Understanding the build-up of a covered conductor helps buyers write better tender clauses and helps installers handle it correctly. The chart below follows the construction described on the APAR product page, from the inside out.
Construction layers
| Layer | Name | Material | Purpose |
|---|---|---|---|
| 1 | Stranded conductor | Longitudinally water-tight ACSR, AAAC, AL-7 or AL, or a high-temperature conductor | Carries the current and the mechanical load. The water-tight build stops moisture travelling along the strands. |
| 2 | Semi-conducting screen | Water-swellable semi-conducting tape plus an extruded semi-conducting compound | Smooths the electric field at the conductor surface and adds a further barrier to moisture. |
| 3 | Inner insulation | Carbon-free XLPE | Provides the main insulating layer. |
| 4 | Outer insulation | UV-protected, anti-tracking black covering | Resists sunlight, surface tracking and weathering. The screen and both insulation layers are co-extruded and bonded together. |
Ratings and sizes
| Item | Detail |
|---|---|
| Voltage classes | 11, 22, 33, 66, 110 and 132 kV |
| Conductor size | 100 to 400 sq mm |
| Conductor types | AAAC, ACSR, ACSS and AL59 ACS |
| Design standards | SS-EN 50397-1, BS EN 50182, IS 398 Part 2 and Part 4, IEC 61089 |
Why the build matters on site
The covering is bonded to the screen, so damage to the outer layer should be reported and repaired with the correct method. Accessories are matched to the covered construction and comply with EN 50397-2. Using bare-line fittings can damage the covering.
The covering does not make the line safe to touch, and the line must be treated as live at all times. See the MVCC product page for the range, the selection guide for choosing a class and the accessories guide for fittings.