MEDIUM VOLTAGE · 12 / 20 kV · IEC 60502-2
Cable XLPE 20 kV
European utility distribution — the most-installed IEC rating outside 11 kV. Three-core or single-core construction, copper or aluminium conductor, manufactured against IEC 60502-2 with project-specific screen sizing, armour and sheath.
§01 — Cable construction
The reference construction, layer by layer.
The 12/20 kV class runs a 5.5 mm XLPE wall with a heavier metallic screen. Above roughly 300 mm², or on longer routes, the build switches to single-core AWA in flat or trefoil formation to avoid magnetic losses in steel armour. Insulation eccentricity and screen coverage are measured on every batch at this level.
| # | Capa | Reference detail |
|---|---|---|
| 01 | Conductor | Cu class 2 stranded (RM). Sector-shaped (SM) for 3-core ≥ 185 mm². |
| 02 | Conductor screen | Extruded semiconducting compound, ≤ 0.5 mm nominal thickness. |
| 03 | Aislamiento XLPE | Extruded XLPE, 5.5 mm nominal across 35–1 000 mm² at 12/20 kV per IEC 60502-2, table 6. |
| 04 | Insulation screen | Extruded semiconducting, strippable or bonded per requirement. |
| 05 | Metallic screen | Cu wire screen per IEC 60502-2; 25 mm² typical for 150–300 mm² conductors, checked adiabatically against your protection settings. |
| 06 | Inner sheath | PVC ST2, extruded bedding. |
| 07 | Armadura | Double steel tape (STA) for direct burial; SWA for higher tensile load; AWA for single-core. |
| 08 | Serving | Anti-corrosion wrap on certain designs (optional). |
| 09 | Outer sheath | PVC ST2 black; PE or LSZH on request. |
§02 — Technical specifications
Electrical parameters — 12 / 20 kV class.
| Conductor (mm² Cu) | Insulation thickness | DC resistance @20 °C (Ω/km) | Indicative current, direct burial 25 °C (A) |
|---|---|---|---|
| 3 × 35 | 5.5 mm | 0.524 | ~170 |
| 3 × 50 | 5.5 mm | 0.387 | ~205 |
| 3 × 70 | 5.5 mm | 0.268 | ~250 |
| 3 × 95 | 5.5 mm | 0.193 | ~300 |
| 3 × 120 | 5.5 mm | 0.153 | ~345 |
| 3 × 150 | 5.5 mm | 0.124 | ~385 |
| 3 × 185 | 5.5 mm | 0.0991 | ~435 |
| 3 × 240 | 5.5 mm | 0.0754 | ~500 |
| 3 × 300 | 5.5 mm | 0.0601 | ~560 |
| 3 × 400 | 5.5 mm | 0.0470 | ~640 |
DC resistance values per IEC 60228. Indicative current: ground 25 °C, soil thermal resistivity 1.5 K·m/W, depth 1.0 m, flat formation — reference only; final ampacity is calculated against your installation conditions. Overall diameter and weight for this voltage class are issued in the project datasheet with the formal offer.
§02B — Worked example · 12 / 20 kV
Short-circuit check for a 20 kV industrial intake.
For a prospective fault of 12.5 kA with 1 s clearing time, the minimum Cu conductor size follows S ≥ I · √t / k with k = 143 A·√s/mm² for Cu/XLPE: S ≥ 12 500 / 143 ≈ 88 mm², so 95 mm² is the smallest safe cross-section. The same logic sizes the steel wire screen against earth-fault duty. Give us your fault level and clearing time and the offer states the verified minimum cross-section.
§03 — Standards
Standards printed on the sheath and on the drum card.
§04 — Applications
Where 20 kV cable from Lulian is in service.
20 kV urban distribution
Three-core CU/XLPE/CWS/STA/PVC for city medium-voltage rings and substation feeders.
Urban and suburban MV distribution →20 kV industrial intake
Primary supply to factories with own 20/0.4 kV transformer stations.
Industrial intake substations →Solar plant collection
20 kV collection feeders between string inverters and the plant substation in European PV parks.
Solar plant collection systems →Not sure which voltage class your network needs? See all cable applications and sector solutions, or send the system voltage and the earthing method — we confirm the class and the construction in the offer.
§05 — Quality testing
What we test on every drum.
Routine tests run on every drum; sample tests on each batch; type tests on new constructions witnessed by CNAS-accredited third-party labs.
- Conductor DC resistance at 20 °C (routine)
- AC voltage withstand AC 42 kV / 5 min (routine)
- Partial discharge ≤ 10 pC at 20.8 kV (1.73 U₀) (sample)
- Insulation thickness & eccentricity (sample)
- Metallic screen cross-section (routine)
- Armour coverage & bedding integrity (routine)
- Sheath thickness + spark test (routine)
- Bending test + voltage after bending (type)
- Impulse voltage 125 kV (type)
§06 — Packaging & delivery
Drums sized for the cable, not for the workshop.
Single-core 20 kV lengths ship in trefoil-bundled formation with spacers, so the core arrangement survives transport without re-forming on site. Wooden drums with fumigation marks for export; steel-plywood drums for heavy cross-sections. Cable ends sealed with heat-shrink caps; shipping marks per the buyer’s format.
Standard drum lengths: 500 / 1000 / 1500 / 2000 m. Lead time: 25–35 working days for stocked constructions; 40–55 working days for project-specific builds.
§07 — FAQ
Common questions on 20 kV cable procurement.
What is the U₀/U rating of 20 kV XLPE cable?
12 / 20 kV, Uₘ = 24 kV — the IEC class for 20 kV rural and industrial networks. For 22 kV BS-designated systems we supply the 12.7/22 kV variant of the same construction.
What conductor cross-sections are available?
Three-core: 25–400 mm². Single-core: 25–630 mm². Copper or aluminium, class 2 stranded; sector-shaped conductors for large 3-core sizes.
Can the cable be direct-buried?
Yes. The armoured construction (STA) with PVC ST2 outer sheath is rated for direct burial. SWA is recommended where tensile load or rodent risk is high.
What is the partial discharge limit?
≤ 10 pC measured at 20.8 kV (1.73 U₀) per IEC 60502-2. PD is measured on every drum and documented on the routine test report.
What routine and type tests are performed?
Routine on every drum: conductor DC resistance, AC voltage withstand AC 42 kV / 5 min, sheath spark test. Sample: PD, insulation thickness, screen check. Type: bending + voltage, load cycle, impulse voltage 125 kV.
Can the cable be supplied with LSZH sheath?
Yes, for tunnel, metro, data centre and indoor substation use. Verified against IEC 61034 (smoke density) and IEC 60754 (acid gas).
Single-core or three-core for a 20 kV industrial intake?
Three-core STA is the default for direct-buried intakes up to around 300 mm². Above that, or where route lengths and pulling forces grow, single-core AWA in flat formation with one-end bonding is the cleaner engineering answer — we state the bonding arrangement and screen cross-section in the offer.
Envíe el programa de cables. Confirmamos la construcción en 24 horas.
Share voltage class, conductor material & size, core count, armour, sheath, installation method, total length and drum preference.
RFQ por correo → sales@luliancable.comAbrir formulario de RFQ
§08 — Related
Other voltage classes & adjacent products.
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