Construction

construction:

The construction of the conductors shall be as follows:

Nominal Cross-Sectional Area	Nominal Cross-Sectional Area	Solid/Stranded	Flexibility Class
Copper	Aluminium
mm²	mm²
1.5	1.5	Solid	Class 1 (Table-1) of IS:8130*
2.5 to 6	2.5 to 10	Solid/Stranded	Class 1 (Table-1) of IS:8130*
10 and above	16 and above	Stranded	Class 2 (Table-2) of IS:8130*

specification for conductors for insulated electric cables and flexible cord.

Conductors of nominal area less than 16 mm²shall be circular only. Conductor of nominal area 16mm² and above may be circular or shaped.

Cables with reduced neutral conductor shal comply with the main-neutral conductor combination given in the below table:

Nominal Cross-Sectional Area of Main Conductor, mm²	Cross-Section Area of Reduced Neutral Conductor, mm²
25	16
35	16
50	25
70	35
95	50
120	70
150	70
185	95
240	120
300	150
400	185
500	240
630	300

Insulation:

The conductors are insulated with PVC compound by extrusion process.

Core identification:

Cores shall be identified by different colouring of PVC insulation. Following colour scheme shall be adopted:
1Core :Red, black, yellow or blue
2Cores :Red and black
3Cores :Red, yellow and black
4Cores :Red, yellow, blue and black
5Cores :Red, yellow, blue, black and grey
6Cores and above :Two adjacent cores (counting and direction core)in each layer blue and yellow, remaining cores grey.
For reduced neutral conductors, the core shall be black. The insulation conductor is called core.

Inner Sheath:

The cores of multicore cables are laid up and surrounded by PVC covering either by PVC extrusion or by tapping.

Armouring:

Applicatioll-Armourning shall be applied over the insulation in case of singlecore cables and over the inner sheath in case of twin-three- and multi-core cables.
The armour wires/strips shall be applied as closely as practicable.

The direction of lay of the armour shall be left hand. For double wire/strip armoured cables, this requirement shall apply to inner layer of wires/strips. The outer layer shall, except in special cases, be applied in the reverse direction to the inner layer and there shall be a separator of suitable non-hygroscopic material, such as plastic tape, bituminized cotton tape, bituminized hessian tape, rubber tape, proofed tape, etc. between the layers of armour wire/strips.

Type of Armour

Where the calculated diameter below armouring does not exeed 13 mm, the armour shall consist of galvanized round steel wires. Where the calculated diameter below armouring is greater than 13 rnrn, the armour shall consist of either galvanized round steel wires or galvanized steel strips.

Dimensions

The dimensions of galvanized steel wires and strips shall be as specified in Table.

Outer Sheath:

This is provided by means of an extruded PVC over the armour for armoured cables and over inner sheath for unarmoured cables.
PVC usually used to manufacture the type of cable are general purpose PVC suitable to operate at a maximum
conductor temperature of 70' C.

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