Steel wire armoured cable to BS 5467 is the standard UK power cable for anything running outdoors, underground or through an area where it could be struck. XLPE insulated cores are laid up, bedded, wrapped in a layer of galvanised steel wires and sheathed in black PVC. The XLPE gives a 90 °C conductor rating and the steel armour provides both mechanical protection and a usable protective conductor.
Key applications
- Buried supplies to outbuildings, garages, workshops and garden lighting
- Submains between buildings on a site
- Supplies to external plant, pumps, gates and car park lighting
- Industrial power distribution on tray, ladder and cleats
- Any run where impact, rodents or excavation are a risk
Features and benefits
- Steel armour takes impact and allows direct burial
- Armour can serve as the circuit protective conductor where the adiabatic check allows
- XLPE insulation rated 90 °C, with a 250 °C short-circuit limit
- Black PVC sheath stands up to weather and sunlight better than grey PVC
- Standard core colours to the harmonised scheme, so identification is consistent
Specification notes and limitations
The armour is only a protective conductor if it has been checked against the fault current and disconnection time — on smaller multicore sizes it often is, but it must not be assumed. It has to be glanded correctly at both ends with the right gland type and an earth tag or banjo; a gland that only grips the sheath leaves the armour unearthed and the circuit without a CPC. The 90 °C conductor rating is rarely usable in full because glands, terminals and accessories are commonly rated 70 °C. Buried cables need correct depth, sand or fine bedding, protective tiles or marker tape, and allowance for the reduced rating in the ground. Respect the bending radius: forcing a tight bend opens the armour and can split the bedding. The PVC sheath should not be installed below about 0 °C.
