IEC 708-2

PRESENTATION

Petroleum jelly filled cables for local distribution telecommunication networks, suitable for drawing into ducts. The armoured cables can be directly burried

REFERENCE STANDARDS

International Electro-technical Commission IEC standard, Publication 708 - 2 and 708 - 1

STRUCTURE

1- Conductors :

Each conductors consist of solid wire of annealed, grade A copper, having a diameter of 0.4 mm, 0.5 mm, 0.6 mm and 0.8 mm.

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2- Insulation of conductors :

Each Conductors of 0.4 mm diameter is insulated with a layer of solid polyethylene. Each conductors of 0.5mm, 0.6 mm and 0.8 mm diameter are insulated with an inner layer of cellular polyethylene and an outer skin of solid polyethylene (Foam-Skin ).
The radial thickness of the insulation is such that the electrical requirements are met.

3- Stranding :

- Quadding :
Four appropriately coloured Insulated conductors are assembled togother to form a quad.
- Unit stranding :
· Five quads are stranded together to form a unit.
· Cables up to 100 pairs are made up by stranding together units of 5 quads (10 pairs).
· Cables of more than 100 pairs are made up by stranding together Main-units of 50, 100 or 150 pairs.
· Main-units and units are identified with an open lapping coloured polyester tape.

4- filling

The cables are fully filled with a high grade, high drop point, petroleum based, jelly compound.

5- wrapping

A wrapping tape is applied over the cable core. It consistes of :
- An outer layer of absorbing paper materiel.
- An inner layer of insulating polyester tape.

6- Screen

Over the wrapped core cable is applied an aluminum tape, coated on one side with polymer. It has a thickness of about 150 m

7- Continuity wire

A tinned copper conductor of 0.5 mm diameter is applied under the screen to ensure its continuity. 86

8- Sheath

The sheath is black low density polyethylene containing 2.5 0.5 % carbon black.

9- Armouring (only for armoured cables)

Over the sheath are applied two steel tapes of 0,2 mm thickness. (A paper tape can be applied just under the armouring).

10- External sheath (only for armoured cables)

The external sheath is black low density polyethylene containing 2,5 0,5% carbon black. The nominal thickness of the sheath is 2,00 mm.