2core telephone cable Manufacturer Sheath Material 2 core telephone cable with Aramid Strength member

1. Conductors

—Material

The copper properties must be in conformity with CEI 60028 norms.

—Diameter / Caliber

The nominal conductor diameter must be 0,50 mm, with a tolerance of ± 1,5%. (for 1 x 2 x 0,5mm)

The nominal conductor diameter must be 0,80 mm, with a tolerance of ± 1,5%. (for 1 x 2 x 0,8mm)

—Material

The conductor isolation must be in solid polyethylene of medium density, (from 0,925 g/cm3 up to 0,940 g/cm3) type 03 in accordance with BS 6234, with anti-oxidants properties or equivalent material which guarantee the electrical and transmission characteristics defined.

—Coloring

The isolation colors are White and blue.

2. Strength member

The strength member must conferee the adequate mechanical resistance to the traction effort indicated in section 4.

The materials to be used as strength member must be flexible, lights, with low expansion coefficient, high elasticity module and dielectric characterization in order not change the electrical and transmission characteristics in all range of work frequency (up to 16MHz).

3. Sheath Material

The sheath material must be in medium density polyethylene, holes free, emendation, porosities, fissures and other defects, with adequate treatment to support the atmosphere agents an in particular the UV radiations. 

The sheath material must be black color with 2% up to 3% of the black carbon content uniformly distributed.

4. Dimensions

The minimum thickness of the sheath must be 0,5 mm.

5.Cable construction

—Wires

The cable is formed by two isolated conductors (identified by colors as referred) and twisted, with an adequate step-twisting to obtain the electrical and transmission characteristics required that could not exceed 100m.

 —Wrapping

To avoid the contact between the conductor’s isolation and the sheath, the pair is wrapped up by a polyester tape, polypropylene or equivalent material, helicoidally or longitudinally applied, with an overlap minimum of 20% of its width.  

—Cable nucleus

The wires pair together with the strength member and the ripcord are arranged in parallel, without being twisted. 

The conductor elongation rupture must be inferior than 15% measured at 20ºC

—Outer diameter

The maximum outer diameter of the delivery cable, determined in accordance with the section 2.2.3 of CEI 60189-1, must be 5,5mm.

In the points that the cable is not perfectly cylindrical, the average between the maximum dimension and the minimum dimension must be within 5,0 mm and 5,5 mm, but the maximum dimension could not be superior than 5,7 mm.

  
Electrical characteristics 

1. Electric resistance and Unbalance resistance

Wire electrical resistance (at 20ºC) ≤ 95 ohm/km (for 1 x 2 x 0,5mm) 

Wire electrical resistance (at 20ºC) ≤ 37 ohm/km (for 1 x 2 x 0,8mm)

Unbalanced resistance between conductors from the same pair ≤ 2,0%

2. Insulation resistance

Insulation resistance (at 20ºC) ≥ 10 000 Mohm.Km

3. Mutual capacitance

Mutual capacitance (at 1 KHz) < 55 nF/Km

Spark test

The isolated conductors must support in a continuous way to the voltage test, the at least 5 KV dc or 3 KV ac, in accordance with the method defined in BS 5099 or equivalent.