Medium Voltage Unarmoured Cable: Applications, Selection, and Installation Requirements
Medium voltage unarmoured cable is designed to carry electrical power at medium voltage without a metal armour layer. It is commonly considered for indoor installations, cable trays, and ducts where the route provides adequate mechanical protection. Whether it is suitable for a project depends on the system voltage, installation environment, fault conditions, and applicable electrical codes. We recommend confirming these factors before specifying or ordering cable.
This guide explains where unarmoured cable can be used, how to select its construction, and what to verify during installation. It also provides a practical supplier checklist for buyers sourcing medium voltage (MV) cable. Zhongdong Cable Co., Ltd. can review project requirements and discuss a suitable cable configuration based on the information provided.
Key Takeaways
- Unarmoured MV cable is most appropriate when the installation route offers mechanical protection or the project design provides it separately.
- Selection should account for rated voltage, conductor material and size, insulation, screens, sheath, environment, and installation method.
- Do not assume that an unarmoured construction is suitable for direct burial or exposed routes; confirm the design and local requirements first.
- For an accurate quotation, provide a cable schedule, applicable standard, quantity, delivery destination, and project timeline.
Who This Guide Is For
This guide is intended for electrical contractors, EPC teams, distributors, project engineers, and procurement professionals evaluating MV cable. It is useful when comparing unarmoured and armoured constructions or preparing a technical request for quotation. It is not a substitute for a project-specific cable calculation or approval by a qualified electrical designer. Installation and testing must follow the applicable standards, local regulations, and manufacturer instructions.
What Is Medium Voltage Unarmoured Cable?
Medium voltage unarmoured cable is a power cable with conductor insulation and protective cable layers but without metal wire or tape armour. Typical constructions may include a copper or aluminium conductor, conductor screen, insulation, insulation screen, metallic screen, and an outer sheath. The exact layer arrangement depends on the cable design, voltage class, standard, and project specification.
The metallic screen is not the same as armour. A screen is an electrical component that manages the electric field and provides a path for capacitive or fault current when correctly bonded. Armour, by contrast, is primarily a mechanical protection layer and may also have an electrical role depending on the system design. Buyers should check the cable datasheet rather than infer construction from a product name alone.
Voltage and Material Options
MV cable is specified by rated voltage, commonly shown as U0/U (Um), where the values describe voltage to earth, voltage between conductors, and the highest system voltage. For example, 6/10 kV and 8.7/15 kV are voltage designations used in some cable specifications; the correct choice depends on the network and applicable standard. IEC 60502-2 is one standard used for extruded-insulation power cables in its stated voltage range, but the project documents determine which standard and voltage class apply.
Conductors are generally specified as copper or aluminium, with the material and cross-sectional area selected through electrical and installation calculations. XLPE is a common insulation option for MV cable, while the conductor, insulation, and sheath specifications must be confirmed against the required operating conditions. A 35 mm² conductor, for instance, is only an example size and should not be treated as a recommendation without load, voltage-drop, short-circuit, and installation data.
Applications and Route Suitability
Unarmoured MV cable may be suitable for indoor substations, industrial facilities, power distribution rooms, and installations in ducts or trays where the route is protected from impact and other mechanical hazards. It can also be considered for infrastructure and utility projects when the cable is installed within a designed protective system. The engineering team should assess the full route, including transitions, access points, and areas exposed to construction activity.
Unarmoured cable is not automatically suitable for direct burial, exposed outdoor runs, or locations at risk of crushing, impact, or digging damage. A duct does not eliminate every risk: water ingress, pulling tension, bend radius, and duct capacity still need to be evaluated. Where the route cannot provide sufficient protection, an armoured construction or separate mechanical protection may be required.
Installation Requirements to Confirm
Before installation, verify the approved cable schedule, drum identification, cable condition, pulling plan, route drawings, and compatible accessories. Installation teams should observe the manufacturer’s minimum bend radius and maximum pulling tension; these limits depend on cable diameter and construction, so a universal figure should not be assumed. Keep cable ends sealed during storage and installation to help prevent moisture or contamination from entering the cable.
With competitive price and timely delivery, Zhongdong Cable Co., Ltd. sincerely hope to be your supplier and partner.
After installation, complete the inspections and electrical tests required by the project specification and applicable standards. The test method and acceptance criteria should be agreed with the responsible engineer and cable manufacturer before testing. For XLPE cable, the maximum normal conductor operating temperature is commonly specified as 90°C, but the permitted temperature and any emergency or short-circuit limits must be confirmed for the exact cable design and governing standard.
How to Select the Right Cable
1. Define the Electrical Duty
Start with system voltage, frequency, load current, fault level, protection-clearing time, and earthing arrangement. Have a qualified designer verify conductor sizing, current-carrying capacity, voltage drop, and short-circuit withstand. These values are affected by installation conditions and should not be selected from conductor size alone.
2. Specify the Route and Environment
Document whether the cable will be installed in air, on a tray, in a duct, or underground, and identify ambient temperature, grouping, moisture, chemicals, UV exposure, and mechanical risks. Include route length, pulling access, bends, and any special fire or smoke requirements. This information helps determine whether an unarmoured construction is appropriate and what sheath materials or additional protection may be needed.
3. Confirm Construction and Compliance
State conductor material and size, voltage designation, insulation type, screen requirements, sheath material, number of cores, and required drum length. Identify the applicable standard and any project-specific inspection or documentation requirements. Ask the supplier to confirm the proposed construction against the specification and clearly list any deviations before approval.
4. Check Accessories and Installation Compatibility
MV terminations and joints must match the cable voltage class, conductor, insulation dimensions, screen arrangement, and installation environment. Confirm accessory availability and compatibility early, especially when a project uses a specified accessory brand or design. Coordinate cable and accessory approvals so that procurement decisions do not leave the installation team without compatible components.
Pricing, MOQ, and Lead Time
The price of MV unarmoured cable depends on factors such as conductor material and size, voltage class, insulation and sheath construction, order quantity, drum length, packaging, and destination. Copper and aluminium options can have different material costs, while non-standard requirements may affect production planning. A comparable quotation should include the full construction, standard, quantity, delivery terms, and required documents rather than only a price per metre.
Minimum order quantity and lead time vary by specification, production schedule, and available materials. We avoid giving a general lead-time promise without reviewing the requested design and quantity. For planning, buyers should request a confirmed production and dispatch schedule, clarify whether partial shipments are possible, and include any inspection or approval stages in the project timeline.
Supplier Evaluation Checklist
- Can the supplier provide a datasheet that identifies the full cable construction and rated voltage?
- Can the proposed design be reviewed against the project standard and installation conditions?
- Are routine inspection records and other required quality documents available for the supplied order?
- Can the supplier confirm drum lengths, packaging, marking, delivery terms, and schedule?
- Will the supplier identify deviations and obtain approval before production?
Buyers should evaluate responses against the project specification rather than relying on broad claims about quality or performance. Request documentation that corresponds to the actual offered construction and clarify the scope of any inspection or testing. If a requirement is unclear, resolve it before placing the order to reduce the risk of mismatched cable, accessories, or delivery expectations.
Conclusion and Next Steps
Medium voltage unarmoured cable can be a suitable choice when the electrical design is correct and the installation route provides adequate mechanical protection. It should not be selected on voltage or price alone; the conductor, insulation, screen, sheath, accessories, route conditions, and governing requirements all matter. For exposed or mechanically vulnerable routes, ask the project designer to assess whether armour or separate protection is necessary.
To request a project review or quotation from Zhongdong Cable Co., Ltd., prepare the voltage designation, applicable standard, cable schedule, quantity, installation method, destination, and target delivery date. We can use these details to discuss a suitable construction, documentation needs, and quotation scope. Final selection and installation approval should remain with the responsible project engineer and authority having jurisdiction.