Armouring for copper cables

Metallic armour are used when cables have to be installed direct buried, or if mechanical protection is required.
Following points must be considered:


    Required tensile load
    Expected pressure on cable during service
    Protection against rodent
    Protection against accidental damage
    Minimum required bending radius


SWA: single layer of galvanized steel wires, with diameters according to relevant standards, coverage min. 90%. This armour assures a very good mechanical protection and tensile strength. An additional counterspiral tape increases solidity, if required.


GSWB: galvanized steel wire braid, diameter of wire: 0.20 - 0.25 - 0.30 - 0.40 mm, with coverage of >80%. It assures a good mechanical resistance, allowing a lower bending radius compared to other armour. It is preferable when there is movement or vibration.
For special application is possible to use stainless steel, tinned copper or special alloy wires



GSTA: galvanized steel tape armour, composed by two tapes with overlapped edge; thickness of each tape: 0.20 – 0.30 – 0.40 mm, according to cable diameter. It grants a coverage > 100%. Very good crush resistance, but fair tensile strength.
Brass tape of minimum thickness 0.075 mm can be used for special applications.



GSFA: galvanized steel flat armour. It is composed by flat wire of thickness 0.6 mm or 0.8 mm, it is similar to SWA, but with higher mechanical protection.



source from : cavicel