Medium Voltage Unarmoured Cable: Construction, Applications, and Selection Guide
Medium voltage unarmoured cable is designed to carry power at medium voltage without a metallic armour layer around its core or cores. It typically includes a conductor, insulation, semiconductive screens, a metallic screen, and an outer sheath, with the exact construction varying by design and applicable standard. We recommend it when the cable route provides suitable mechanical protection and the project specification does not require armour. This guide explains the construction, common applications, and the checks we suggest making before requesting a quotation.
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Who This Guide Is For
We have prepared this guide for electrical contractors, project engineers, distributors, and procurement teams comparing medium voltage cable options. It is intended to support early specification and supplier discussions, not replace an engineering review or the requirements of local electrical codes. Final selection should be confirmed against the network design, installation conditions, and cable manufacturer’s technical documentation.
Understanding Medium Voltage Unarmoured Cable
What “unarmoured” means
“Unarmoured” means the cable does not include a dedicated armour layer, such as steel wire or steel tape, for mechanical protection. It does not mean the cable has no metallic components: a medium voltage design commonly has a metallic screen around the insulated core or cores. That screen serves electrical functions, including carrying capacitive charging current and providing a path for fault current when designed and connected accordingly.
Typical cable construction
A common design starts with a copper or aluminium conductor, followed by a conductor screen, insulation, and an insulation screen. XLPE is widely used as the insulation material in modern medium voltage cable designs, although the specified material should always be checked against the project requirements. A metallic screen and outer sheath complete the cable construction; some designs may include additional layers or different material options.
The screen design, conductor material, insulation thickness, sheath compound, and core arrangement all affect cable performance and installation requirements. Unarmoured cable depends on the route and installation method to manage external impact risks. We therefore recommend reviewing the complete construction drawing or datasheet rather than relying on the product name alone.
Voltage and core options
Medium voltage ratings are stated using the U0/U format, where the values describe the rated voltage between conductor and earth and between conductors. Common examples include 6/10 kV, 8.7/15 kV, and 12/20 kV, but the correct rating depends on the system voltage, earthing arrangement, and applicable standard. Do not select a cable from nominal voltage alone; confirm the required U0/U and maximum system voltage with the project engineer.
Projects may specify single-core or three-core cable. The choice affects termination planning, route layout, installation practices, and the way conductors are arranged, particularly where magnetic effects or parallel runs need consideration. The cable schedule and installation design should establish the appropriate configuration.
Applications and Installation Matching
We commonly recommend evaluating unarmoured designs for indoor substations, industrial facilities, cable ducts, and other routes where the cable is protected from foreseeable mechanical damage. They may also be considered for suitable tray or tunnel installations when the project’s support, access, and protection measures match the cable design. Suitability cannot be assumed from the application label alone: site conditions and local requirements matter.
Where a cable could be exposed to impact, crushing, excavation, or other mechanical hazards, the design team should assess whether armour, a protective conduit, a covered trench, or another engineered measure is needed. Direct burial should only be considered when the cable construction and installation specification explicitly permit it and the route has been assessed for mechanical and environmental risks. We advise buyers to document the installation method before comparing unarmoured and armoured quotations.
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Selection Framework for B2B Buyers
1. Confirm electrical requirements
Start with the system voltage, required cable rating, conductor material, conductor cross-section, and core count. Confirm the short-circuit duty and the required metallic screen rating with the engineering team, since conductor and screen sizing depend on project conditions. Also identify the applicable product standard and any additional utility or owner specification.
2. Describe the installation environment
Provide the supplier with the route type, installation method, ambient conditions, moisture exposure, chemical exposure, and expected mechanical protection. Include relevant details such as whether the cable will be installed indoors, in a duct, on a tray, or in a trench. These details help determine whether the requested sheath and overall construction are appropriate.
3. Check installation and accessory compatibility
Confirm the cable’s outer diameter, approximate mass, minimum bending radius, pulling limits, and termination requirements from the selected manufacturer’s documentation. These values vary by voltage rating, cross-section, core arrangement, and construction, so we do not recommend applying a generic figure. Check that joints, terminations, glands, and supporting hardware are compatible with the actual cable dimensions and screen design.
4. Compare the specification, not just the price
Compare quotations against the same voltage rating, conductor material, cross-section, insulation, screen construction, sheath, standard, and delivery scope. Ask suppliers to identify any deviations clearly and provide a technical datasheet and construction details for review. A lower initial quotation may not represent an equivalent product if construction, documentation, or included services differ.
Pricing, MOQ, and Lead-Time Considerations
Medium voltage cable pricing is quotation-based because material selection, conductor size, voltage rating, order quantity, construction, and packaging can all affect the offer. Minimum order quantity and production lead time may also vary with the requested specification and current production schedule. We recommend sharing a complete cable schedule and required delivery window so that suppliers can respond against a defined scope.
For a more useful comparison, request pricing by cable item and length, state the delivery destination and packaging preference, and ask which technical documents are included. Confirm whether the quoted lead time begins after technical approval, order confirmation, or another agreed milestone. Treat any indicative price or schedule as subject to final specification and order review.
Supplier Evaluation Checklist
- Can the supplier provide a datasheet and construction details matching the requested specification?
- Are voltage designation, conductor material, core arrangement, screen, and sheath clearly stated?
- Does the offer identify the applicable standards and disclose any deviations?
- Can the supplier clarify available lengths, packaging, minimum order quantity, and estimated lead time?
- Is technical communication available to resolve questions about installation conditions and accessories?
We encourage buyers to evaluate the supplier’s response quality as well as the commercial offer. Clear documentation helps the project team verify that the cable under review matches the intended application. Any certification, inspection, or testing requirement should be stated explicitly and confirmed for the specific order rather than assumed.
Summary and Next Steps
Medium voltage unarmoured cable can be a suitable option when the electrical design is correct and the installation route provides the required mechanical protection. Its construction commonly includes screened insulation and a metallic screen, even though it has no armour layer. The key selection checks are voltage rating, conductor and screen sizing, installation environment, applicable standards, and compatibility with accessories.
To move forward, prepare the cable schedule, confirm the route and protection method, and identify the required documentation and delivery conditions. Zhongdong Cable Co., Ltd. can discuss medium voltage unarmoured cable requirements and provide product information for buyer review. Send us your voltage rating, conductor details, core arrangement, standard, quantity, and destination to request a specification-based quotation.