Budget and schedule : Unarmored has lower material cost and faster installation. Armored total cost must be evaluated (material + installation + grounding).

Typical Scenario Selection Guide

6. Tiankang Armored and Unarmored Instrumentation Cable Features

Anhui Tiankang offers a full range of instrumentation cables with optional armor constructions.

Unarmored Instrumentation Cables

• Conductor : 0.5/0.75/1.0/1.5 mm² copper or tinned copper

• Insulation : PE, XLPE, PVC, fluoroplastic

• Shielding : Aluminum foil + drain wire / copper wire braid / individual + overall shield

• Sheath : PVC, oil‑resistant PVC, LSZH, PE

• Applications : Trays, conduit, indoor

Armored Instrumentation Cables

• Adds armor to the unarmored construction :

• Steel tape armor : Double‑layer 0.2 mm galvanized steel tape; for direct burial, rodent/termite protection

• Steel wire armor : Galvanized steel wire braid or spiral; for tensile strength, vertical installation

• Outer sheath : PVC, PE, LSZH (oil‑resistant grades available)

• Applications : Direct burial, outdoor exposed, hazardous areas, offshore platforms

Quality Assurance

• CNAS‑accredited laboratory for mechanical, electrical, flame, and fire resistance tests

• ISO 9001, ISO 14001, GJB 9001B certified

• Compliant with GB/T 9330, GB/T 19666, and IEC standards

• Custom armor constructions available per customer drawings

7. Common Misunderstandings Clarified

❌ Myth 1: Armored cables do not need shielding
✅ Fact: The armor provides some electromagnetic shielding, but its primary function is mechanical protection. For analog signals, a dedicated copper braid or foil shield is still required.

❌ Myth 2: Armored cables must be grounded at both ends
✅ Fact: Grounding depends on the purpose. For mechanical protection, single‑end grounding is usually sufficient to avoid circulating currents. For auxiliary shielding, follow code requirements. Always refer to the design drawings and electrical codes.

❌ Myth 3: Unarmored cables cannot be used in hazardous areas
✅ Fact: Unarmored cables can be used in hazardous areas if installed in metal conduit. Armor is one of several compliant methods, offering convenience.

❌ Myth 4: All armor types resist rodents and termites
✅ Fact: Only steel tape or steel wire armor effectively resists rodents and termites. Aluminum tape armor has lower mechanical strength and may be chewed through.

8. Conclusion and Recommendations

• Choose unarmored when : Cables are installed in trays, conduit, or indoors with no risk of rodent attack or mechanical damage. Unarmored is economical and flexible.

• Choose armored when : Direct burial, exposed installation, rodent/termite infestation, hazardous area exposed runs (to save conduit costs), vertical high‑drop scenarios. Armor provides irreplaceable protection.

• Compromise solution : Some projects use “partial armor”—adding flexible metal conduit protection only in vulnerable sections (e.g., rising from ground, wall penetrations) while using unarmored elsewhere. Tiankang can support such arrangements.

The final selection should be based on project‑specific conditions, code requirements, and total life‑cycle cost assessment. Anhui Tiankang, with nearly five decades of industry experience, provides professional technical support and customized products.

For project‑specific instrumentation cable selection advice or quotations, please email [email protected] or visit http://www.tiankang-global.com/. The Tiankang Electrical Engineering Technology Department is ready to assist you.