Pair twisted telephone cables with three-layer

1 Conducting cores - single-wire from copper soft wire. 2 Insulation - film-porous-film (three-layer, consisting of solid, porous and solid layers of polyethylene). 3 Pairs - twisted from insulated conductors of different colours.

Pairs are twisted into five or ten-pair elementary bundles. 4 Core - twisted from elementary bundles of different colours. 5 Belt insulation - polyethylene terephthalate film overlapped, polypropylene uniaxially oriented film overlapped.

6 Shield: aluminium-polyethylene tape laid lengthwise. Tinned copper wire is laid longitudinally under the screen. 7 Sheath: polyethylene.

8 Protective cover - of two tapes of crepe paper, overlapped, a layer of bitumen, two steel galvanised tapes, overlapped with a gap.