Medium Voltage XLPE Cable Selection Guide: Voltage Rating, Armour and IEC 60502-2

A medium voltage cable inquiry needs more than conductor size and total length. Voltage class, core configuration, conductor material, screen design, armour, sheath, installation route, testing and documentation must be reviewed as one cable design. The following sequence helps EPC and procurement teams prepare a clear RFQ for medium voltage XLPE power cables from 3.6/6 kV to 35 kV.

1. Identify the system voltage and cable voltage class

Start with the system nominal voltage, maximum system voltage where specified, earthing arrangement and the cable voltage designation required by the project. Common project classes can include 3.6/6 kV, 6/10 kV, 8.7/15 kV, 12/20 kV, 18/30 kV, 21/35 kV and 26/35 kV, but these designations are not automatically interchangeable. The cable rating must follow the confirmed system and project specification.

International RFQs may describe a project simply as an “11 kV cable” or “33 kV cable” requirement. Those system-voltage labels alone do not confirm the cable's U₀/U(Um) designation, required insulation level or test scope. Please provide the approved project cable schedule or specification, including the requested voltage designation and earthing assumptions where stated, before an equivalent cable construction is reviewed.

IEC 60502-2 is commonly referenced for medium-voltage power cable project specifications within its applicable scope. IEC 60502-2-based project requirements can be reviewed against the confirmed cable design, testing scope and documentation requirements. This is a specification-review statement, not a certification claim.

2. Confirm single-core or three-core construction

State whether the circuit requires single-core or three-core cable. The decision affects the physical construction, installation arrangement, armour review, drum planning and accessories. Provide the cable schedule or single-line diagram where available. If the BOQ and technical specification show different core configurations, resolve the conflict before the quotation is finalized.

3. Select copper or aluminium conductor

Copper and aluminium conductor options can be reviewed, depending on the project requirement. Confirm the required material explicitly and consider the project’s termination design, size, installation constraints and commercial evaluation. A quotation should not substitute one conductor material for the other without an agreed technical and commercial review.

4. Confirm conductor cross-section

Provide the specified nominal cross-section for each circuit. Cable sizing is normally determined by the project designer using load, voltage drop, short-circuit, installation and derating criteria. Huanyu Cable can review the requested construction for quotation, but unconfirmed project calculations should not be replaced by a generic size recommendation.

5. Define conductor, insulation and metallic screens

A screened MV XLPE cable typically includes a conductor screen, XLPE insulation, an insulation screen and a metallic screen. Confirm the metallic screen form and required area, such as a specified copper tape or other project-defined arrangement. Screen design influences the cable construction and must match the system, fault-current study, accessories and specification. Do not submit only “XLPE cable” if the screen details are stated elsewhere in the project documents.

6. Review unarmoured, STA or SWA construction

Unarmoured cable may be reviewed for protected routes. Steel tape armour, or STA, is typically considered for applicable multicore designs requiring radial mechanical protection. Steel wire armour, or SWA, may be reviewed where the route and specification require wire armour or defined mechanical and tensile protection. The choice depends on installation route, pulling conditions, core configuration and circuit design; the three options should not be treated as automatic substitutes.

For a focused comparison of the two armour approaches, see the STA vs SWA Armoured Cable guide. Huanyu’s Low Voltage Armoured Power Cables page is relevant only when the project package also includes LV armoured circuits.

7. Confirm PVC, PE or project-specific sheath requirements

Specify the outer sheath material, colour, marking and any route-specific environmental requirement. PVC and PE sheath options are reviewed according to the cable design and project conditions. If the route requires low-smoke, flame-retardant or fire-resistant performance, define each requirement separately rather than using “fire-safe” as a substitute for a test scope. The LSZH & Fire-safe Cables page explains these distinctions and the information required for review.

8. Describe the installation route

Identify ducts, trenches, tunnels, trays, direct-burial sections, substation entries, vertical runs and changes along the route. Include planned pulling conditions and relevant environmental information. Route details support the review of armour, sheath, cable dimensions, drum length and handling requirements. A single route label rarely provides enough information for final construction confirmation.

9. Confirm standards, testing and document scope

List the applicable standard and any project-specific additions. State the required routine, sample or type-test evidence, inspection arrangement, test reports, drawings, data sheets, packing records and marking requirements. Third-party inspection or testing can be discussed when specified, but the organization, witness scope, acceptance criteria, timing and cost responsibility should be confirmed before quotation.

Huanyu Cable reviews IEC 60502-2-based, applicable GB/T or project-specific requirements against the confirmed cable design. Final testing and document commitments should appear in the quotation or agreed technical file; a general reference to a standard should not be read as an unverified product certification.

BOQ and RFQ checklist

• System voltage, cable voltage designation and earthing information where specified
• Single-core or three-core construction
• Copper or aluminium conductor and nominal cross-section
• Conductor screen, insulation screen and metallic screen design
• Unarmoured, STA or SWA requirement
• PVC, PE or project-specific sheath and fire-performance requirements
• Installation route and pulling conditions
• Applicable standard, testing, inspection and document scope
• Cable quantity, drum length, destination and required schedule