Which lines a distribution network uses
Utility work is dominated by a few heavy constructions bought in large, repeated lots. Medium voltage XLPE cable carries power from primary substations to ring main units and pole or pad transformers. Aluminium XLPE cable is common for low voltage distribution where weight and copper cost matter. Armoured cable protects buried runs, control cable wires the substation, and ADSS fibre on the overhead route carries protection signalling and communications. The table maps the usual sections to lines; the utility's specification decides the construction.
| Circuit or section | Cable line | Typical standard | Typical packing |
|---|---|---|---|
| MV feeders and ring main circuits | MV XLPE cable, copper or aluminium, copper tape screen | IEC 60502-2, 3.6/6 to 18/30 kV | Heavy drums, one run per drum where possible |
| Transformer to LV distribution pillars | Aluminium XLPE cable, multicore | IEC 60502-1; aluminium Class 2 to IEC 60228 | Drums |
| Buried LV and service runs | Armoured cable, STA or SWA; aluminium armoured versions | IEC 60502-1 | Steel-wood or steel drums |
| Substation protection and control wiring | Control and instrumentation cable | Per utility specification | Drums |
| Fibre on the overhead route | ADSS aerial fibre cable | IEEE 1222, IEC 60794-4-20 | Fibre drums with hardware |
| Fibre in substation ducts | Outdoor loose tube fibre cable | Telcordia GR-20 | 2 km / 4 km drums |
Reference constructions from a partner plant catalogue: 8.7/15 kV Cu/XLPE/CTS/PVC 3x95 mm2 with compacted copper, conductor and insulation screens, 4.5 mm XLPE, copper tape screen and a 2.8 mm PVC sheath, about 61 mm overall and about 5,403 kg/km; and 0.6/1 kV Al/XLPE/PVC 4x95 mm2, about 40 mm and about 1,907 kg/km, maximum 0.320 ohm/km. From public datasheets, a 24-core ADSS cable for a 100 m span class is about 10 mm overall and 80-110 kg/km, with a maximum allowable tension of 1,700-2,700 N per datasheet.
Standards and market notes
IEC 60502-2 covers voltage classes from 3.6/6 to 18/30 kV. The partner plant catalogue behind the reference stops at 8.7/15 kV, so 12/20 and 18/30 kV orders are matched to a plant that makes and tests them. Routine tests include a voltage test at 3.5 U0 for 5 minutes and partial discharge to IEC 60885-3, at most 10 pC at 1.73 U0. Metallic screen size is set by the utility from earth fault level and duration. ADSS is specified by span together with weather conditions: the same design that suits a 100 m span may be limited to about 50 m in heavy ice, per maker data. Anti-tracking sheaths are chosen from the line's calculated field strength, a figure the utility's engineer provides. OPGW is a separate category under IEEE 1138; see OPGW vs ADSS.
Drum planning for grid work
MV cable is heavy: at about 5,403 kg/km the 3x95 mm2 reference weighs roughly 2.7 tonnes per 500 m before the drum (calculated from the catalogue weight). Drum length is therefore limited by drum capacity, trailer and crane limits and the pulling plan between joint bays. The drum plan lists each section between joints, the drum assigned to it and the metre marks at both ends. Sealed end caps keep water out of the conductor and screen. Fibre drums carry the OTDR records per fibre. See packaging and drums.
Typical risks on utility projects
- Missing partial discharge records. MV drums without PD results per IEC 60885-3 should not leave the plant.
- Voltage class beyond the plant's range. A plant that lists 8.7/15 kV quoting 18/30 kV without test records.
- Undersized aluminium. Resistance above 0.320 ohm/km on 95 mm2 aluminium Class 2.
- ADSS chosen by span alone. No wind, ice and sag conditions in the brief.
- Water in the cable. Damaged end caps on drums stored outdoors.
Where grid cable comes from and how the desk runs it
Medium and low voltage cable is the core business of Ningjin in Hebei, recognised as a medium and low voltage and new-energy cable cluster, and of Guanlin in Jiangsu, whose cable output was reported at more than 120 billion yuan a year (Xinhua Daily Media, 2025). ADSS comes from the fibre clusters in Wuhan and Qidu. Utility tenders often run as framework lots, so the desk fixes one spec sheet per construction, books copper or aluminium against each call-off, and keeps a drum ledger across deliveries. Copper-linked quotes with an adjustment formula are common on long contracts. Send the route data, voltage class and section lengths through the quote form; MOQ and lead time follow MOQ and lead time, confirmed in writing per order.