Medium Voltage Unarmoured Cable: Applications, Installation, and Selection Guide

Medium voltage unarmoured cable is a power cable without a metallic armour layer, intended for medium voltage distribution where the installation provides adequate mechanical protection. It is commonly considered for indoor electrical networks, cable trays, and ducts, but it is not automatically suitable for direct burial or locations exposed to impact. The right choice depends on the system voltage, load, installation environment, fault requirements, and applicable project standard. This guide explains how to match cable construction to an application, plan installation, and assess suppliers before purchasing.

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Key Takeaways

• Choose unarmoured construction only when the route and installation method provide appropriate protection against mechanical damage.
• Confirm voltage designation, conductor material and size, insulation, screen, sheath, and required testing in the project specification.
• Review the entire cable route, including ducts, trays, joints, terminations, and environmental exposure, before approving a design.
• Request a project-specific quotation that identifies technical assumptions, quantity, delivery terms, and any required documentation.

Who This Guide Is For

This guide is for electrical consultants, EPC contractors, utility and industrial procurement teams, panel builders, and distributors evaluating medium voltage unarmoured cable. It is also useful for buyers preparing a request for quotation or reviewing whether an existing cable specification fits a proposed route. It provides practical selection guidance, not a substitute for engineering calculations or local electrical requirements. Final cable approval should be made by the responsible project engineer.

Understanding Medium Voltage Unarmoured Cable

Basic construction and function

A typical medium voltage cable includes a conductor, conductor screen, insulation, insulation screen, metallic screen, and outer sheath. The conductor carries electrical current, while the insulation and semiconductive screens form part of the voltage-control system. The metallic screen provides an electrical path for fault current and grounding when designed and connected for that purpose. An unarmoured construction omits the metallic armour normally used as an additional mechanical protection layer.

Unarmoured does not mean unprotected. Protection may come from a building structure, a suitable conduit or duct, a guarded cable tray, or another route design approved for the site. The outer sheath protects against specified environmental exposures, but it should not be treated as a replacement for armour where impact or crushing protection is required. Always check the cable design and installation conditions together.

Voltage and specification context

Medium voltage classifications and cable designations vary by market and project standard. For example, 6/10 kV and 8.7/15 kV are voltage designations used in some cable specifications; they should be selected only after confirming the system voltage, earthing arrangement, and applicable standard. A familiar voltage label by itself does not establish that a cable is suitable for a particular network. Ask the design engineer and supplier to confirm the required U₀, U, and Um values where the governing specification uses them.

Applications and Route Matching

Where unarmoured construction may be suitable

Potential applications include indoor substations, industrial facilities, power plants, and commercial infrastructure where cables are routed in protected spaces. Ducted or enclosed routes may also be considered when the duct system and installation design address foreseeable mechanical hazards. Cable trays can be suitable where the route is controlled and the project specification permits unarmoured cable. The suitability of each application depends on local codes, site risks, and the cable manufacturer’s declared design.

Where additional protection may be needed

Direct-buried routes, exposed outdoor runs, areas subject to vehicle movement, and locations with a credible risk of impact need careful review. A project may require armoured cable, a protective conduit, concrete encasement, barriers, or another engineered solution. Moisture, chemicals, ultraviolet exposure, and temperature can also affect sheath selection and service suitability. Do not choose an unarmoured cable solely to reduce purchase cost without evaluating the installed route and protection requirements.

Materials and Key Specifications

Conductor material is commonly copper or aluminium, subject to project requirements and system design. Copper and aluminium differ in electrical and mechanical properties, so conductor size should be selected through load, voltage-drop, short-circuit, and installation calculations rather than by substituting one material for another at the same nominal size. XLPE insulation is used in many medium voltage designs, while other insulation systems may be required by a particular specification or operating environment. Confirm the complete construction rather than relying on a brief product name.

Selection Framework for Buyers

1. Define the electrical duty

Provide the nominal system voltage, load current, installation conditions, fault level, protection-clearing time, and earthing arrangement to the design team or supplier. These details support conductor sizing and screen design, but final calculations must follow the project’s engineering rules. Also identify whether the route includes parallel cables or special installation conditions that affect current-carrying capacity. Incomplete electrical inputs can lead to quotations based on assumptions that do not match the project.

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2. Describe the complete route

State whether the cable will be installed in a tray, conduit, duct, tunnel, building space, or another arrangement. Include indoor and outdoor sections, exposure to water or chemicals, expected mechanical hazards, and any fire-performance requirements. Ask the engineering team to confirm how bends, pulling tension, supports, and separation from other services will be managed. Installation limits should come from the approved cable data and project method statement, not from a generic rule.

3. Align construction and compliance requirements

List the required cable standard, conductor and insulation materials, screen configuration, sheath requirements, markings, and inspection documents in the RFQ. If a standard such as IEC 60502-2 is specified, confirm the relevant edition and any project-specific amendments with the engineer and supplier. Do not assume that a supplier’s general product description proves compliance with every clause. Request written confirmation against the exact construction and standard requested.

Installation Considerations

Before installation, inspect the delivery reels and cable markings against the approved purchase documents. Check that the route is ready, ducts are clear, trays and supports are suitable, and the planned pulling method is compatible with the cable design. Use the manufacturer’s stated minimum bending radius and maximum pulling limits for the specific cable rather than applying values from another design. Protect cable ends from water and contamination during storage and handling.

During installation, avoid dragging cable over sharp edges or allowing uncontrolled twisting and kinking. Coordinate pulling equipment, rollers, lubrication where permitted, and communication between crews to reduce the risk of sheath or insulation damage. After installation, complete the inspections and electrical tests required by the applicable standard and project quality plan. Keep test records, route drawings, reel identifiers, and termination details together for handover.

Pricing, MOQ, and Lead Time

The price of medium voltage unarmoured cable depends on the requested voltage class, conductor material and size, insulation and sheath construction, screen design, order quantity, and delivery destination. Reel lengths, packaging, testing scope, copper or aluminium market movements, and shipping arrangements may also affect the quotation. Minimum order quantity and production lead time are supplier- and specification-dependent, so buyers should request confirmation for the exact bill of materials. Avoid comparing offers on price alone when the included construction or documentation differs.

For a more comparable quotation, provide the cable schedule, applicable standard, required quantity, preferred reel length, delivery location, and target delivery window. Ask suppliers to identify exclusions, technical deviations, quotation validity, and whether the stated lead time begins after approval of drawings or specifications. If a project is still at design stage, mark provisional details clearly to prevent assumptions from being treated as final requirements. Zhongdong Cable Co., Ltd. can review an inquiry and discuss the requested cable construction, documentation, and supply requirements with the buyer.

Supplier Evaluation Checklist

• Can the supplier confirm the proposed design against the exact voltage rating and project specification?
• Does the quotation clearly state conductor, insulation, screens, sheath, and reel details?
• Can the supplier explain which routine or acceptance tests and documents are included?
• Are deviations, assumptions, MOQ, lead time, and delivery terms stated in writing?
• Is there a clear process for resolving technical questions and reviewing changes before production?

Ask for product data and supporting documents relevant to the specific order, and have the project engineer review them before approval. Where a requirement is not confirmed, request clarification rather than inferring compliance from a catalogue description. This approach helps procurement compare technically equivalent offers and reduces avoidable changes later in the project.

Conclusion and Next Steps

Medium voltage unarmoured cable can be a suitable choice when the electrical design is correct and the route provides the mechanical protection the application requires. It should not be selected on voltage rating or initial price alone; construction, installation conditions, standards, and project documentation all matter. Start by documenting the electrical duty and full cable route, then obtain engineering confirmation of the required design. Share that specification with Zhongdong Cable Co., Ltd. to discuss a project-specific quotation and clarify supply details before placing an order.

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